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iii Climate and Land Surface Changes in Hydrology Edited by Eva Boegh, Eleanor Blyth, David M. Hannah, Hege Hisdal, Harald Kunstmann, Bob Su & Koray K. Yilmaz IAHS Publ. 359 (2013) ISBN 978-1-907161-37-7, 470 + x pp. Price £95.00 Focuses on field-based and modelling studies addressing the sensitivity of hydrological and hydrometeorological fluxes of the coupled land– atmosphere system to climate and land-use change at local, regional and global scales. The volume includes significant model-based studies evaluating methodologies and impacts of using climate and weather prediction data including downscaling and uncertainty analyses. Hydrological sensitivity and impacts due to spatial and temporal land-use and land-cover variability are reported for a wide variety of environmental settings. Observational and model-based investigations assess the significance of land cover and hydrological dynamics for the development of land surface heat fluxes and regional climate. Several empirical hydroclimatological studies, some from remote and data-scarce regions, and others using long-term multi-variable time series data or Earth Observations to evaluate temporal and spatial variability in precipitation, evapotranspiration and hydrological predictions, are included. iv Preface Climate and land-use change complicate current and future water management challenges through their complex and shifting interactions that alter space–time patterns of hydrological variability and induce uncertainty in the decision making processes. Limitations of traditional hydrological analyses and model approaches based on concepts of stationarity of hydrological events need to be understood and alternative methods explored to deal with environmental change. This volume includes a selection of papers which were presented at the International Association of Hydrological Sciences (IAHS) symposium on Climate and Land Surface Changes in Hydrology, conducted in Gothenburg, Sweden, as part of the IAHS-IAPSOIASPEI Joint Assembly, 22–26 July 2013. The focus of the symposium was on field-based and modelling studies addressing the sensitivity of hydrological and hydrometeorological fluxes of the coupled land–atmosphere system to climate and land-use change at local, regional and global scales. The symposium was jointly sponsored by the IAHS international commissions on Coupled Land–Atmosphere Systems (ICCLAS), Remote Sensing (ICRS) and Surface Water (ICSW), and the Global Land/Atmosphere System Study (GLASS) of the Global Energy and Water Exchanges Project (GEWEX). Important objectives of the symposium were to address the effects of past, current and future climate and land-use changes on hydrological processes, including climate–hydrology feedback processes, and to evaluate the impacts of such changes on water resources and flood and drought risks. Methodological approaches and results related to the representation of the coupled land surface–hydrological–climate system were of particular concern. This volume comprises a large number of significant model-based studies evaluating methodologies and impacts from using climate and weather prediction data including, for example, downscaling and uncertainty analyses. Furthermore, hydrological sensitivity and impacts due to spatial and temporal land use and land cover variability are reported for a wide variety of environmental settings. Observational and model-based investigations are presented to assess the significance of land cover and hydrological dynamics for the development of land surface heat fluxes and regional climate. A number of empirical hydroclimatological studies are captured herein, some from remote and data-scarce regions, and others using long-term multi-variable time series data or Earth Observations to evaluate temporal and spatial variability in precipitation, evapotranspiration and hydrological predictions. The book has been organised in five thematic sections: Climate Change and Extreme Events Climate Change and Water Resources Climate and Spatial Hydrological Processes Land–Atmosphere Research in Hydrology Land Cover Change and Hydrological Processes We wish to thank all authors for providing papers according to a tight schedule and for responding in a timely fashion to fulfil editors’ and referees’ requests and recommendations. In addition, we wish to acknowledge the great job of many authors in providing thorough reviews of other papers submitted for this publication. Finally, we are very grateful to Cate Gardner at IAHS Press for her professional and efficient work to organise the set-up and publication of this book. v It is our hope that this edited volume provides a state-of-the-art overview of research challenges, methodological approaches and scientific progress that will be useful for sharing insights and that will stimulate discussions related to the understanding and prediction of climate and land-use change impacts on hydrological processes, water resources, floods and drought risks. EDITORS Eva Boegh Department of Environmental, Social and Spatial Change (ENSPAC) Roskilde University, Denmark Eleanor Blyth Centre for Ecology & Hydrology, UK David M. Hannah School of Geography, Earth and Environmental Sciences University of Birmingham, UK Hege Hisdal Norwegian Water Resources and Energy Directorate, Norway Harald Kunstmann Institute of Meteorology and Climate Research Karlsruhe Institute of Technology (KIT), Germany Bob Su Department of Water Resources, ITC University of Twente, the Netherlands Koray K. Yilmaz Department of Geological Engineering Middle East Technical University, Turkey 6 Contents Preface by Eva Boegh, Eleanor Blyth, David M. Hannah, Hege Hisdal, Harald Kunstmann, Bob Su & Koray K. Yilmaz 1 iii Climate Change and Extreme Events Seamless forecasting of extreme events on a global scale Florian Pappenberger, Fredrik Wetterhall, Emanuel Dutra, Francesca Di Giuseppe, Konrad Bogner, Lorenzo Alfieri & Hannah L. Cloke (Keynote) 3 Accounting for climate change and uncertainty: experience from strategic adaptation projects in Sweden Sten Bergström & Johan Andréasson 11 Hydrological flood design in Sweden – Climate change and inherent uncertainties Johan Andréasson, Sten Bergström, Jonas German & Kristoffer Hallberg 17 Impacts of climate and land-use changes on floods in an urban catchment in southeast Queensland, Australia Yi-Ru Chen & Bofu Yu 23 Synchronous linked changes in rainfall, floods and river channel changes in southeastern Australia since European settlement Wayne D. Erskine 30 Effect of climate change on flood events as a major driver of nutrient transport in western Japan Yuta Shimizu & Shin-ichi Onodera 38 2 Climate Change and Water Resources Global climate change impacts on freshwater availability – an overview of recent assessments Dieter Gerten (Keynote) 47 Post-processing of climate projections for hydrological impact studies: how well is the reference state preserved? J. Dahnè, C. Donnelly & J. Olsson 53 Water supply capacity of a meso-scale Mediterranean catchment under climatic and anthropogenic changes Lila Collet, Denis Ruelland, Valerie Borrell-Estupina, Alain Dezetter & Eric Servat 60 Evaluation and comparison of two downscaling methods for daily precipitation in hydrological impact studies J. Carreau, A. Dezetter, H. Aboubacar & D. Ruelland 67 Evaluation of two bias-corrected regional climate models for water budget simulations in a Mediterranean basin Zoubeida Bargaoui, Asma Foughali, Yves Tramblay & Ahmed Houcine 73 Automated statistical downscaling in several river basins of the Eastern Monsoon region, China Zongxue Xu, Pin Liu & Wenfeng Liu 80 Dramatic localised climate change effects on water resources David Munday, Ian Cordery & Dale Rubinstein 86 Assessing the impact of land use/land cover and climate changes on water stress in the derived savanna Amidu Ayeni, Evison Kapangaziwiri, Alabi Soneye, Sajith Vezhapparambu & Jimmy Adegoke 92 7 Impacts des changements globaux sur les ressources en eau dans la zone sahélienne en Afrique de l’Ouest / Impacts of global changes on water resources in the Sahel of West Africa Tazen Fowe, Jean-Emmanuel Paturel, Harouna Karambiri, Hamma Yacouba, Pierre Diello & Gil Mahé 99 The impact of climate change on river flow in arid and semi-arid rivers in Algeria Ayoub Zeroual, Mohamed Meddi & Safia Bensaad 105 Impacts of climate change on hydrology in the Srepok watershed, Vietnam Dao Nguyen Khoi 111 Dynamic modelling for assessing the impact of climate change on the hydrological regime of Chenab basin, NW Himalayas A.S. Jasrotia, Deepika Baru & Farha Nishat 118 Drought risks and impact on water resources in part of northern Nigeria Olusegun Adeaga 124 3 Climate and Spatial Hydrological Processes Embedding complex hydrology in the climate system – towards fully coupled climate– hydrology models Michael Butts, Søren H. Rasmussen, Marc Ridler, Morten A.D. Larsen, Martin Drews, Sara Lerer, Jesper Overgaard, Jesper Grooss, Dan Rosbjerg, Jens H. Christensen & Jens C. Refsgaard (Keynote) 133 Impact of groundwater dynamics and soil-type on modelling coupled water exchange processes between land and atmosphere Benjamin Fersch, Sven Wagner, Thomas Rummler, David Gochis & Harald Kunstmann 140 Investigating the importance of groundwater for near surface flux and state simulation through a multi-constraint analysis of a complex surface–subsurface–atmosphere model Simon Stisen, Torben Obel Sonnenborg & Jens Christian Refsgaard 146 Hydrometeorological modelling for Poyang Lake region, China S. Wagner, B. Fersch, H. Kunstmann, F. Yuan, C. Yang & Z. Yu 152 A new curve for representing the spatial distribution of rainfall Dweependra N. Kalita 158 Regional calibration against multiple data sources to predict streamflow J. Vaze, Y. Zhang, F.H.S. Chiew, B. Wang & J. Teng 165 Distributed hydrological modelling for estimation of hydrological dynamics in a karst region Zhicai Zhang, Xi Chen, Yanfang Zhang & Runrun Zhang 171 Space–time variability of rainfall and hydrological trends in the Alto São Francisco River basin Richarde Marques da Silva, Celso Augusto Guimarães Santos, Mônica Larissa Aires Macêdo, Leonardo Pereira E. Silva & Paula Karenina De Macedo Machado Freire 177 Hydro-climatic variability in two Moroccan basins: comparative analysis of temperature, rainfall and runoff regimes Kenza Khomsi, Gil Mahe, Mohamed Sinan & Maria Snoussi 183 Evolution et régionalisation des précipitations au nord de l’Algérie (1936–2009) / Evolution and regionalization of precipitation in northern Algeria (1936–2009) Sabrina Taibi, Mohamed Meddi, Doudja Souag & Gil Mahe 191 Simplified methodology for floodplain inundation modelling using LiDAR DEM J. Teng, J. Vaze, & D. Dutta 198 Building flood inundation modelling capability in river system models for water resources planning and accounting D. Dutta, J. Teng, J. Vaze, J. Hughes, J. Lerat & S. Marvanek 205 8 4 Land–Atmosphere Research in Hydrology GEWEX Land–Atmosphere Research: An Outlook Peter J. van Oevelen, Joseph A. Santanello, Martin Best, Aaron Boone & Bart J.J.M. Van Den Hurk (Keynote) 215 A combined water and energy flux observation and modelling study at the TERENOpreAlpine observatory H. Kunstmann, L. Hingerl, M. Mauder, S. Wagner & R. Rigon 221 Field and simulation experiments for investigating regional land–atmosphere interactions in West Africa: experimental set-up and first results Jan Bliefernicht, Harald Kunstmann, Luitpold Hingerl, Thomas Rummler, Sabine Andresen, Matthias Mauder, Rainer Steinbrecher, René Frieß, David Gochis, Ursula Gessner, Emmanuel Quensah, Ayoola Awotuse, Frank Neidl, Carsten Jahn & Boubacar Barry 226 Updated vegetation information in high resolution WRF simulations Joakim Refslund, Ebba Dellwik, Andrea N. Hahmann & Eva Boegh 233 The heat flux from the land surface during the pre-monsoon season in the inland region of Thailand Masashi Kiguchi, Shin Miyazaki, Wonsik Kim, Shinjiro Kanae, Taikan Oki, Jun Matsumoto & Takehiko Satomura 239 Effects of soil moisture on a summertime convective rainfall over a mountainous area and its contiguous plain in central Japan Kazuyoshi Souma, Kenji Tanaka, Tadashi Suetsugi, Kengo Sunada, Eiichi Nakakita, Kaoru Takara & Satoru Oishi 246 Observed variations in the Indian monsoon hydroclimate during recent decades M.V.S. Rama Rao, J. Sanjay & R. Krishnan 253 Investigation of urban-induced rainfall in Porto Alegre, Brazil, using TRMM satellite rainfall estimation Cesar Fensterseifer, Daniel Allasia, Jean Favaretto, Raviel Basso, Rutinéia Tassi & Andre L. L. Silveira 260 Modelling and analysis of the impact of urban irrigation on land surface fluxes in the Los Angeles metropolitan area Pouya Vahmani & Terri S. Hogue 266 Evapotranspiration and heat fluxes over a small forest – a study using modelling and measurements Andrey Sogachev, Ebba Dellwik & Eva Boegh 272 Soil and canopy energy balances in a maize field with subsurface drip irrigation Hanieh Kosari, Hossein Dehghanisanij, Farhad Mirzaei & Abdol-Majid Liaghat 278 Assessing climate change induced modification of Penman potential evaporation in the middle reaches of Huai River basin, China ShuLei Zhang, HaiShen Lü, ManHung Le, Wenjun Chou & Yonghua Zhu 283 Drought frequency analysis in China using a 55-year dataset of reconstructed soil moisture Z.Y. Wu, X.Y. Li & G.H. Lu 289 Potential evapotranspiration, SPI, SPEI and surface humidity change over China during 1961–2011 Wen Wang, Rengui Xu & Xi Chen 295 Modification of the standardized precipitation evapotranspiration index for drought evaluation Mingwei Ma, Liliang Ren, He Ma, Shanhu Jiang, Fei Yuan, Yi Liu & Xiaoli Yang 302 9 5 Land Cover Change and Hydrological Processes An approach for transient consideration of forest change in hydrological impact studies Paul Schattan, Massimiliano Zappa, Heike Lischke, Luzi Bernhard, Esther Thürig & Bernd Diekkrüger 311 An approach of coupling topographic indices to dynamic ecosystem modelling Jing Tang & Petter Pilesjö 320 Deforestation impacts on discharge of the Ji-Paraná River – Brazilian Amazon Débora Missio Bayer & Walter Collischonn 327 Climate changes and their major impacts on environmental conditions of a freshwater Brazilian wetland Rutineia Tassi, Juan Martin Bravo, Adolfo Villanueva, David da Motta Marques, Daniel Allasia & Lucas Tassinari 333 Catchment fragmentation and hydro-ecological modification of a raised bog wetland S. Regan & P. Johnston 340 Investigating discharge and rainfall variability in an Amazonian watershed: Do any trends exist? Alphonce C. Guzha, Rodolfo Nobrega, Celso A. G. Santos & Gerhard Gerold 346 Decisions on land conservation practices in a semi-arid region considering hydrological and social drivers Hugo M. Alcântara, John E. B. L. Cunha, Carlos O. Galvão & Itamara M. L. M. Taveira 352 Hydrological non-stationarity in southeastern Australia Nicholas J. Potter, Lu Zhang, Cuan Petheram & Francis H. S. Chiew 358 Investigating the impact of conceptual model uncertainty and diverging climate change scenarios on groundwater nitrate concentration predictions Gernot Klammler, Hans Kupfersberger & Gerhard Rock 364 Subsurface storage in different land use catchments evaluated by deuterium excess Keishi Kudo, Takuto Nagamatsu, Jun Shimada, Naoki Kabeya & Nobuhiro Tanaka 371 Hydrological responses to combined land-use and climate change in three diverse South African catchments Michele L. Warburton, Roland E. Schulze & Graham P. W. Jewitt 377 Assessing hydrological impact of land-use measures on peak discharge and total runoff Zahra Kalantari & Mona Sassner 385 Modelling runoff response to land-use change using an integrated approach in Xiangjiang River basin, China Hongliang Xu, Chong-Yu Xu, Bin Zhou & V. P. Singh 390 Hydrological response to land-use changes in a semi-arid region in China Xiaoli Yang, Yi Liu, Liliang Ren & Shanhu Jiang 397 Télédétection et analyse statistique de la dynamique de la végétation dans un contexte de variabilité climatique sur le bassin versant du Bouregreg (Maroc) / Remote sensing and statistical analysis of the dynamics of vegetation in a climate variability context on the Bouregreg watershed (Morocco) Zamblé Armand Tra Bi, Zueli Koli Bi, Télesphore Yao Brou, Gil Mahe & Anas Emran 403 Assessing the effect of vegetation change on actual evapotranspiration through a hydrological model Yi Liu, LiLiang Ren, XiaoLi Yang, Shan HuJiang & Ming WeiMa 411 Vegetation change and its relationship with precipitation on the southern Tibetan Plateau Zongxue Xu, Wenfegn Liu, Fapeng Li & Pin Liu 418 Impacts of climate and land surface changes on urban catchment hydrology Ranjan Sarukkalige 425 Key word index 430 10 ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 3-10. Seamless forecasting of extreme events on a global scale FLORIAN PAPPENBERGER1, FREDRIK WETTERHALL1, EMANUEL DUTRA1, FRANCESCA DI GIUSEPPE1, KONRAD BOGNER1, LORENZO ALFIERI1 & HANNAH L. CLOKE2,3 1 European Centre for Medium-Range Weather Forecasts, Reading, UK [email protected] 2 Department of Geography and Environmental Science, University of Reading, Reading, UK 3 Department of Meteorology, University of Reading, Reading, UK Abstract Early warning systems of extreme events, such as floods, droughts, strong winds and wild fires as well as vector-borne diseases, at the global scale, are essential due to the combined threat of increased population settlement in vulnerable areas and potential increase in the intensity of extreme weather due to climate change. The European Centre for Medium-Range Weather Forecasts (ECMWF) has in the last year developed prototype early warning systems for floods, droughts, extreme winds, wild forest fires and malaria transmission. This paper assesses the performance of these systems. By providing a comprehensive skill assessment both on a global level and in selected regions, we aim to assess their suitability for eventual integration into decisionsupport frameworks. Key words floods; droughts; fire; malaria; forecasting; ensemble; ECMWF ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) . 11-16 Accounting for climate change and uncertainty: experience from strategic adaptation projects in Sweden STEN BERGSTRÖM & JOHAN ANDRÉASSON Swedish Meteorological and Hydrological Institute, SE-601 76 Norrköping, Sweden [email protected] Abstract In Sweden, adaptation to climate change has been addressed in connection with some strategic projects of national significance. Hydrological upgrading of Swedish dam safety assessments has been in the forefront. This has been followed by studies of risks in the expanding metropolitan areas of Stockholm and Gothenburg, where assumptions about hydrological changes have been combined with considerations about future changes in sea level. The two big lakes, Mälaren and Vänern, and the River Göta älv have also been a focus. A key subject has been how to cope with the inevitable uncertainty, as illustrated by the range of results based on the set of regional climate scenarios available. The way forward has been close co-operation with stakeholders. In the case of dam safety, this was carried out in a joint committee including industry, responsible agencies and researchers. The dialogue within this committee may serve as a model for other sectors. Key words climate change; dam safety; areal planning; user dialogue; uncertainty ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 17-22. Hydrological flood design in Sweden – Climate change and inherent uncertainties JOHAN ANDRÉASSON, STEN BERGSTRÖM, JONAS GERMAN & KRISTOFFER HALLBERG 11 Swedish Meteorological and Hydrological Institute, SE-601 76 Norrköping, Sweden [email protected] Abstract A study on the inherent uncertainties in the Swedish guidelines for hydrological flood design, generated by method-specific conditions as compared to different climate signals, has been carried out for the Swedish hydropower industry. The range of method-specific uncertainties covers a variety of conditions. Climate change was considered by use of an ensemble of 16 regional climate scenarios as input to the hydrological runoff model. The results imply that the uncertainty that is caused by differences in the climate change signal is larger than the inherent uncertainties of the hydrological modelling process. The main conclusion is therefore that it really is important to consider climate change in future determinations of design floods for dams. Another conclusion is that there is a need for re-assessments of early design calculations due to advances in hydrological models and calibration schemes. Key words climate change; dam safety; flood design; hydrological modelling; uncertainties ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 23-29. Impacts of climate and land-use changes on floods in an urban catchment in southeast Queensland, Australia YI-RU CHEN & BOFU YU Griffith School of Engineering, Griffith University, Southport, Queensland 4222, Australia [email protected] Abstract Over the coming decades, the projected land-use change, when coupled with climate change, could potentially lead to an increased risk of flooding in urban catchments. This research aims to examine impacts of climate and land-use changes on floods in southeast Queensland, Australia. A rainfall–runoff routing model, RORB, was first calibrated and validated using observed flood hydrographs for an urbanised catchment, the Bulimba Creek catchment, for the period 1961–1990. The validated flood model was then used to generate flood hydrographs using projected rainfall based on a global climate model, GFDL, and a regional climate model, CCAM, for 2016–2045. Projected daily precipitation for the two contrasting periods were used to derive adjustment factors for a given frequency of occurrence. Two scenarios of land-use change were considered to evaluate the likely impact of land-use change. Results showed that future flood magnitudes are unlikely to increase for large flood events for the urban catchment. Further, land-use change would not significantly affect flood magnitudes for a given frequency of occurrence in the urbanised catchment. Key words climate change; land-use change; floods; Queensland, Australia ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 30-37. Synchronous linked changes in rainfall, floods and river channel changes in southeastern Australia since European settlement WAYNE D. ERSKINE1,2 1 School of Environmental and Life Sciences, The University of Newcastle, Ourimbah Campus, PO Box 127, Ourimbah NSW 2258, Australia 2 Environmental Research Institute of the Supervising Scientist, GPO Box 461, Darwin NT 0801, Australia [email protected] Abstract Synchronous, alternating, rainfall-driven, flood- and drought-dominated regimes have been previously identified in the flood record of many rivers in southeastern Australia over the last 200 years. During the wet phases, annual and summer rainfall, rainfall intensities and flood magnitudes are much greater than during the dry phases. Synchronous river channel changes have also been documented on many but by no means all rivers. The theory of alternating flood- and drought-dominated regimes was proposed as an explanation of these rainfall- and flood-driven channel changes where two different channel states were recognised. The purpose of the present paper is to show that these alternating wet and dry phases are not simply related to easily measured 12 changes in general circulation, such as ENSO or IPO, and that many river channels are so resilient due to protection by flood-tolerant vegetation that the threshold of channel stability is not exceeded by these regime changes. Sand-bed streams and rivers cleared of riparian vegetation after European settlement are the most sensitive to alternating regime changes. Synchronous, linked rainfall, flood and channel changes can only be recognised where active river management has not been practised in south- eastern Australia. Current channel states on some rivers have no historical or pre-historical analogue. Key words flood-dominated regimes; drought-dominated regimes; river sensitivity; river resilience; river recovery ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 38-44 . Effect of climate change on flood events as a major driver of nutrient transport in western Japan YUTA SHIMIZU & SHIN-ICHI ONODERA Graduate School of Integrated Arts and Sciences, Hiroshima University, 1-7-1, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan [email protected] Abstract This research aims to assess the effect of climate change on flood events as a major driver of nutrient discharge. It was found that small-scale flood events have decreased and extreme flood events have increased in western Japan. In addition, the frequency of discharge drought years decreased from the 1980s to the 2000s. The results imply that the runoff trend may have caused a flow regime shift. Accordingly, the capability for nutrient transportation during baseflow conditions has decreased. While the amount of nutrients can accumulate within the catchment during drought periods, large amounts of nutrients can be transported in the first flood event. It is like the first flush phenomenon in urban hydrology. It was found that the mean N:P ratio of the study catchment in Japan had increased in the recent decade. Although change of human activities may be one of the reasons, it is suggested that flow regime shift due to climate change may be an important driver. Key words nutrient transport; flood; extreme event; drought; SWAT model ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 47-52. Global climate change impacts on freshwater availability – an overview of recent assessments DIETER GERTEN Potsdam Institute for Climate Impact Research, Telegraphenberg A62, 14473 Potsdam, Germany [email protected] Abstract Global climate change will affect freshwater resources in manifold ways, requiring comprehensive assessments of key components of the water cycle – optimally in conjunction with vegetation and carbon dynamics intrinsically coupled to water dynamics. Here, some recent quantitative assessments of global climate change impacts on water availability and scarcity are presented, focusing on: (i) irrigation demand and (ii) “green” and “blue” water availability versus demand for producing a given diet. The reviewed studies are based on simulations with a dynamic global vegetation and water balance model, driven by climate change scenarios from 17–19 CMIP3 general circulation models. Moreover, outlooks are presented on CMIP5 projections and findings from the recently launched Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP), which makes use of a large suite of global hydrological and land surface models. It is shown that climate change will affect blue and green water demand and availability around the world, with countries especially in Africa and Asia likely to be affected so severely that they may no longer be able (or may remain unable) to produce certain diets on their own. More systematic studies are proposed that address both climate- and water-model structural uncertainty at the same time. They should be complemented by studies that investigate systematically the options to solve existing or emerging water scarcity problems. 13 Key words global hydrology; climate change; climate impacts; vegetation; food production; CO2 effects; uncertainty; water scarcity ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 53-59 . Post-processing of climate projections for hydrological impact studies: how well is the reference state preserved? J. DAHNÈ, C. DONNELLY & J. OLSSON Research & Development (Hydrology), Swedish Meteorological and Hydrological Institute, Norrköping, Sweden [email protected] Abstract Evaluations of the output of regional climate models (RCMs) used to simulate impacts of climate change on hydrology show strong biases for present climate, particularly for precipitation. Various methods are often used to correct these biases prior to any hydrological impact studies where RCM data are used to force a hydrological model (HM). Bias correction (BC) is considered a preferred method for interpreting climate change results because it conserves the changes in variability of precipitation predicted by the RCMs, while retaining a realistic representation of the volume. But, even though the RCM outputs are adjusted to match a reference dataset, the resulting outputs from a HM will not necessarily retain this close match. Traditionally, BC methods are validated in HMs by their ability to reproduce discharge and little work has been done to assess internal variables. This study addresses this by comparing how well a number of hydrological variables can be reproduced by a HM using bias-corrected forcing. The results showed that while BC succeeded in reproducing simulated runoff similar to the reference dataset, other variables including soil moisture, surface runoff, and snow depth and duration could not be reproduced. Key words RCM; bias correction; downscaling; distribution-based scaling; hydrology ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 60-66. Water supply capacity of a meso-scale Mediterranean catchment under climatic and anthropogenic changes LILA COLLET1, DENIS RUELLAND2, VALERIE BORRELL-ESTUPINA1, ALAIN DEZETTER3 & ERIC SERVAT3 1UM2, 2CNRS, 3IRD – UMR HydroSciences Montpellier, Place E. Bataillon, 34395 Montpellier Cedex 5, France [email protected] Abstract Assessing water supply capacity is crucial, notably in the Mediterranean region, identified as a hotspot of climate change and where water demands have been continuously increasing. The Hérault River catchment (France) is representative of this context since its discharge has undergone a significant decrease over recent decades. A modelling framework is proposed to assess the ability of the water supply to satisfy water demands over the last 50 years. The water supply was evaluated using a hydrological model and a dam management model. Dynamics of water demands were estimated for the domestic and agricultural sectors. A water supply capacity index was then computed to assess to what extent water demands have been satisfied at the sub-basin scale. Runoff dynamics are fairly well represented in both calibration and validation with the hydrological and the dam management models (Nash-Sutcliffe criteria above 0.8). Domestic demands have increased since the 1980s and are characterized by a seasonal peak in summer. Agricultural demands have been increasing in the driest portions of the watershed and decreasing in the wettest portions where the irrigated area has decreased. Although most water demands were highly satisfied from 1961 to 1980, water demands in downstream portions were frequently not satisfied in summer after the 1980s. Key words climate change; integrated modelling; water resources; water demand; water supply assessment; River Hérault ___________________________________________________________________________________________________ 14 Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 67-72 Evaluation and comparison of two downscaling methods for daily precipitation in hydrological impact studies J. CARREAU1, A. DEZETTER1, H. ABOUBACAR2 & D. RUELLAND3 1 IRD, 3 CNRS– UMR HydroSciences Montpellier, Place E. Bataillon, F-34395 Montpellier Cedex 5, France 2 Polytech’ Clermont-Ferrand–Université Blaise-Pascal, Clermont-Ferrand, France [email protected] Abstract This paper aims to evaluate and compare two downscaling methods for daily precipitation over the Ebro catchment in Spain (85 000 km2). The two downscaling methods are probabilistic and assume that the change in precipitation simulated by the climate model can be transferred to the distribution of the precipitation at the local scale. The first method is the perturbation method and serves as the benchmark against which CDF-t, a recently proposed downscaling method, is compared. The local data consist of 10 km 10 km grids of daily precipitation over the Ebro catchment. The large-scale data are outputs from two GCMs (ECHAM5 and CNRM-CM3) of the ENSEMBLES project under the baseline scenario for the 20th century. According to the availability of data, we defined a reference period over the years 1959–1978 and a study period over 1979–1998. Several variants of each downscaling method were compared on the study period. We designed three performance criteria which relate to important features of precipitation for hydrological modelling (similarity in distribution, seasonality and total precipitation). We provide an overview of the performance of the best variant of each downscaling method with both GCMs. Key words global climate models; perturbation method; CDF-t; Ebro catchment, Spain; impact studies; K-S statistic ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 73-79 Evaluation of two bias-corrected regional climate models for water budget simulations in a Mediterranean basin ZOUBEIDA BARGAOUI1, ASMA FOUGHALI1, YVES TRAMBLAY2 & AHMED HOUCINE1 1 Université de Tunis El Manar, Ecole Nationale d’ingénieurs de Tunis, Laboratoire de Modélisation en Hydraulique et Environnement, Tunisia [email protected] 2 IRD / HydroSciences-Montpellier, France Abstract This study seeks to assess runoff response to bias-corrected rainfall from regional climate models (RCM) using a water balance model. Hydrological data of observed rainfall time series and mean daily discharge observations at a basin outlet in northern Tunisia are available. In addition, meteorological data from three surrounding stations with air temperature, air pressure, wind speed, air relative humidity and sunshine length series are considered to estimate monthly potential evapotranspiration (ETP). RCM simulations of the SMH model driven by the ECHAM5 (SMH-E) and BCM (SMH-B) global climate models, provided by the European Union funded project ENSEMBLES are also considered for a control period, 1961–2000. The RCM rainfall outputs of the control period were corrected for bias by adjusting month by month the daily rainfall cumulative distributions, using a parametric quantile-mapping method with gamma distributions. A modified version of the single store water budget model BBH is considered, introducing soil texture information through pedotransfer parameters. Model parameters were calibrated using both observed runoff data at the basin outlet and the ratio of actual evapotranspiration to potential evapotranspiration. Considered as a basin signature, the latter is integrated in the calibration process. The water budget model is run at the daily time step successively with the daily observed rainfall and the daily bias-corrected RCM data series. Then, comparison of runoff impacts is performed examining simulated runoff and actual evapotranspiration statistics at the monthly resolution. It is found that simulated runoff and actual evapotranspiration responses are very similar. However, both models underestimate the runoff production during the winter season which raises the problem of water balance model calibration and validation with climate model data. Key words RCM; climate change; bias correction; impact studies; water budget; evapotranspiration 15 ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 80-85 Automated statistical downscaling in several river basins of the Eastern Monsoon region, China ZONGXUE XU, PIN LIU & WENFENG LIU College of Water Sciences, Beijing Normal University; Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100875, China [email protected] Abstract The tendency of global warming, as described by the IPCC (Intergovernmental Panel on Climate Change), will lead to changes in rainfall and other climate variables, which will be amplified in runoff. However, GCMs (global climate models) can only provide information at a coarse resolution and cannot be used directly in hydrological modelling. Statistical downscaling methods are used to fill the gap between large-scale climate change data and fine-scale hydrological applications. An Automated Statistical Downscaling (ASD) technique is adopted for a case study in three river basins of the Eastern Monsoon region, China. Results show that ASD is able to present seasonal variation of four variables during both calibration and validation periods. The efficiency of simulation for air temperature is better than precipitation due to the high degree of uncertainty within precipitation. Meanwhile, the performance of ASD model changes in different river basins, depending on geographic and meteorological factors in the study area; better simulation is obtained in areas with higher homogeneity. Key words climate change; Eastern Monsoon region; ASD; ERA-40; GCMs ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 86-91. Dramatic localised climate change effects on water resources DAVID MUNDAY1, IAN CORDERY2 & DALE RUBINSTEIN1 1 School of Civil an Environmental Engineering, University of NSW, Australia 2 School of Civil and Environmental Engineering, University of NSW, Sydney, NSW, 2052, Australia [email protected] Abstract In the southwest of Western Australia the precipitation and resulting surface runoff have declined dramatically in recent years. The surface runoff around Perth is now only 30% of previous volumes; however, in the surrounding regions to the north and east the water resources have been increasing. Over the same period, temperatures have increased by up to 3C over much of Australia; but in the southeast, where water resources changes are not apparent, the temperatures have declined by more than 0.5C in the last 100 years. These findings demonstrate that the causes of these dramatic changes in precipitation, water resources and even temperature are quite unclear and vary greatly across Australia. They clearly show a need for caution in discussion of global climate change and for great care in the selection of representative observations to permit the drawing of conclusions on a global and even a regional scale. Key words temperature rise; water resources decline; climate change ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 92-98 . Assessing the impact of land use/land cover and climate changes on water stress in the derived savanna AMIDU AYENI1, EVISON KAPANGAZIWIRI2, ALABI SONEYE1, SAJITH 16 VEZHAPPARAMBU3 & JIMMY ADEGOKE4 1 Department of Geography, University of Lagos, Lagos, Nigeria [email protected], [email protected] 2 HydroSciences Research Group, Natural Resources & the Environment, CSIR Pretoria, South Africa 3 Global Change & Ecosystem Dynamics Group, CSIR Pretoria, South Africa 4 Department of Geo-Sciences, University of Missouri, Kansas City, USA Abstract Understanding the impact of land use/land cover (LULC) and climate patterns on basin runoff is necessary in assessing basin water stress. This assessment requires long-term observed rainfall time series and LULC spatial data. In order to assess the potential water stress, the study used long-term (1981–2007) rainfall data to drive the Pitman monthly rainfall–runoff model to assess changes in runoff for three selected basins in Nigeria: Asa, Ogun and Owena. In spite of the limitations in the availability of spatio-temporal hydrometeorological data, the model results revealed commensurate increase in the runoff coefficient with decreases in forest cover between 1981 and 2000. Low runoff coefficients of 5.3%, 12.0% and 6.4% were recorded for Asa, Ogun and Owena basins, respectively, based on C-CAM projection of low rainfall for 2010–2050. These results indicated that in the future, water stress in Asa and Owena basins would be much higher, when compared with Ogun basin. Key words land-use/land-cover; climate change; rainfall; runoff; hydrological modelling; water stress; derived savanna; Nigeria ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) . 99-104 Impacts des changements globaux sur les ressources en eau dans la zone sahélienne en Afrique de l’Ouest TAZEN FOWE1, JEAN-EMMANUEL PATUREL1,2, HAROUNA KARAMBIRI1, HAMMA YACOUBA1, PIERRE DIELLO3 & GIL MAHE2,4 1 Institut International d’Ingénierie de l’Eau et de l’Environnement (2iE), Centre Commun de Recherche Eau et Climat, Laboratoire Hydrologie et Ressources en Eau, 01 BP 594 Ouagadougou 01, Burkina Faso [email protected] 2 IRD-HydroSciences Montpellier, Université Montpellier 2, Case courrier MSE, Place Eugène Bataillon, F-34095 Montpellier Cedex 5, France 3 Conseil Ingénierie et Recherche Appliquée, Bamako, Mali 4 Université Mohamed V-Agdal, Rabat, Maroc Résumé L’objectif de cette étude est d’évaluer les impacts du changement global sur les écoulements futurs dans le bassin supérieur de Nakanbé à Wayen au Burkina Faso dans une perspective de planification des ressources en eau. Il s’est agi dans un premier temps d’élaborer les scénarii climatiques et socio-économiques à l’horizon 2025 (période 2011–2040), ensuite de construire la série de l’évolution temporelle de la capacité de rétention en eau du sol et enfin de mettre en œuvre un modèle hydrologique (GR2M) en prenant en compte la dynamique environnementale. Les résultats révèlent une tendance à l’augmentation de la capacité du réservoir sol du modèle liée aux impacts des activités socio-économiques. En termes de pluviométrie et d’évapotranspiration annuelles, les projections des modèles climatiques régionaux (MCRs) utilisés varient respectivement dans une plage de –3 à +10% et +2 à +7% par rapport à la période de référence 1971–2000. La simulation hydrologique montre que les écoulements changeront plus ou moins fortement dans le futur avec les taux annuels situés entre –6 et +22%. Mots clefs ressources en eau; modélisation hydrologique; changement climatique; couvert et occupation du sol; Sahel Impacts of global changes on water resources in the Sahel of West Africa Abstract The objective of this study is to assess the impacts of global changes on the future runoff at the Wayen gauging station on the Upper Nakanbé River in Burkina Faso with a view of water resources planning. The specific objectives were to: (i) elaborate climate and socio-economic scenarios up to 2025 (period 2011–2040); (ii) Build the time series of soil water holding capacity; (iii) implement a hydrological model (GR2M) taking into account environmental change. The results indicated an increase of the soil reservoir capacity of the model linked to socio-economic impacts (intensive recovery of degraded soils). In terms of annual rainfall and evapotranspiration, the projections of regional climate models (RCMs) used vary respectively in a range from – 3 to +10% and +2 to +7% in relation to the reference period 1971–2000. According to the climate scenarios, hydrological simulation shows that flows will change more or less strongly in the future with the annual rate ranging from –6 to +22%. 17 Key words water resources; hydrological modelling; climate change; land cover/use; Sahel ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 105-110 . The impact of climate change on river flow in arid and semi-arid rivers in Algeria AYOUB ZEROUAL, MOHAMED MEDDI & SAFIA BENSAAD Higher National School of Hydraulics, Blida, Algeria [email protected] Abstract In Algeria, the problems of water resources have not been adequately treated till now, both in the analysis of climate change and in the formulation of climate policy. Similarly, in most cases, the historical evolution of climatic parameters and water resources has not been evaluated in different horizons and at different scales. In order to check this evolution, we selected the Algerian-Hodna-Soummam (AHS) basin that belongs to three different climate regions of Algeria, to evaluate the impact of future climate change on seasonal flows of 2050 and 2100. To better understand the importance of these impacts, we based our analysis on average flow of the reference period (1961–1990) and made comparisons to this. The methodology used is based on the GR2M model. The analysis of the results shows a marked decrease in average monthly flows compared to the reference period in the different horizons and the various studied scales. Key words climate change; river flow; Algeria ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 111-117 . Impacts of climate change on hydrology in the Srepok watershed, Vietnam DAO NGUYEN KHOI Faculty of Environmental Science, University of Science – Vietnam National University Ho Chi Minh City, 227 Nguyen Van Cu, Dist. 5, Ho Chi Minh City, Vietnam [email protected] Abstract An investigation was made of the impacts of climate change on hydrology in Srepok watershed, located in the central highlands of Vietnam, using the SWAT (Soil and Water Assessment Tool) hydrological model. The model was calibrated and validated using daily streamflow records. The calibration and validation results indicated that the SWAT model was able to simulate the streamflow reasonably, with Nash-Sutcliffe efficiency exceeding 0.72 for the Ban Don station, for both calibration and validation at daily and monthly steps. The hydrological response to climate change was simulated based on the calibrated model. The climate change scenarios were built by using a downscaling method (delta change method) based on the outputs of MIROC 3.2 Hires GCM driven by A1B and B1 emission scenarios. The results indicated a 1.3–3.9C increase in annual temperature and a 0.5 to 4.4% decrease in annual precipitation which corresponded to a decrease in streamflow of about 2.8 to 7.6%. The large decreases in precipitation and runoff are observed in the dry season. Key words climate change; hydrology; Srepok watershed, Vietnam; SWAT model ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 118-123. Dynamic modelling for assessing the impact of climate change on the hydrological regime of Chenab basin, NW Himalayas 18 A.S. JASROTIA1, DEEPIKA BARU2 & FARHA NISHAT2 1 Department of Geology, University of Jammu, Jammu – 180 006, India [email protected] 2 Department of Remote Sensing and GIS, University of Jammu, Jammu – 180 006, India Abstract The projection of future climate variables from 2011–2040 was done by using the Statistical Downscaling Model (version SDSM 4.2) to downscale daily maximum and minimum temperature, and daily precipitation at two stations, Dhyangarh and Baghliar, in the study area. The results of the downscaled maximum temperature reveal that there is increase in temperature for both A2 and B2 scenarios, but the increase is greater with the A2 scenario for both stations. Similarly, downscaled minimum temperature also shows an increasing trend for both these stations but the increase in average annual minimum temperature is greater for Dhyangarh station than Baghlihar for both the scenarios. The result of downscaled precipitation reveals that precipitation does not manifest a systematic increase or decrease in any future time horizon for either the A2 or the B2 scenario. Irrespective of the maximum and minimum temperature, there is a decreasing trend of precipitation at the beginning of the rainy season (May and June) and increasing trend towards the end of rainy season (September and October) in both the stations for both the A2 and B2 scenario. The results obtained from the HBV-EC model indicate that for Baglihar station, in June, July, August, there was a reduction in discharge by 4.0%, 5.3% and 5.5%, respectively, according to the A2 scenario, and of 2.8%, 4.4% and 5.2%, respectively, according to the B2 scenario for 2011–2040. For Dhyangarh station, the corresponding reductions are 4.2 %, 5.4% and 5.8%, according to the A2 scenario, and 3.9%, 5.1% and 5.5%, according to B2 for 2011–2040. Thus, the climate change shows the reduction of discharge in both the stations, but the reduction is more in the case of Dhyangarh station. Key words dynamic modelling; climate change; general circulation models; HBV-EC model; Chenab basin ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 124-130 . Drought risks and impact on water resources in part of northern Nigeria OLUSEGUN ADEAGA Department of Geography, University of Lagos, Nigeria [email protected] Abstract Knowledge concerning various aspects of drought and water scarcity is required to predict and to articulate strategies to minimize the effects of future events. This paper investigates drought episodes in northern Nigeria using the Standardized Precipitation Index (SPI) for monthly rainfall standardization at temporal scales of 6 and 12 months. The region has been hit by droughts with maximum severity in the 1980s. The Sahel savannah is more prone to extreme drought with great magnitude while the Guinea and Sudan savannah are more prone to mild to moderate drought. Hence, there is a call for people-oriented national drought policies and preparedness. Key words drought; northern Nigeria; rainfall; standardized precipitation index (SPI); recurrence interval ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 133-139. Embedding complex hydrology in the climate system – towards fully coupled climate–hydrology models MICHAEL BUTTS1, SØREN H. RASMUSSEN2,7, MARC RIDLER1, 19 MORTEN A.D. LARSEN3, MARTIN DREWS2,4, SARA LERER1,8, JESPER OVERGAARD1, JESPER GROOSS1, DAN ROSBJERG5, JENS H. CHRISTENSEN2 & JENS C. REFSGAARD6 1 DHI, Agern Alle 5, DK 2970, Hoersholm, Denmark [email protected] 2 Danish Meteorological Institute, Lyngbyvej 100, DK 2100 Copenhagen, Denmark 3 University of Copenhagen, Øster Voldgade 10, DK 1350 Copenhagen, Denmark 4 Technical University of Denmark, Frederiksborgvej 399, DK 4000 Roskilde, Denmark 5 Technical University of Denmark, DTU Miljø, DK 2800 Kgs. Lyngby, Denmark 6 Geological Survey of Denmark and Greenland (GEUS), Øster Voldgade 10, DK1350 Copenhagen K, Denmark 7 Now at EnviDan, Fuglebækvej 1A, DK 2770 Kastrup , Denmark 8 Now at Technical University of Denmark, DTU Miljø, DK 2800 Kgs. Lyngby, Denmark Abstract Motivated by the need to develop better tools to understand the impact of future management and climate change on water resources, we present a set of studies with the overall aim of developing a fully dynamic coupling between a comprehensive hydrological model, MIKE SHE, and a regional climate model, HIRHAM. The physics of the coupling is formulated using an energy-based SVAT (land surface) model while the numerical coupling exploits the OpenMI modelling interface. First, some investigations of the applicability of the SVAT model are presented, including our ability to characterise distributed parameters using satellite remote sensing. Secondly, field data are used to investigate the effects of model resolution and parameter scales for use in a coupled model. Finally, the development of the fully coupled climate–hydrology model is described and some of the challenges associated with coupling models for hydrological processes on sub-grid scales of the regional climate model are presented. Key words climate change; SVAT; hydrological modelling; land surface modelling; coupling; atmospheric feedbacks; remote sensing; MIKE SHE; HIRHAM ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 140-145 . Impact of groundwater dynamics and soil-type on modelling coupled water exchange processes between land and atmosphere BENJAMIN FERSCH1, SVEN WAGNER1, THOMAS RUMMLER2, DAVID GOCHIS3 & HARALD KUNSTMANN1,2 1 Karlsruhe Institute of Technology, Division for Meteorology and Climate Research, Department of Atmospheric Environmental Research (IMK-IFU), Kreuzeckbahnstr. 19, D-82467 Garmisch-Partenkirchen, Germany [email protected] 2 University of Augsburg, Institute of Geography, Universitätsstr. 10, D-86159 Augsburg, Germany 3 National Center of Atmospheric Research (NCAR), Research Applications Laboratory (RAL), PO Box 3000, Boulder, Colorado 80307-3000, USA Abstract Regional atmospheric models such as the Weather Research and Forecasting model (WRF) employ land-surface models (LSMs) that usually neglect the influence of the saturated zone. An inadequate representation of the interaction between the saturated and unsaturated zones, however, could lead to unrealistic soil-moisture and -temperature conditions and thus introduce limitations to accurately describing the evapotranspiration and planetary boundary layer processes, and consequently precipitation generation. We present a process study comparing two parameterization schemes for groundwater–soil-moisture interaction in the Noah-LSM against the standard free-drainage lower boundary. It serves as the foundation for a fully twoway coupled extension of the hydrological-atmospheric model system, WRF-Hydro.With the groundwater controlled lower boundary condition, depending on the soil-type, the resulting annual water budgets change by up to 20% for the volumetric water content of the top soil layer, by 6 to 67 mm for surface runoff, and by –10 to 75 mm for evapotranspiration. Key words groundwater; soil moisture; surface atmosphere feedback; coupled model; water budgets 20 ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013 146-151 Investigating the importance of groundwater for near surface flux and state simulation through a multi-constraint analysis of a complex surface–subsurface–atmosphere model SIMON STISEN, TORBEN OBEL SONNENBORG & JENS CHRISTIAN REFSGAARD Geological Survey of Denmark and Greenland, Øster Voldgade 10, 1350 Copenhagen K, Denmark [email protected] Abstract A complex distributed numerical modelling framework including both groundwater–surface-water flow and heat flux exchange with the atmosphere, combined with a unique observational data set, enables a comprehensive application of multiple independent constraints to the model parameter optimization at the catchment scale (1050 km2). Five independent observational data sets consisting of stream discharge, groundwater head, latent heat flux, soil moisture and remotely-sensed land surface temperature are the basis for formulating 11 objective functions focusing on the bias and RMSE of time series from multiple stations. A sensitivity analysis of 35 model parameters reveals that even surface fluxes and states, such as soil moisture, heat fluxes and land surface temperature, are highly sensitive to parameters that are typically associated with the groundwater components of the model. This indicates the importance of also using fully coupled modelling approaches in detailed studies of the near surface–atmosphere exchanges. Key words surface–subsurface–atmosphere model; sensitivity analysis; multi-constraint; groundwater; surface flux ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 152-157 . Hydrometeorological modelling for Poyang Lake region, China S. WAGNER1, B. FERSCH1, H. KUNSTMANN1,2, F. YUAN3, C. YANG3 & Z. YU3,4 1 Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research (IMK-IFU), Germany [email protected] 2 Institute of Geography, University of Augsburg, Germany 3 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, 1 Xikang Road, Nanjing 210098, China 4 Department of Geoscience, University of Nevada, Las Vegas, Nevada, USA Abstract Feedback mechanisms among the atmosphere, land surface and subsurface are important to understanding changes in the hydrological cycle due to climate and land-use changes. The quantification of these feedback mechanisms requires coupled modelling systems describing both the atmosphere and terrestrial hydrosphere. In our approach we couple the atmospheric model WRF and the hydrological model HMS. The research area is Poyang Lake basin (about 160 000 km2) in China. For the coupled WRF-HMS simulations, first stand-alone WRF simulations were performed to identify a suitable set-up for the target region. The bias is – 0.5°C for temperature and –26% for precipitation on the annual scale. Second, the performance of the newly implemented hydrological part of the model is investigated showing reasonable results. Third, coupled simulations were performed showing, so far, significant underestimations of observed streamflows. The potential of coupled atmospheric–hydrological modelling for investigations of the hydrometeorological fluxes due to climate and land-use changes at regional scales are discussed. Key words coupled atmospheric hydrological modelling; Poyang Lake, China; WRF; HMS 21 ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) . 158-164 A new curve for representing the spatial distribution of rainfall DWEEPENDRA N. KALITA L&T Power Development Ltd, 201, H L Wings, Sector-11, Dwarka, New Delhi-110075, India [email protected] Abstract The spatial variability of rainfall, an important element of the hydro-climatic regime, has been a comparatively difficult element to address. The availability of high-resolution gridded rainfall data in recent times is now offering new possibilities. Conceptually, in the line of the hypsometric curve, a curve can be drawn using the gridded rainfall data to represent the distribution of rainfall across the area of the catchment. It is proposed to call this curve the “hyetometric curve”. The use and potential of hyetometric curves are demonstrated by drawing such curves for the tributary catchments of the trans-Himalayan Arun basin that spans from China to Nepal. The hyetometric curve can aid in establishing hydrological similarity and framing catchment classification schemes. It makes computing the average rainfall of a catchment much easier. It has potential for use also in climate change studies. All these aspects are discussed in this paper. Key words rainfall; spatial variability; gridded data; hyetometric curve; Arun basin, Himalaya ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 165-170. Regional calibration against multiple data sources to predict streamflow J. VAZE, Y. ZHANG, F.H.S. CHIEW, B. WANG & J. TENG Water for a Healthy Country Flagship, CSIRO Land and Water, Canberra, ACT, Australia [email protected] Abstract This paper presents modelling experiments with three hydrological models to compare daily runoff predictions from regional calibration (where one set of parameter values are used to model an entire sub-region or region) and from regionalisation based on geographical proximity (where ungauged catchments are modelled using optimised parameter values from the closest gauged catchment). Data from 196 catchments across southeastern Australia are used, and the model is calibrated against observed runoff and remotely-sensed evapotranspiration and soil moisture. The results show that daily runoff predictions from the geographical proximity regionalisation are generally only slightly better than the runoff predictions from regional calibration. The results also show that calibration against multiple data sources only very marginally improves the runoff predictions compared to calibration against runoff alone. Nevertheless, these are early attempts, and the results suggest that regional calibration and modelling utilising multiple data sources have the potential to improve runoff predictions across large regions, as well as provide more parsimonious interpretation of parameter values for impact studies and more consistent simulations of the various fluxes and stores. Key words rainfall–runoff modelling; remote sensing; regional calibration; regionalisation ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 171-176 . Distributed hydrological modelling for estimation of hydrological dynamics in a karst region ZHICAI ZHANG, XI CHEN, YANFANG ZHANG & RUNRUN ZHANG 22 State Key Laboratory of Hydrology Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, China [email protected] Abstract Karstic geology and landforms, such as epikarst, underground channels and dolines or sinkholes, significantly influence hydrological processes. In this study, we improved the distributed hydrological model for a karst basin developed by Zhang et al. (2011) by adding computation of exchange between underground channel flow and surface water through dolines. A small karst basin located in Guizhou province of southwest China was selected for this hydrological simulation. The results show that the underground channel is a major passageway for groundwater discharge, and the underground channel flow hydrograph shows a sharp increase and decrease due to recharge from surface water through dolines. Key words karst; distributed hydrological model; doline; underground channel ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 177-182. Space–time variability of rainfall and hydrological trends in the Alto São Francisco River basin RICHARDE MARQUES DA SILVA1, CELSO AUGUSTO GUIMARÃES SANTOS2, MÔNICA LARISSA AIRES MACÊDO1, LEONARDO PEREIRA E SILVA2 & PAULA KARENINA DE MACEDO MACHADO FREIRE2 1 Federal University of Paraíba, Department of Geosciences, 58051-900 João Pessoa, PB, Brazil 2 Federal University of Paraíba, Department of Civil and Environmental Engineering, 58051-900 João Pessoa, PB, Brazil [email protected] Abstract The main objective of this study is to obtain a better understanding of the space–time variability of rainfall and trends of streamflow in the Alto São Francisco River basin using statistical tools. This basin covers one of the most important hydrological regions of Brazil and includes several states. A detailed statistical analysis applied to the river streamflow and rainfall time series of all gauges indicates that rainfall is highly temporally variable and there is a decrease in the annual rainfall amount for the period studied (1978−2007). The annual streamflow variation has a cyclic behaviour with a period length of approximately 10 years. In addition, a cross wavelet transform analysis between the monthly rainfall and reservoir inflows is applied, showing phase behaviour in all significant sections. However, there are no signs of any significant rainfall reduction in the basin, and in fact, some raingauges show a small rainfall increase during the recent decades. Key words streamflow; cluster; tendencies; hydrometeorology ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 183-190. Hydro-climatic variability in two Moroccan basins: comparative analysis of temperature, rainfall and runoff regimes KENZA KHOMSI1, GIL MAHE2, MOHAMED SINAN3 & MARIA SNOUSSI4 1 Direction de la Météorologie Nationale, cité de l’air, aéroport Casa Anfa, Maroc [email protected] 2 IRD et Université Mohamed V-Agdal, Rabat, Maroc 3 Ecole Hassania des Travaux Publics (EHTP) Km 7, Route d'El Jadida, BP. 8108, Casablanca, Maroc 4 Université Mohamed V-Agdal, Faculté des Sciences Département des Sciences de la Terre Rabat, Maroc Abstract The increase of temperature over Morocco, projected by climate models, should affect hydro-climatic regimes and ecological and socio-economic systems. In order to investigate the evolution of these regimes in the 23 large basins of Tensift and Bouregreg, we compared the trends of observed temperature, rainfall and runoff variability. Annual temperature time series show significant increasing trends ranging between 0.07 and 0.25°C per decade in both basins. Shifts in annual and monthly temperature trends were recorded between the mid1970s and mid-1980s and also in the early-1990s. In both basins, total annual rainfall decreased and changed its regime in the late-1970s, monthly rainfall regime changed only in the Tensift basin between early and mid1970s. Runoff in both basins showed no significant trend for most of the stations, but a consistent decreasing trend since the early-1970s in the Tensift basin and the late-1970s and the early-1980s in the Bouregreg basin. Significant hydro-climatic changes occurred first in the southern basin (Tensift). Ruptures are most frequent in the spring and summer monthly time series. Key words temperature; rainfall; runoff; hydro-climatic regime; variability; trend; rupture; Tensift; Bouregreg; Morocco ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 191-197 . Evolution et régionalisation des précipitations au nord de l’Algérie (1936–2009) SABRINA TAIBI1, MOHAMED MEDDI1, DOUDJA SOUAG2 & GIL MAHE3 1 Ecole Nationale Supérieure d’Hydraulique (ENSH), Blida, Algérie [email protected] 2 Université des Sciences et Technologie Houari Boumediene (USTHB), Bab Ezzouar, Alger, Algérie 3 IRD, Université Mohamed V, Rabat, Maroc Résumé Une analyse du régime pluviométrique du Nord de l’Algérie a été établie sur une période de sept décennies (1936–2009). Pour cela 102 séries pluviométriques ont été sélectionnées et soumises à cinq tests statistiques pour la détection de tendance ou de rupture. Une baisse significative des précipitations est observée à partir de la moitié des années 70 particulièrement dans la région Ouest (déficit pluviométrique entre 16 et 43%). L’indice pluviométrique standardisé a montré que les décennies 80 et 90 étaient les plus déficitaires. Ces résultats coincident dans l’ensemble avec les dates de rupture trouvées au Maroc. La régionalisation des précipitations par l’analyse en composantes principales a mis en évidence six régions homogènes. Ce découpage spatial montre aussi la vulnérabilité de chaque région au changement climatique. Mots clef changement climatique; précipitations; méthodes statistiques; régionalisation; Algérie ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 198-204 . Simplified methodology for floodplain inundation modelling using LiDAR DEM J. TENG, J. VAZE & D. DUTTA Water for a Healthy Country National Research Flagship, CSIRO Land and Water, GPO box 1666, Canberra, ACT, Australia [email protected] Abstract Flood inundation assessment is essential for emergency response under high flow conditions. It is also an important part of environmental planning and management. A simplified flood inundation modelling framework using LiDAR DEM is developed for rapid assessment of flood inundation area, volume and depth for high flow events. The LiDAR DEM is used together with climate and soil hydraulic data to simulate floodplain inundation area and volume for a given river stage height. The modelling methodology accounts for multiple flood runners as well as overbank flow onto the floodplain, and constrains the total spatial extent of inundation area based on maximum available water. It also accounts for floodplain evaporation, infiltration and return flows to the river. The methodology has been tested across several floodplain reaches in the Lower Murrumbidgee and Macquarie region in southeast Australia for estimating floodplain inundation extent and 24 volume for some recent flood events. The spatial inundation extents estimated using this newly developed methodology are compared to those derived from high resolution satellite imagery and on-ground measurements to assess the suitability and applicability of the method for inundation modelling. The estimated volume and depth are also compared to those from a fully distributed hydrodynamic model. The results indicate that the methodology is capable of providing reasonably good estimates of flood inundation spatial extent, volume and depth. This methodology can be easily implemented across a number of river reaches and therefore it can be used to carry out scenario modelling under various future climate conditions. Key words river reach; floodplain inundation; flooding; overbank flow; floodplain storage ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 205-212 . Building flood inundation modelling capability in river system models for water resources planning and accounting D. DUTTA, J. TENG, J. VAZE, J. HUGHES, J. LERAT & S. MARVANEK Water for a Healthy Country National Flagship, CSIRO Land and Water, Canberra, ACT, Australia [email protected] Abstract We have presented two conceptual approaches for building flood inundation modelling capability in river system models. The first approach is a simple method suitable for data limited environments. In this approach during any flood event, flow in a river reach within a floodplain is partitioned into two components, in-stream and overbank flow, based on the in-stream capacity. A flood volume-area relationship derived from the flood inundation time series, which is generated by analysing daily MODIS satellite imagery and SRTM DEM, is used to estimate flooded area for the overbank flow. The losses due to evaporation and groundwater seepage from the floodplain are calculated using the estimated flooded area. This approach can be integrated with a more detailed approach for flood inundation dynamics. This second approach is more comprehensive and suitable for areas with high resolution topography data such as LiDAR based data. LiDAR DEM is used to divide a floodplain into multiple storages based on pre-defined thresholds of flood inundation heights. The storage characteristics, including disconnected storage volume and hydraulic connectivity between floodplain storages and a river reach, are derived from the LiDAR DEM using a spatial data processing technique. This information is used to estimate flood inundation area for overbank flow. This paper introduces the two approaches and presents the results of their applications in the Murrumbidgee floodplain. The results are compared with the observed flow data and the hydrodynamic modelling results for two selected recent flood events. Key words flood inundation modelling; river system model; wetlands; LiDAR; Murray-Darling Basin; Murrumbidgee Basin; water resource planning; water resources accounting ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 215-220. GEWEX Land–Atmosphere Research: An Outlook PETER J. VAN OEVELEN1, JOSEPH A. SANTANELLO2, MARTIN BEST3, AARON BOONE4 & BART J.J.M. VAN DEN HURK5 1 International GEWEX Project Office, 10015 Old Columbia Road, Ste E-250, Columbia, Maryland 21046, USA [email protected] 2 NASA-GSFC, Building 33, Room G220, Greenbelt, MD 20771, USA 3 Met Office, Fitzroy Road, Exeter, Devon EX1 3PB, UK 4. Météo-France, CNRM/GMME/MOANA, 42 av. G. Coriolis, 31057 Toulouse Cedex, France 25 5 Royal Netherlands Meteorological Office (KNMI), PO Box 201, 3730 AE De Bilt, The Netherlands Abstract The Global Energy and Water EXchanges (GEWEX) project of the World Climate Research Programme (WCRP) has been focusing on Land–Atmosphere Research since the early 1990s. Whilst in the early days there was a strong emphasis on the use of global/Earth observational data sets, in later years the modelling of atmospheric processes and land–atmosphere interactions became increasingly important. The Global Land Atmosphere System Studies (GLASS) panel, in particular, has contributed extensively to land surface modelling activities leading to successful efforts such as the Project for the Intercomparison of LandSurface Parameterization Schemes (PILPS) for offline point-scale evaluation; and the Global Soil Wetness Project (GSWP-2) for the large global scale. Given the new research challenges in the coming years, the emphasis will be on land–atmosphere coupling, model data fusion and benchmarking. Key words land–atmosphere coupling; benchmarking; model data fusion; water; land; modelling; intercomparison ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 221-225 . A combined water and energy flux observation and modelling study at the TERENO-preAlpine observatory H. KUNSTMANN1,2, L. HINGERL2, M. MAUDER1, S. WAGNER1 & R. RIGON3 1 Institute of Meteorology and Climate Research (IMK-IFU), Karlsruhe Institute of Technology (KIT), Kreuzeckbahnstr. 19, 82467 Garmisch-Partenkirchen, Germany [email protected] 2 Institute of Geography, University of Augsburg, Augsburg, Germany 3 Department of Civil and Environmental Engineering, University of Trento, Trento, Italy Abstract Water and energy fluxes at and between the land surface/subsurface and the atmosphere are inextricably intertwined. In recent years, detailed observations of both water and energy fluxes in medium sized catchments became possible via new hydro-meteorological observatories like TERENO. This supports and enables the further development and evaluation of fully physically-based hydrological model systems that do not parameterize or even neglect specific parts of the energy balance and fluxes. We present results of a high resolution distributed modelling study based on the GEOtop model. It is applied to simulate both the water and energy balance and fluxes in the preAlpine environment of a medium size catchment in Bavaria, southern Germany, surrounding the TERENO-preAlpine test site, Fendt. Our simulations have a spatial resolution of 90 m and an hourly temporal resolution. We intercompare simulation results with observed streamflow measurements and energy flux observations obtained at an eddy-covariance tower. Key words water flux, energy flux; eddy-covariance measurements; high-resolution hydrological modelling; preAlpine terrain; TERENO ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 226-232 . Field and simulation experiments for investigating regional land– atmosphere interactions in West Africa: experimental set-up and first results JAN BLIEFERNICHT1, HARALD KUNSTMANN1,2, LUITPOLD HINGERL1, THOMAS RUMMLER1, SABINE ANDRESEN2, MATTHIAS MAUDER2, 26 RAINER STEINBRECHER2, RENÉ FRIEß1, DAVID GOCHIS4, URSULA GESSNER3, EMMANUEL QUENSAH6, AYOOLA AWOTUSE6, FRANK NEIDL2, CARSTEN JAHN2 & BOUBACAR BARRY5 1 Chair for Regional Climate and Hydrology, University of Augsburg, Universitätsstraße 10, 86159 Augsburg, Germany jan.bliefernicht.geo-uni-augsburg.de 2 Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Germany 3 German Aerospace Centre, Earth Observation Center, German Remote Sensing Data Center, Land Surface, Germany 4 National Center for Atmospheric Research, United States 5 International Water Management Institute, Burkina Faso 6 Graduate Research Program on the West African Climate System, Federal University of Technology Akure, Nigeria Abstract West Africa is characterized by strong land surface changes due to various anthropogenic activities which influence the spatiotemporal patterns of hydro-meteorological fluxes and which might alter the availability of water resources. To investigate these questions, we use a novel two-way coupled atmospheric– hydrological model that allows for a consistent and dynamic simulation of regional land–atmosphere interactions in mesoscale river basins. This model is adapted stepwise for the West African Sudanian Savannah, focusing on a main tributary of the White Volta. In addition, the experimental set-up of three micrometeorological stations using the eddy covariance technique is illustrated; they have been recently established in this region along a gradient of increasing agricultural activity. First measurements and simulation outcomes from the adaption of the atmospheric model are promising, but further model adaptation is crucial for a reliable simulation of surface fluxes on a daily or finer temporal scale. Key words land–atmosphere interactions; coupled atmospheric–hydrological simulations; Weather Research and Forecasting model; land surface model; eddy covariance stations; hydro-meteorological fluxes; precipitation; West Africa ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 233-238 . Updated vegetation information in high resolution WRF simulations JOAKIM REFSLUND1, EBBA DELLWIK1, ANDREA N HAHMANN1 & EVA BOEGH2 1 DTU Wind Energy, Frederiksborgvej 399, DK-4000 Roskilde, Denmark [email protected] 2 Roskilde University, Universitetsvej 1, 02, DK-4000 Roskilde, Denmark Abstract Climate studies show that the frequency of heat wave events and above-average high temperatures during the summer months over Europe will increase in the coming decades. Such climatic changes and longterm meteorological conditions will impact the seasonal development of vegetation and ultimately modify the energy distribution at the land surface. In weather and climate models it is important to represent the vegetation variability accurately to obtain reliable results. The weather research and forecasting (WRF) model uses green vegetation fraction (GVF) time series to represent vegetation seasonality. The GVF of each grid cell is additionally used to scale other parameters such as LAI, roughness, emissivity and albedo within predefined intervals. However, the default GVF used by WRF does not reflect recent climatic changes or change in management practices since it was derived more than 20 years ago. In this study, a new high resolution GVF product based on MODIS images is applied in a high resolution WRF simulation over Denmark during the 2006 heat wave year. It is found that the GVF is very different in a heat wave year compared to the default GVF. The simulation is compared to a control run using the default GVF data and their performances are quantified against gridded data. The verification includes 2-m temperature and precipitation. The results show that although the simulation using the new GVF product performs well, it does not significantly improve performance compared to the default GVF, despite significant differences in vegetation fractions. Key words green vegetation fraction; WRF; heat wave 27 ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 239-245. The heat flux from the land surface during the pre-monsoon season in the inland region of Thailand MASASHI KIGUCHI1, SHIN MIYAZAKI2,3, WONSIK KIM4, SHINJIRO KANAE5, TAIKAN OKI1, JUN MATSUMOTO6 & TAKEHIKO SATOMURA7 1 Institute of Industrial Science, the University of Tokyo, 4-6-1 Komaba, Meguro-ku, 153-8505, Tokyo, Japan [email protected] 2 Arctic Environment Research Center, National Institute of Polar Research, Japan 3 Research Institute for Global Change, Japan Agency for Marine Earth Science and Technology, Japan 4 National Institute for Agro-Environmental Sciences, Japan 5 Tokyo Institute of Technology, Japan 6 Tokyo Metropolitan University, Japan 7 Graduate School of Science, Kyoto University, Japan Abstract The heat flux during the pre-monsoon period in the inland area of Thailand is investigated using wind and moisture fields and sensible and latent heat flux from the NCEP/NCAR (the National Centers for Environmental Prediction/National Center for Atmospheric Research) re-analysis, precipitation and OLR (Outgoing Long wave Radiation) data for 2003. From middle or late March, before the monsoon onset, the latent heat flux is continuously dominant and the land condition is wet. The composite analysis of the intermittent dominance of the latent heat flux in February shows that the dominant area of the latent heat flux extends over southern China, the inland area of Thailand and Cambodia. The trough is analysed in the upper troposphere. The precipitable water increases, centering on the inland area of Thailand. It is suggested that evaporation from the land surface contributes to the moist condition of the atmosphere. However, the latent heat flux does not increase until the onset of the summer monsoon over India and the central part of Myanmar. The properties of the heat flux from the land are not similar to those over the Asian monsoon area during the premonsoon period. Key words latent heat flux; sensible heat flux; the Indochina Peninsula; NCEP/NCAR re-analysis data; OLR ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 246-252 . Effects of soil moisture on a summertime convective rainfall over a mountainous area and its contiguous plain in central Japan KAZUYOSHI SOUMA1, KENJI TANAKA2, TADASHI SUETSUGI1, KENGO SUNADA1, EIICHI NAKAKITA2, KAORU TAKARA2 & SATORU OISHI3 1 International Research Center for River Basin Environment, University of Yamanashi, 4-3-11 Takeda, Kofu, Yamanashi 400-8511, Japan [email protected] 2 Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan 3 Research Center for Urban Safety and Security, Kobe University, 1-1 Rokkodai-cho, Nada-ward, Kobe, Kobe 657-8501, Japan Abstract In this study, two numerical experiments of convective rainfall observed on 15 August 2001, in central Japan, were conducted using a cloud-resolving, land–atmosphere coupled model to investigate the effect of initial soil moisture on short-term weather phenomena. The first experiment, called WET, used the wettest soil condition observed in August 2001 as the initial soil moisture value. The other experiment, called DRY, used the driest condition in August 2001 as its initial soil moisture value. A comparison of the results for WET and 28 DRY showed that a drier soil-moisture condition led to higher rainfall over both the mountainous region in central Japan and Nobi Plain. Greater differences in rainfall amounts were found over the plain than over the mountainous region. The difference in near-surface convergence and atmospheric stability caused by local circulation was found to play an important role in transmitting the variation in soil moisture to rainfall. Key words soil moisture; summertime convective rain; cloud-resolving model, land-atmosphere interaction ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 253-259 . Observed variations in the Indian monsoon hydroclimate during recent decades M.V.S. RAMA RAO, J. SANJAY & R. KRISHNAN Centre for Climate Change Research, Indian Institute of Tropical Meteorology, Pune 411008, India [email protected] Abstract Detection of anthropogenic influences on regional hydroclimate often tends to be obscured by internal variations of the climate system. Using observed climate records and 20th-century re-analysis, we have examined the dominant modes of variability and trends in the Indian monsoon hydroclimate during recent decades. The present analysis extracts the internally-driven signals and the externally forced trends in the monsoon hydroclimate over the Indian subcontinent. It is seen that the internal variations in precipitation minus evaporation (P – E) over the Indian monsoon region are largely related to interannually varying patterns of sea surface temperature (SST) in the tropical Indo-Pacific basins. By separating the internal component of monsoon hydroclimate variability, it is seen that the emerging pattern of P – E change reveals a significant contribution of the forced trends over the Indian subcontinent. To gain further insight into the forced changes in the P – E history during recent decades, we have conducted a detailed integrated analysis of the three-dimensional moisture budget. Key words Indian monsoon hydroclimate; natural and forced trends; moisture budget; anthropogenic effect ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 260-265 . Investigation of urban-induced rainfall in Porto Alegre, Brazil, using TRMM satellite rainfall estimation CESAR FENSTERSEIFER1, DANIEL ALLASIA1,2, JEAN FAVARETTO1, RAVIEL BASSO1, RUTINÉIA TASSI1,2 & ANDRE L. SILVEIRA3 1 Programa de Pós-graduação em Engenharia Civil, Universidade Federal de Santa Maria, UFSM - Av. Roraima nº 1000 Cidade Universitária - Bairro Camobi - Santa Maria - RS - CEP: 97105-900, Brazil [email protected] 2 Programa de Pós-graduação em Engenharia Ambiental, UFSM, Brazil 3 Instituto de Pesquisas Hidráulicas, Universidade Federal do Rio Grande do Sul Abstract Traditional rainfall networks have deficiencies in quantitative representation of rainfall over larger or complex areas without an extensive and expensive system, which is normally not available in developing countries such as Brazil. In the city of Porto Alegre, an experimental network of 14 raingauges showed large differences in rainfall throughout the city that were linked to Urban-Induced Rainfall (Silveira, 1997). Due to the lack of other raingauges in the region, TRMM satellite rainfall estimation has been explored to verify the observed patterns and evaluate impacts of spatial heterogeneity. The results have shown statistically significant 29 differences in the maximum precipitation throughout the city, with differences in mean annual precipitation of 100 mm, and 20% differences in the maximum daily rainfall ever registered, confirming previous results, but have also shown regional patterns that converge in the city region. From the results, it is clear that TRMM data are a good complementary information source to traditional systems of measurement for assessing spatial variation in rainfall allowing extending information for ungauged areas of the city. Key words rainfall; TRMM; urban area ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 266-271 . Modelling and analysis of the impact of urban irrigation on land surface fluxes in the Los Angeles metropolitan area POUYA VAHMANI1 & TERRI S. HOGUE1,2 1 Department of Civil and Environmental Engineering, University of California Los Angeles, California, USA [email protected] 2 Department of Civil and Environmental Engineering, Colorado School of Mines, Colorado, USA Abstract The current work includes developing and integrating an irrigation module within the Noah LSMSLUCM (Single Urban Canopy Model) modelling framework. The model is run over a 49-km2 urban domain in the Los Angeles metropolitan area at a high resolution (30 m) to understand the temporal variability and spatial heterogeneity of urban energy and water fluxes. The irrigation scheme developed is calibrated using residential water-use data and estimates of outdoor water consumption. Our results indicate that updating soil moisture to 75% of field capacity at a 6-day interval reasonably represents irrigation over this study region. To validate the model performance, we introduce a systematic evaluation process using MODIS-Landsat ET and Land Surface Temperature (LST) products as well as CIMIS- (California Irrigation Management Information System) based landscape ET observations. We conclude that addition of an irrigation scheme is critical to adequately simulate urban hydrological cycles, especially in arid and semi-arid regions. Key words Noah; UCM; modelling; urban irrigation; land surface temperature; evapotranspiration ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 272-277 . Evapotranspiration and heat fluxes over a small forest – a study using modelling and measurements ANDREY SOGACHEV1, EBBA DELLWIK1 & EVA BOEGH2 1 Wind Energy Department, Technical University of Denmark, Roskilde, Denmark 2 Department of Environmental, Social and Spatial Change, Roskilde University, Denmark [email protected], [email protected] Abstract Some forests in Europe are too small to fulfil the strict fetch requirements associated with idealized flux observations. As a consequence of limited fetch, the flux measured above the canopy will often deviate from the source strength underlying the measurements. Because such flux measurements are very often used for calibration of forest parameters or model constants, further use of these parameters without a proper interpretation in mesoscale or global circulation models can result in serious bias of estimates of modelled evapotranspiration or heat fluxes from the given area. In the present work, we apply the atmospheric boundary layer (ABL) model SCADIS with enhanced turbulence closure including buoyancy for investigation of the spatial distribution of latent and sensible heat vertical fluxes over patchy forested terrain in Denmark during selected days in the summer period. The approach used can be utilized in interpretation of already existing 30 experimental data and in the planning of future experiments. Key words latent flux; heat flux; atmospheric boundary layer; modelling; heterogeneous surface ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013 278-282 Soil and canopy energy balances in a maize field with subsurface drip irrigation HANIEH KOSARI1, HOSSEIN DEHGHANISANIJ2, FARHAD MIRZAEI1 & ABDOLMAJID LIAGHAT1 Dept of Irrigation and Reclamation Engineering, Agricultural and Natural Resources Campus, University of Tehran, Karaj, Iran [email protected] 2 Agricultural Engineering Research Institute, Karaj, Iran Abstract Research was conducted at the experimental station of the Agricultural Engineering Research Institute (AERI), Karaj-Iran, on a maize field under subsurface drip irrigation during summer 2009. Bowen ratio techniques (BREB) were used to obtain the field energy balance and soil surface energy balance, including the total latent heat flux (λE) and soil surface latent heat flux (λEs). Accompanying other measurements resulted in four energy balance components at the field level (Rn, G, H, λE) and soil surface level (Rns, G, Hs, λEs). The energy balance components at canopy level (Rnc, Hc, λEc) were then calculated based on the difference between the corresponding values at field level and the soil surface. Data for the BREB method were collected from above canopy level, at canopy level and at the soil surface. Daytime averages of energy balance components in terms of (w/m2) were calculated. During the measurement period, net radiation values ranged between 304 to 333 w/m2, and net radiation reaching the soil surface ranged between 67 to 107 W/m2. The Rns values decreased with crop growth and LAI increase later in the crop development period. It was shown that λE accounted for 62–83% of Rn and λEs accounted for about 57–71% of Rns in subsurface drip irrigation. Results for a sample day showed that, of the total available energy for evapotranspiration, only 15% was used as sensible heat while the rest was used for evapotranspiration. The soil heat flux was less than 10% of net radiation, of which 93% of available energy was used for soil evaporation. At canopy level, about 19% of the available energy was used as sensible heat. ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 283-288 . Assessing climate change induced modification of Penman potential evaporation in the middle reaches of Huai River basin, China SHULEI ZHANG1, HAISHEN LÜ1, MANHHUNG LE1, WENJUN CHOU2 & YONGHUA ZHU1 1 State Key Laboratory of Hydrology-Water Resources and Hydraulics Engineering, Hohai University, Nanjing 210098, China [email protected] 2 Colleges of Harbour, Coastal and Offshore Engineering, Waterway and Harbour Engineering, Hohai University, Nanjing 210098, China Abstract Potential evaporation (Ep) is influenced by meteorological variables such as net radiation, wind speed, vapour pressure and air temperature. An attribution analysis was performed using the Penman formulation to quantify the contribution of each input variable to overall trends in Ep in the middle reaches of Huai River basin 31 from 1960 to 2011. The results show that the Ep presented positive and negative trends during 1960–1970 and 1971–2011, respectively, which resulted in a slight overall decreasing trend from 1960–2011. The result of the research here uncovers the fact that Ep rates did not necessarily increase in correspondence with mean air temperature over the past few decades. It is critical to take all the factors driving Ep into consideration, and this will continue to be so as climate change continues. Key words potential evaporation; climate change; attribution analysis ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 289-294 . Drought frequency analysis in China using a 55-year dataset of reconstructed soil moisture Z.Y. WU1,2,3, X.Y. LI1,2 & G.H. LU1 1 National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety, Hohai University, Nanjing, China [email protected] 2 College of Hydrology and Water Resources, Hohai University, Nanjing, China 3 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing, China Abstract Drought is a recurring hydroclimatic event. In recent years, drought has become a frequent natural hazard in China with one severe drought event in every two years, causing great losses to society. Therefore, it is important to study drought frequency in China. Since soil moisture is a key factor in revealing the whole process of drought occurrence, a 55-year dataset of reconstructed daily soil moisture was used to calculate the soil moisture anomaly percentage index (SMAPI), a drought index, and to perform drought frequency analysis in China. The Variable Infiltration Capacity (VIC) model with a resolution of 30 km 30 km was used for the soil moisture reconstruction and was run from 1956 until 2010. This study focuses on the spatial distribution and variability of drought frequency in China. Trends in drought occurrence is analysed using the Mann-Kendall (MK) method. The results indicate that the drought frequency in eastern China is higher than that in western China. Several regional drought centres are identified in southeast Inner Mongolia, the northeast areas of Inner Mongolia, the northeast China region, the H-H-H (Huang-Huai-Hai) region and southwest Tibet. In terms of seasonal distribution, summer and autumn droughts are more frequent than spring and winter droughts. The MK trend test shows the four seasons’ drought frequency shares the same changing pattern at the national scale, and is similar to that of annual drought. Key words soil moisture anomaly percentage index; drought frequency; season drought frequency; trend analysis ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 295-301 . Potential evapotranspiration, SPI, SPEI and surface humidity change over China during 1961–2011 WEN WANG, RENGUI XU & XI CHEN State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, China [email protected] Abstract Using monthly meteorological observation data at 649 sites in China for 1961–2011, potential evapotranspiration (PET), standardized precipitation index (SPI), standardized precipitation evapotranspiration index (SPEI) and land-surface humidity changes are investigated. PET calculated using the Priestley-Taylor formula shows that the southeast half of China, mostly humid to semi-humid areas, exhibits a significant decrease in PET, whereas the northwestern half of China, mostly arid to semi-arid, exhibits significant increase. SPI and SPEI exhibit different spatial and temporal characteristics over China, in some parts even presenting opposite directions of changes, especially on the Tibetan Plateau where SPI shows a decrease in drought severity but 32 SPEI shows an increase in drought severity. There was no significant change in humidity in most parts of China, except in the northwest, and on the central and northeastern Tibetan Plateau where significant increase in humidity is detected. However, there was a significant decrease in the area of the hyper-arid zone and a significant increase in the area of the semi-arid zone in the past 51 years. Key words potential evapotranspiration; standardized precipitation index; standardized precipitation evapotranspiration index; land-surface humidity; drought ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 303-308 . Modification of the standardized precipitation evapotranspiration index for drought evaluation MINGWEI MA1,2, LILIANG REN1,2, HE MA2, SHANHU JIANG1,2, FEI YUAN1,2, YI LIU1,2 & XIAOLI YANG1,2 1 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, No.1 Xikang Road, Nanjing, 210098, P. R. China [email protected] 2 College of Hydrology and Water Resources, Hohai University, No.1 Xikang Road, Nanjing, 210098, China Abstract Deficiencies of the standardized precipitation evapotranspiration index (SPEI) were identified. Using monthly precipitation, temperature and soil available water capacity datasets, we generated a new standardized water balance-derived index (SWBI) through a moisture departure probabilistic approach. The moisture deficit/surplus was calculated at different temporal scales and several techniques were used to adjust the time series to a generalized extreme value distribution. Comparisons of historical records of multiple indices show that the SWBI is highly consistent and correlated with the corresponding SPEI and self-calibrated Palmer drought severity index. The SWBI is most robust and preferable to the SPEI in spatial consistency and comparability, and it combines the simplicity of calculation with sufficient accounting for the physical nature of water supply and demand relating to droughts, all making it promising to serve as a competent alternative and reference to drought monitoring and assessment. Key words drought analyses; multiple indices; water balance; probability distribution; standardized index ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 311-319 . An approach for transient consideration of forest change in hydrological impact studies PAUL SCHATTAN1,2, MASSIMILIANO ZAPPA1, HEIKE LISCHKE1, LUZI BERNHARD1, ESTHER THÜRIG1 & BERND DIEKKRÜGER2 1 Swiss Federal Research Institute WSL, Zürcherstrasse 111, CH-8903 Birmensdorf, Switzerland [email protected] 2 University of Bonn, Department of Geography, Meckenheimer Allee 166, D-53115 Bonn, Germany Abstract An approach for exploring the impacts of climate change on tree migration and on the natural water balance of two large Swiss catchments (Rhône and Ticino) has been developed. We run the spatio-temporal forest model TreeMig for the period 1400–2100 with climate input from observations and from the A1B Scenario ECHAM5-REMO (from the “ENSEMBLES”-Suite). We post-processed the outcomes of TreeMig concerning forest biomass and leaf-area-index (LAI) and modified the forest coverage and LAI used in the hydrological model PREVAH. Every fifth computational year, forest coverage and LAI have been updated. 33 PREVAH has been recently used to assess climate change impacts on water resources for the whole of Switzerland for the control period 1980–2009 and for the scenario periods 2021–2050 and 2070–2099. Analyses show a degradation of forest for the 2070–2099 period in the lowest elevation ranges (<1200 m) as a result of increased drought stress. This results in lower LAI, reduced interception and increased discharge as compared to a baseline run without implementation of forest scenarios. For elevation ranges above 1500 m, TreeMig predicts higher biomasses and LAI. The simulated tree-line elevation might increase by up to 200 m. PREVAH computes in these areas higher evapotranspiration and less runoff as compared to the baseline run. Consideration of forest change yields in both areas changes in simulated discharge of –5 to –10 mm per year and changes in evapotranspiration of +5 to +10 mm per year. However, changes at specific elevation bands are up to four times higher. Key words hydrological impact modelling; forest change scenarios; European Alps ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 320-326 . An approach of coupling topographic indices to dynamic ecosystem modelling JING TANG & PETTER PILESJÖ Department of Physical Geography and Ecosystem Sciences, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden [email protected] Abstract The dynamic ecosystem model LPJ-GUESS combines sophisticated plant physiological and biogeochemical processes and has been successfully used in predicting vegetation dynamics at different scales. However, the water cycling is limited to vertical water movement between the atmosphere–plant–soil. Thus we have developed an enhanced version of LPJ-GUESS (called LPJ-DH) by coupling water routing and lateral water fluxes. The fundamentals are based on the spatial variability of topographic indices, calculated from digital elevation models (DEM). The runoff outputs from LPJ-DH and LPJ-GUESS were compared and the newly introduced hydrology scheme showed a possible advantage in representing the drainage network and topographic effects on water redistribution. The general increase of plant transpiration was also found over the catchment by LPJ-DH, and we demonstrated that the plant transpiration modelled by LPJ-DH was in line with observed data. Overall, the study demonstrated the feasibility and advantages of incorporating topographic effects on water redistribution within the frame of LPJ-GUESS. Key words surface runoff; LPJ-GUESS; LPJ-DH; topographic index ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 327-332. Deforestation impacts on discharge of the Ji-Paraná River – Brazilian Amazon DÉBORA MISSIO BAYER & WALTER COLLISCHONN Instituto de Pesquisas Hidráulicas, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500 CEP 91501970, Caixa Postal 15029, Porto Alegre, RS, Brazil [email protected] Abstract Hydrological impacts of land-use changes have been studied for several decades in relatively small basins using the paired catchment experimental approach. In large river basins this kind of experiment is of limited use, and the assessment of impacts can only be done by applying physically-based hydrological models. We analysed impacts of deforestation on streamflow of the river Ji-Paraná (southern Amazon) using the MGBIPH hydrological model. Three forest cover scenarios were simulated: pristine condition with predominant (~100%) forest cover; current condition with about 57% deforestation; and a hypothetical 100% deforestation scenario. Results suggest that average annual discharge of the river Ji-Paraná increases by about 31 mm for each 10% of the basin drainage area that is deforested. These results are consistent with worldwide experimental studies, but are not verified in observed streamflow records of the Ji-Paraná River. 34 Key words land use change; MGB-IPH model; distributed hydrologic model ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 333-339. Climate changes and their major impacts on environmental conditions of a freshwater Brazilian wetland RUTINEIA TASSI1, JUAN MARTIN BRAVO2, ADOLFO VILLANUEVA3, DAVID DA MOTTA MARQUES2, DANIEL ALLASIA1 & LUCAS TASSINARI1 1 Department of Sanitary and Environmental Engineering – Federal University of Santa Maria, Brazil [email protected]; [email protected] 2 Hydraulics Research Institute – Federal University of Rio Grande do Sul, Brazil 3 Flatlands Hydrology Institute – Buenos Aires Mid-province University, Argentina Abstract This study presents an analysis of how climate change scenarios may affect environmental conditions of a Brazilian freshwater costal wetland (Taim Wetland). Taim Wetland covers approximately 315 km2 and has a rich biodiversity. Considering two climate changes emission scenarios and different Atmospheric/Ocean General Circulation Models (AOGCMs), time series of projected temperature and precipitation were estimated by using the delta change approach. These time series were used as input to a pseudo-2D full hydrodynamic cell model, previously calibrated and validated, giving projected water level time series as results. A pattern of increase of water level was observed in both climate change scenarios. The water level time series were also compared to Ideal Water Level requirements established for key local species based on the habitat suitability index (HSI). Through this comparison it was estimated that a great number of key species would be directly affected due to reduction or even elimination of their habitat areas. Key words climate change; wetland; environmental conservation; habitat suitability index ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 340-345 . Catchment fragmentation and hydro-ecological modification of a raised bog wetland S. REGAN & P. JOHNSTON Department of Civil, Structural and Environmental Engineering, Trinity College Dublin, Ireland [email protected] Abstract The occurrence of ecological communities of conservational value on the surface of raised bog wetlands requires that specific hydrological conditions are maintained. Marginal drainage, in the past 20 years, of Clara Bog, Ireland, has resulted in dramatic morphological changes. Differential peat consolidation has fragmented what was one high bog topographic catchment area into four distinct catchment areas. Runoff has reduced by ~40% from the original main catchment area and there has been a ~26% decrease of wet areas supporting growth of Sphagnum moss species. In undisturbed bog systems the recharge rate of water seeping through the bog body to the regional groundwater table is in the order of 40 mm/year. The downward seepage rate in Clara is between 90 and 140 mm/year. A reduction in pore water pressure, due to drainage of the regional groundwater table, has induced excess water loss from the peat substrate, resulting in hydroecological modification of the bog surface. Key words hydroecology; subsidence; catchment; water balance; Ireland; peat bog ___________________________________________________________________________________________________ 35 Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 346-351 . Investigating discharge and rainfall variability in an Amazonian watershed: Do any trends exist? ALPHONCE C. GUZHA1, RODOLFO NOBREGA1, CELSO A. G. SANTOS2 & GERHARD GEROLD1 1 Georg-August-University, Institute of Geography, Landscape Ecology Department, Goldschmidtstr. 5, D-37077 Goettingen, Germany [email protected] 2 Department of Civil and Environmental Engineering, Federal University of Paraíba, 58051-900 João Pessoa, PB, Brazil Abstract A trend analysis of stream discharge from the upper Mortes watershed, southern Amazon, was performed using discharge and rainfall data in order to investigate the temporal variability of stream discharge, and relate it to associated rainfall variability. Non-parametric tests were done on daily, seasonal and annual discharge data. Frequency analysis using wavelet transform was also done. Results indicate increasing trends in discharge. The wavelet analysis identified dry periods; i.e. 19671975, 19821986 and 1993, which were followed by wet periods. In some cases, discharge increases could not be satisfactorily correlated to the rainfall. Further interpretation of the data for possible causes of streamflow changes is needed and discussion of the implications of these results in the context of climate change, deforestation and water resource management. Key words trend analysis; streamflow; rainfall; Mann-Kendall test; wavelet transform ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 352-357 . Decisions on land conservation practices in a semi-arid region considering hydrological and social drivers HUGO M. ALCÂNTARA1, JOHN E. B. L. CUNHA1, CARLOS O. GALVÃO1 & ITAMARA M. L. M. TAVEIRA2 1 Federal University of Campina Grande – UFCG, Campina Grande, Brazil [email protected] 2 Water Management Agency of the State of Paraiba – AESA, João Pessoa, Brazil Abstract In tropical regions, such as the Brazilian semi-arid zone, climatic and hydrological regimes are highly variable. This variability is a determinant for defining land occupation, but farmers’ social and economic characteristics are also important. This paper presents results of an investigation of hydrological and sediment yield from one small catchment due to land-use changes, considering both climatic and human factors. The study analysed observed time series of rainfall, runoff and sediment yield from an experimental catchment, and information from farmer interviews. The results show that clusters of a few intense events in a year determine annual runoff and sediment yield. The selection of land conservation practices can be aided by hydrological modelling based on information about farmers’ willingness to adopt land conservation practices and on their farms’ production systems and location within the catchment. Key words semi-arid; SWAT; land use; remote sensing ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 358-363 . Hydrological non-stationarity in southeastern Australia 36 NICHOLAS J. POTTER, LU ZHANG, CUAN PETHERAM & FRANCIS H. S. CHIEW CSIRO Water for a Healthy Country National Research Flagship, CSIRO Land and Water, GPO Box 1666 Canberra, ACT 2601, Australia [email protected] Abstract The Millennium Drought in southeastern Australia (SEA) from the mid-1990s until 2009 had large reductions in runoff. Significant changes in the runoff coefficient in many catchments occur with considerable over-prediction of runoff during drought, due to rainfall–runoff model calibration to pre-drought data. We consider this modelling bias as an incidence of hydrological non-stationarity, so that rainfall–runoff models may not be suitable for modelling runoff under future, drier climate projections. Natural responses of catchments to prolonged droughts, such as reductions in groundwater levels, and changing vegetation characteristics can affect runoff generation. Furthermore, over time there has been a substantial increase in the density and volume of farm dams in certain regions of SEA. These processes are typically conceptualised poorly in rainfall–runoff models, and are likely causes for non-stationarity. We relate runoff bias to catchment characteristics and calibrated model parameters, and explore the response of catchments in SEA to wetter conditions post-2010. Key words non-stationarity; model bias; drought ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) . Investigating the impact of conceptual model uncertainty and diverging climate change scenarios on groundwater nitrate concentration predictions GERNOT KLAMMLER, HANS KUPFERSBERGER & GERHARD ROCK Joanneum Research Forschungsgesellschaft Graz, Resources – Institute for Water, Energy and Sustainability, Elisabethstraße 18/II, Water Resources Management, A-8010 Graz, Austria [email protected] Abstract At the European scale, nitrate concentration is the most important parameter that determines groundwater quality. Since in most cases nitrate input into the aquifer is a non-point source pollution problem, measures to reduce nitrate leaching have to be designed on the aquifer scale. In this context we have coupled the unsaturated, vertical soil water and nitrogen transport model SIMWASER/STOTRASIM with the saturated groundwater flow and transport model FEFLOW in a sequential manner to simulate groundwater nitrate concentrations for the Westliches Leibnitzer Feld aquifer (45 km²) in southeast Austria. However, in Austria, information about the crops grown is only available as percentages on an aggregated level of cadastral municipalities. Thus, from a conceptual point of view, delineation of the spatial distributions of groundwater recharge and nitrogen leaching time series from arable land are highly uncertain. Within this work, three different approaches consisting of increasing spatial and crop differentiation are employed to investigate the impact on groundwater nitrate concentrations: (i) grain maize production for the entire model area, (ii) one crop rotation per cadastral municipality, and (iii) a stochastic procedure that accounts for the unknown crop grown and applied nitrogen fertilizer amount on each particular lot. Furthermore, the influence of four climate change projections on groundwater, where the predicted temperature and precipitation time series have been statistically downscaled, is investigated. Different combinations of soil water and nitrate leachates are processed as input distributions to saturated groundwater flow and transport modelling. In terms of mean nitrate leaching concentrations, the prediction uncertainty due to the different approaches of spatial and crop differentiation is significantly larger than that due to climate projections. It is shown that even the two climate projections yielding maximum and minimum groundwater recharge and nitrogen leaching do not meaningfully alter the resulting groundwater nitrate concentrations in general. However, at certain locations mean groundwater nitrate concentrations changes are of the order of 20% until 2100. Key words groundwater recharge; nitrate leaching; land-use; coupled modelling; aquifer scale; climate change predictions; groundwater nitrate concentrations ___________________________________________________________________________________________________ 37 Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013 371-376 Subsurface storage in different land use catchments evaluated by deuterium excess KEISHI KUDO1, TAKUTO NAGAMATSU1, JUN SHIMADA1, NAOKI KABEYA2 & NOBUHIRO TANAKA3 1 Graduate school of Science and Technology, Kumamoto University, Japan [email protected] 2 Kyushu Research Center Forestry and Forest Products Research Institute, Japan 3 Life and Environment Department of Kumamoto Prefectural Government, Japan Abstract In order to understand the change of groundwater recharge due to artificial forest plantation, catchment-scale water budget observations were made, including stream discharge, precipitation, evapotranspiration and groundwater level, in the paired forest and grassland catchments of the western foot of Mount Aso, Kyushu, southwest Japan, with conditions of similar geology and surface morphology. The monthly samples of precipitation and stream water discharge from each catchment have been used to analyse the stable isotopes, and those data show clear seasonal fluctuation of the deuterium excess value caused by the change of the source vapour for the local precipitation. The dispersion model, as a flexible transfer function, was used to evaluate the mean transit time of the stream water in both catchments. The results show that subsurface storage in the forest catchment is about 40% larger than that of the grassland catchment despite the similar geology and surface morphology conditions. Key words mean transit time; subsurface storage; vegetation; dispersion model; deuterium excess ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 377-384 . Hydrological responses to combined land-use and climate change in three diverse South African catchments MICHELE L. WARBURTON, ROLAND E. SCHULZE & GRAHAM P. W. JEWITT Centre for Water Resources Research, University of KwaZulu-Natal, South Africa [email protected] Abstract When considering the impacts of environmental change, there is no consensus as to whether land-use change or climate change will be the dominant driver of hydrological response. There is, however, agreement that the effect on hydrological response will be amplified. To understand influences of environmental change on hydrological responses, the ACRU agrohydrological model was used to simulate hydrological responses of three diverse South African catchments under baseline land cover with historical climate and the current land use with downscaled GCM projections of future climate. Consideration was given to the location of key land uses in the catchments and scale issues, from catchment to subcatchment. The impact of environmental change on hydrological responses is complex. The impacts of environmental change on the catchments hydrological response varied across both the temporal and spatial scales, with the nature of the land use and the magnitude of the projected climate change also having significant impacts on the hydrological response. Analysis of the three catchments showed that as each catchment is unique with its own complexities, each catchment will have a unique threshold of where environmental change begins to have a significant influence on the hydrological response. Key words land-use change; climate change; ACRU hydrological model; streamflow responses ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 385-389 . 38 Assessing hydrological impact of land-use measures on peak discharge and total runoff ZAHRA KALANTARI1 & MONA SASSNER2 1 Department of Land and Water Resources, Royal Institute of Technology/ KTH, SE-10044 Stockholm, Sweden [email protected] 2 DHI Sverige AB, SE-111 29, Stockholm, Sweden Abstract Climate change may lead to an increase in the frequency of extreme precipitation events and floods as well as changes in frost/thaw cycles. This will have impacts on the performance and life time of road infrastructures. The frequency of road closures and other incidences will probably increase. The aim of this study is to to evaluate the effect of simulated land-use measures on the local hydrological response changes of a catchment near a low-lying road. The simulated land-use measures in this paper suggest different measures to reduce the generation of storm runoff on site and its delivery to the stream. The effect of these land-use measures on catchment discharge is dependent on the size and time of storm events. Key words extreme events; road infrastructure; hydrological model; runoff; land use ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 390-396 . Modelling runoff response to land-use change using an integrated approach in Xiangjiang River basin, China HONGLIANG XU1,2, CHONG-YU XU1,3, BIN ZHOU4 & V. P. SINGH5 1. Department of Geosciences, University of Oslo, PO Box 1047 Blindern, 0316 Oslo, Norway [email protected] 2 Department of Land Resources and Tourism, Nanjing University, Nanjing, China 3 Department of Hydrology and Water Resources, Wuhan University 4 Department of Chemistry, University of Oslo, Oslo, Norway 5 Department of Civil and Environmental Engineering, Texas A&M University, College Station, Texas, USA Abstract Economic development and urbanization have affected both water quantity and quality in many regions of the world. Understanding and quantifying the hydrological response to urbanization and land-use change have become a major focus in studies of the impact of human activities on hydrology. This study employs an integrated approach that combines the land-use change allocation model (CLUE-s) and a physicallybased distributed hydrological model (SWAT) for examining the impact of various land-use change scenarios in a region undergoing rapid change in land-use – the Xiangjiang River basin in China. Results indicate that various land-use policies have different levels of impact on the simulation of streamflows. Land-use change can lead to significant changes in the distributions of water resources and hydrological processes. Results of this study will be helpful for land-use planning and watershed management. The integrated modeling approach is shown to be a promising tool for land-use impact studies. Key words land-use change; distributed hydrologic model; SWAT; CLUE-s; Xiangjiang River basin ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 397-402 . Hydrological response to land-use changes in a semi-arid region in China XIAOLI YANG1,2, YI LIU1, LILIANG REN1& SHANHU JIANG1 1 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, China 39 [email protected] 2 Civil and Environment Engineering, Princeton University, New Jersey 08544, USA Abstract In recent years, the discharge of the Laohahe River, China, has shown a dramatic decrease and discontinuous streamflow in the rainy season as the result of climate change, human activities, or both. The objective of this work is to document significant runoff hydrology changes induced by land-use change and to quantify the impacts of observed changes on regional hydrologic regimes. Based on the analysis of the characteristics of precipitation and streamflow from 1964 to 2008, statistical methods and the Variable Infiltration Capacity (VIC) hydrological model were used to estimate the effect of land-use change on discharge in Laohahe basin. Firstly, the streamflow of study area was divided into two periods according to the analyses of long-term annual runoff records using the Pettitt test method. Then the hydrological process was simulated by the VIC hydrological model using observed monthly discharge. Furthermore, the simulated results were compared based on land-use scenarios in 1989, 1999, and 2007, respectively. This method is used to explore the effect of land-use changes on the spatio-temporal distribution of runoff in Laohahe basin. The result shows that land-use change has a direct effect on the spatio-temporal distribution of runoff in the study area, while the human activities including water intake and land-use changes appeared to be the most likely factor contributing to the significant reduction in discharge from 1999 to 2008 in the Laohahe basin. Key words hydrological response; land-use change; climate change; human activities ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 403-410 . Télédétection et analyse statistique de la dynamique de la végétation dans un contexte de variabilité climatique sur le bassin versant du Bouregreg (Maroc) ZAMBLE ARMAND TRA BI1, ZUELI KOLI BI2, TELESPHORE YAO BROU3, GIL MAHE4 & ANAS EMRAN5 1 Université d'Artois / Institut de la Recherche pour le Développement / Institut de Géographie Tropicale de l'Université d'Abidjan Cocody, Avenue de l'école de police, 22 BP 940, Abidjan 22 [email protected] 2 Institut de Géographie Tropicale de l'Université d'Abidjan Cocody, Avenue de l'école de police, 22 BP 744 Abidjan 22 3 Institut de la Recherche pour le Développement / Université de le Réunion, 15 rue René Cassin 97715 Saint Denis Message cedex 9 BP 7115, Réunion 4 Institut de la Recherche pour le Développement (IRD) / Université Mohamed V-Agdal Rabat, 15 rue Abou Derr 10000 Agdal-Rabat, BP 8967 Rabat-Agdal, Maroc 5 Institut Scientifique / Université Mohammed V-Agdal Rabat, Avenue Ibn Battouta, BP 703 Rabat-Agdal, Maroc Resume Le bassin versant du Bouregreg appartient aux zones écologiques favorables du plateau central nordouest du Maroc. Ce bassin versant est un espace de céréaliculture pluviale. En outre, ce bassin fait partie des espaces pastoraux favorables du royaume. A l’instar de tout le Maghreb, le pays connaît depuis le milieu des années 70 et le début des années 1980, des conditions pluviométriques de plus en plus aléatoires. Ces variations pluviométriques sont caractérisées par des baisses notables des quantités pluviométriques et une récurrence des épisodes de sécheresse. Cette étude met en lumière la nature de l’évolution spatiotemporelle de la masse végétale dans le bassin de 1980 à 2009, dans ce contexte de crise pluviométrique. A partir de statistiques sur les séries chronologiques constituées des valeurs de NDVI (Normalize Difference Vegetation Index) des pixels des images de la NOAA de 1982 à 2009, l’étude constate une forte régression de la végétation pendant la période estivale. Mais l’analyse de régression entre cette dynamique végétale et la pluviométrie fait ressortir un impact des précipitations sur la végétation pendant les saisons humides, ce qui amène à conclure que des facteurs autres que les précipitations sont responsables de la forte baisse de la végétation en été. Mots clef NDVI; NOAA; test de tendance; bassin versant; pluviométrie; végétation ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 411-417 . Assessing the effect of vegetation change on actual evapotranspiration through a hydrological model 40 YI LIU1, LILIANG REN1, XIAOLI YANG1,2, SHAN HUJIANG1 & MING WEIMA1 1 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, College of Hydrology and Water Resources, Hohai University, Nanjing 210098, China [email protected] 2 Civil and Environment Engineering, Princeton University, New Jersey, USA Abstract Vegetation has a direct effect on the regional evapotranspiration (ET) regime and relevant hydrological processes. Land cover data, classified from original Landsat images of different periods, were used to estimate vegetation change within the Laohahe basin, China. Then, the Variable Infiltration Capacity (VIC) macroscale hydrological model was applied to calculate the corresponding changes in actual evapotranspiration (AET). The VIC model performed well in simulating monthly runoff over the Laohahe basin, with a correlation coefficient, Nash-Sutcliffe efficiency coefficient, and bias of 0.9, 0.88, and 2%, respectively, during the calibration period of 1965–1971, and 0.8, 0.8, and 6%, through the verification period of 1972–1976. The correlation coefficient between annual AET computed by the VIC model and by an empirical equation was up to 0.745. Based on the VIC-simulated annual AET, it is known that vegetation change has exerted an influence on AET both temporally and spatially within the study area. Key words Variable Infiltration Capacity (VIC) model; actual evapotranspiration; vegetation change; Laohahe basin ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013 418-424 Vegetation change and its relationship with precipitation on the southern Tibetan Plateau ZONGXUE XU, WENFEGN LIU, FAPENG LI & PIN LIU College of Water Sciences, Beijing Normal University, Key Laboratory of Water and Sediment Sciences of Ministry of Education, Beijing 100875, China [email protected] Abstract Vegetation on the Tibetan Plateau has experienced significant change during the past decades. Investigation of the relationship between vegetation and precipitation regime plays an important role in the projection of future ecosystem dynamics. In this study, the Mann-Kendall trend detection and Pearson correlation methods are employed to investigate the spatial distribution and long-term tendency of vegetation and its correlation with precipitation by using a monthly dataset of satellite-driven Normalized Difference Vegetation Index (NDVI) spanning a period from 1982 to 2002. Results show that a greenness tendency is significant in the study area, with a magnitude of 0.9 × 10-3 year-1 at a confidence level of 0.01. The trend exhibits different characteristics in different segments and vegetation types along the river. NDVI demonstrates a strong hysteresis effect towards precipitation with the greatest correlation coefficient of 0.55 with 4 months of lag time. Meanwhile, the spatial distribution of correlation shows remarkable variation ranging from –0.54 to 0.67 in the Yarlung Zangbo River basin. Key words vegetation; NDVI; precipitation; Yarlung Zangbo River, China ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) 425-429 . Impacts of climate and land surface changes on urban catchment hydrology _ RANJAN SARUKKALIGE Department of Civil Engineering, Curtin University, GPO Box U1987, Perth, WA6845, Australia [email protected] Abstract Climate change and land-use changes have imposed a significant impact on the hydrological behaviour of catchments. Assessment of hydrological responses to these climate and land surface changes is very important in urban areas. Numerical modelling is one of the best ways to evaluate such hydrological responses against land-use and climate changes. In this study, the XPSWMM urban hydrological model has been used to model an urban catchment in Western Australia, taking its land-use changes and climate variation 41 into account. Impacts of land-use changes on peak runoff of several major and minor rainfall events have been evaluated with reference to present and future land developments in the catchment. It has been identified that land-use change triggered surface roughness changes can increase the post-development peak runoff by up to 10.3% and 15.5% in 1-year and 100-year ARI events, respectively. Changing infiltration parameters due to urban land cover change increased peak runoff by up to 8.8%. The results of the study concluded that the overall runoff generation is more sensitive to land-use change in the catchment. Key words land use; climate change; urban hydrology; catchment __________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) . ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) . ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) . ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) . ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) . ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) . ___________________________________________________________________________________________________ Climate and Land Surface Changes in Hydrology Proceedings of H01, IAHS-IAPSO-IASPEI Assembly, Gothenburg, Sweden, July 2013 (IAHS Publ. 359, 2013) .