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Chapter I INTRODUCTION 1.0 Introduction Morphogenetic parameters such as climate, structure and lithology, resultant drainage, and slope have direct bearing on the choice of natural landuse practices. It becomes thus imperative that the physical limiting parameters must be reckoned with while opting for landuse planning. In many developing countries, the primary landuse determinants have been economic, social and political, whilst the physical determinants have been ignored. It is now increasingly realised that analysis of terrain condition should precede landuse planning . To be more precise, terrain evaluation comprises land classification and creation of a data bank of parametric base taking into account all the genetic factors to meet the practical requirements of any landuse planning. The reliability of information depends on the accuracy of data on different terrain attributes, lithological sequences, natural vegetation, geomorphic and pedologic development (Pathak, 1982). Inversely, sustained landuse practices exert lasting impact on the landform features and often conceal1 modulate manifestations of the dynamic processes taking place in the earth's near surface. Landuse pattern of an area is the outcome of the interrelationship between people living therein and its environment. Apparently static land can be highly mobile through uses. Terrain type and environment determine the landuse pattern of an area, whereas, landuse practices itself, can contribute to the alteration of the landscape having long-term manifestations. Increased human activities, and consequent demand on natural resources especially in the Kerala's context, have resulted in a plethora of changes in landuse mosaic and morphological features, which have caused irreversible alteration to the bio-physical foundation. Many of these alterations could lead to severe environmental degradation and resource depletion, having serious repercussions on State's economy. These changes have generally gone unnoticed or unrecorded. As a result, there are little or no attempts to study thcsc issues in proper perspective capturing all the underlying processes and future consequences. Few studies have been attempted to highlight impact of various landuse practices on the morphogenetic processes. In a State like Kerala, where landscape has been intensely modified to accommodate diverse landuse types within a very limited space and time frame, it is essential to undertake a diagnostic assessment of landuse pattern as a modifier of the geoecological processes. In order to cany out such an in-depth study on the direct impact of geomorphological features on the selection of landuse type, and the latter's impact on the landform, a small river basin in Kollam district of south Kerala, namely the Ittikara river basin, has been selected. 1.1 Conceptual background Geomorphology is the science concemed with the study of the form of the earth. Analysis of landforms, its evolution and change constitute the core elements of the subject. Davisian concept (1899) of "Landform as a function of structure, process and stage" provided the foundation for significant geomorphic enquiry attempting to study the landform from structural, geomorphologic point of view and to understand the erosion cycle. It has been acknowledged, that a complete understanding of the geomorphic processes is necessary for the advancement of our understanding of landforms, although there was little substantive investigation of processes by geomorphologists prior to 1960 (Derbyshire et. al., 1979). The denudative processes taking place on the earth surface is variously affected by climatic factors. Considering the importance of climate in sculpturing the landscape, a branch of investigation of geomorphology commonly known as "climatic geomorphology" has evolved. Process studies, though owes its origin partly to climatic geomorphology, could evolve as a separate approach particularly with introduction of system theory and quantitative analysis. Chorley (1971) identified two distinct lines of investigations in physical geography: (i) process-response systems by the study of contemporary processes, their character as a response to external constraints and their effects and (ii) study of the evolution of landscape and landforms concemed primarily with historical development and chronology. These two distinct lines of investigations are oRen found to overlap and draw from one another. Jennings (1973) identified six approaches in geomorphological research within the realm of physical geography (Table 1.0). Process study figures either as one of the specific lines of enquiry or as a part of climatic geomorphology, and general systems approach. Geomorphic research on processes has gained significant importance over time. A major impetus came from the Geographers of Germany, France, the erstwhile Soviet Union and East European Countries, who attempted process studies as an integrative function of land. The works of BudeI (1977), Tricart and Cailleux (1972), Prokayev (1962), Isanchenko (1973), Richling (1 976) among others bear testimony to the awareness for the need for process studies in geography. Some of these studies also attempted to understand the nature of environmental interrelationships, TABLE I.O APPROACHES IN GEOMORPHOLOGY RESEARCH Approach 1 Denudation chronology Field of study I Elucidation of stages of evolution, study of the Davisian trilogy of structure, process and stage. Climatic geomorphology Recognition of morphogenetic systems, evolving under combination of exogenic processes, varying particularly with climate Morphometry Application of quantitative techniques to define and describe the nature of landforms and their spatial att tern General systems approach 1 Study of process-form relationship adopting concepts from thermo-dynamics Process study of present processes and Quantification understanding processes in physical or chemical terms Structural geomorphology I Study of the influence of type and rock disposition Source: Jennings (1973),Derbyshire et. a/. (1 979). 1 I 1 I I . 1 1 I Morphogenic regions (Fig 1.O) have been identified in relation to rainfall and temperature by Peltier (1950). This scheme of classification applicable in global scale defines morphogenetic region as a region in which a distinctive complex of erosional, transportational and depositional processes is responsible for landform development. The dynamic1 system approach giving emphasis on process measurement and the relation between process and form has been successful in identifying many features of landscape that appear to show consistent relationship between inputs and outputs or form (Renwick, 1992). The equilibrium concept and the idea of positive feedback and thresholds (Langbein and Leopold, 1964; Schumm, 1977, Thomes, 1983) in geomorphology emanated from this emphasis on process studies. MORPHOGENIC REGIONS DOMINANANT PROCESSES I I -10- F -d 6 - O- /" c. 2 t r: +lo- m '. t 0 2 t Mechanical and / Chemical weathering, I running water / mass movement ,/ - ,' +20 - Mechanical running water 0 I I I 2000 1500 1000 I 500 0 Mean annual rainfall (mm) Source: Peltier (1950). Fig. 1.0 MORPHOGENIC REGIONS AND DOMINANT PROCESSES AS RELATED TO MEAN ANNUAL RAINFALL AND TEMPERATURE Morphogenetic processes fashioning the landform from earth materials can be classified as endogenetic and exogenetic. The endogenetic processes are energy forces acting from within the earth's crust and include crusta1 or non-isostatic warping within the mantle, earthquake, folding, faulting, metamorphism etc. The exogenetic processes cover weathering, and surface processes under the influence of climate. The duration, frequency and effectiveness of geomorphic processes record wide distinguishing features in long-time unit that are reflected on landforms. The maturity and chronological sequence of landforms as well as the depositional pattern help reconstruction of climatic changes. However, while analysing the sequence of fluvial or slope deposits, it may be concluded that the deposition represents only a small fragment of time and on the contrary much longer time intervals are reflected in a hiatus or in erosional surfaces (Starkcl, 1977). The present-day geornorphic processes act in smaller time frame, following the seasons of the year, especially the annual sequence of water circulation. The tropics, characterised by heavy seasonal rainfall and high temperature experience fluctuation in water and sediment production and movement due to monsoonal effect. The seasonal factor data can be used in classifying geornorphic process (Wilson, 1973). There are two group of processes in an annual cycle- the secular and the episodic group of processes. The secular processes are characterised by low intensity and long duration, and the episodic processes are of very low frequency and act only during several days or even hours in a year. Among the secular processes, it is possible to distinguish continuous processes such as chemical denudation (solution) going on in soil throughout the year and seasonal or periodic processes such as slope wash, cryogenic processes or transport of the suspended load in rivers (Starkel, 1985). Whether the process is of short-time annual duration or of long-time duration, the modifying factors over the climatic parameters are the vegetation types or more particularly cover types. Vegetation is considered to be an indirect impact of climate. In a given climatic environment the plant cover modifies the morphogenetic processes, but, in turn the latter influence the ecologic conditions (habitat) and thus have repercussions on the vegetation (Tricart and Cailleux, 1972). The plant formation types interpose a screen of variable importance between the agents of the weather and the lithosphere. Depending on the density of undergrowth, vegetation plays an important role as filtering mechanism. It has to be taken note of that it is seldom the climatic factors of precipitation and temperature alone which determine the morphological forms. Important morphological changes may take place through alterations in the vegetation which are instigated by human activities rather than climatic condition (Zonneveld, 1975). Given the complex interrelationships of geology, climate, plant, landform and soil in activating morphogenetic processes, it is quite natural that the concept of scale has to be addressed while considering the interaction of various morphogenetic factors. Morphogenetic processes are greatly influenced by plant formation types on a world scale or macro scale. On a regional scale there is an interplay of pedologic, palaeoclimatic and biogeographic influences on the morphogenetic processes and, anthropogenic activities are the most important universal modifier of morphogenetic processes. Further down in a local scale, the plant species/ vegetation types are the indicators of morphogenetic processes. In addition there is an interaction between morphogenic and pedogenic processes at the site level. Identification of top0 sequence and its relation to soil catena forms an important research problem in soil geography. Spatial variability of geomorphic processes encountered on earth surface has led to enquiries that seek identification of homogenous units. However, homogeneity itself needs to be defined in terms of the amount of variability accommodated within such unit (Caine, 1982) and the type and number of criteria considered. Land, as defined by Mabbutt (1968) "is a complex of surface and near surface attributes significant to man" and Gardiner (1976) stated that "land refers to all those physical and biological characteristics of the land surface which affect the possibility of landuse". Most of the land classification systems taking a broader view attempt to encompass all environmental components, whether or not they are relevant directly or indirectly to man's use of the land. Moss (1983) proposed a land classification scheme by incorporating process data (Fig. 1.I). It begins with energy and moisture input and finally provides the basis and scope for even mathematical modelling. This model provides conceptual clarity and theoretical background for incorporating process data into the scheme of land classification. This theoretical framework could be interlinked with biophysical land classification proposed by Moss (1975) for Canada, Land System approach of CSIRO, Australia and Terrain System of ITC, The Netherlands. The units identified under different morphogenetic processes can be ordered into a hierarchy and use of data at each level could be indicated (Table 1.1). Human induced changes are reflected in the landuse pattern of any given area. (1) ENVIRON INPUI'S: MAJOR CONTROLS (3 INTEGRATING LANDSCAPE IJNITS (2) CONTROL PROCESSES (4) (5) LAND UNIT COMPONENTS (6) BASIS AND NATURE OF DETERMINATION PROCESS RESPONSE - ENERGY BIOTIC WATER MOISTURE BUEGET 1 VEGETATION AND 1 1 PEDOLOGIC HYDROLOGIC L PRIMARY PRODUCITIVITY MATHEMATICAL MODEL DECAY AND DECOMPOSITION MATHEMATICAL MODEL SOIL MOISTURE FLOW OF NUTKI EN'I'S 1 CAI .CUI.ATIONS SURFACE RUN-OFF Source: Moss (1 983). Fig. 1.1 A MODEL TO ILLUSTRATE A METHODOLOGY FOR THE INCORPORATION OF PROCESS DATA INTO LAND CLASSIFICATION TABLE I.ITERRAIN SYSTEM, PROCESS DATA AND APPLICABILITY Level of hierarchy Terrain province1 eco-region Scale Process data >1:250,000 Natural vegetation1 Biomass Terrain pattern1 Terrain system 1:250,000 Pedological processes Terrain unit/ Land unit/ Ecosection Terrain components1 Ecosite 1:50,000 Geomorphicl hydrologic processes Natural changes and impacts due to human intervention (anthropogenic processes) 1:10,000 Environmental value of data Land surface dynamics (fundamental land1 biotic function controls) Modificationofbasic functions by local controls (soil capability) Local expression of changes in controls by various processes Site specific information processresponse Use of data Major regional decisions concerning land management Rankingof potential value for regional decisions, geo-ecological evaluation Landuse planning Soil erosion potentiall critical area assessment 1 Due to interlinkage of rnorphogenetic processes, the hnctional changes in humanenvironment relationship reflected through landuse pattern trigger a cascading change from local to global levels, from specific to diffuse and from low complexity to high complexity. Landuse change takes place at the site level or micro level, whereas, drivers of landuse change can be either proximate cause or macro level decision or both and similar is the case with impact of landuse change. The horizontal and vertical linkages of landuse change, especially in the case of deforestation is given in Fig. 1.2. Environment Economic Sociat Source: Gallop in (1994); Winograd (199 7). Fig. 1.2 VERTICAL AND HORIZONTAL LINKAGES: THE CASE OF LANDUSE The morphogenetic processes are thus subjected to alteration as a result of landuse change. Capturing of these changes and study of their impact on landscape form important research agenda. Many of the landscape studies attempt to concentrate on interaction of the ecological processes with the environment to create landscape pattem and influence of these patterns on ecological functions (0 Neillet. al., 1995). There is a need to develop measures of spatial pattern and to correlate pattem with ecological processes in micro level study, particularly in today's context of societal quest for sustainable development. The present thesis is based on the above conceptual framework. The morphogenetic processes have been-linked to landuse pattern and geoecological impacts were assessed. The study framework is given in Fig. 1.3. , Analysis /-+ Evaluation Landuse Morphogenetic processes + Geology + Climate + Hydrology Agricultural and other use Change + Landfonn + Soil + Vegetation I \ Environmental evaluation Deforestation Soil degradation Jr Sand and clay mining * *Jr Demography * Occupation Geoecological impact +3 Landform and landuse Q Landuse, water quality and hydrogeochemistry +3 Landuse and demography 4 I Load I I Impact 1 Fig. I.3 STUDY FRAMEWORK 1.2 Review of literature Study of rnorphogenetic processes had gained importance during the 2ndhalf of the last century. Although, the necessity for the study of processes has been felt since the development of the subject, substantive research activities related to processes could be traced since 1950s (Chorley, Dunn and Beckinsale, 1964, 1973). As early as 1877 Gilbert wrote about the erosion, weathering, transport, deposition and equilibrium in studying the geology of Henry Mountain, Utah. Various approaches followed in geomorphology have been reviewed by Chorley and Kennedy (1971), Dury (1972), Jennings (1 973), Brown (1975) and Chorley (1978). All these reviews tried to highlight the development of the subject and the main thrust. Development of theory of geomorphology has been ' envisaged through a number of phases from teleological to taxonomic to functional (Chorley, 1978). Derbyshire et. al. (1979) attempted to provide an introduction to geomorphological processes and their operation procedure. Process studies have progressed in four ways (Selby, 1985): These are: (i) detailed measurements both in the field and laboratory based firmly on physical sciences, (ii) use of statistical techniques and rigorous measurement, (iii) availability of large volume of data and computer application and (iv) enlarged scope of work due to availability of fund and trained manpower. Recent improvement of knowledge covering the aspects of rate, mechanism, models and application has added impetus to geomorphic research related to processes. German and French geomorphologists had drawn attention in incorporating climatic variables in geomorphic studies. The branch of climatic geomorphology has been evolved in these processes. Budel (1977) contented that exogenous processes, in their climatic variation, create the morphological picture of the earth, while geological structures and tectonics merely influence and modify local landform (Selby, 1985). Identification of morphogenetic regions associated with dominant processes and climatic variables was attempted way back in 1950 by Peltier (1950) in a global scale. This approach could not take note of the periodicity of geomorphic processes in relation to climatic seasonality, role of vegetation and soil and impact of anthropogenic intervention in modifying the landcover. However, subsequent developments in climatic geomorphology have tried to address the role of vegetation and soil. Climatic geomorphology indeed must examine the interactions between all the factors influencing the processes covering geologic structure, climate with seasonal variability, vegetation and soil (Tricart and Cailleux, 1972). Geographers of Soviet Union and other East European Countries have contributed significantly in furthering process studies in geography. Works of Isachenko (1 973), Prokayev (1962), Starkel (1 976), among others, are noteworthy. Study of landscape evolution depends on understanding the present spatial distribution of processes and process rate, linkage between erosional and depositional component, comparison of spatial versus temporal change and appraisal of stratigraphic record. The Binghamton symposia concentrated on "Space and Time in Geomorphology" to cover these issues (Thorn et. al, 1982). Significance of the process studies, as Johnson (19 82) pointed out is "in understanding the mechanics and control of geomorphic processes and short-term variability and behaviour of geomorphic systems and land forms". Response of the processes can be captured spatially by identifying different landform or terrain units. Since Mabbutt's (1968) and Gardiner's (1976) emphasis on land as an end product of complex ecological interactions, there have been various approaches proposed from time to time. Moss (1981, 1983) proposed land classification methods by incorporating process data. The Land System approach by CSIRO, Australia and the Terrain System approach by ITC, The Netherlands attempted to classify land following landscape approach incorporating geomorphic processes (Meijerink, 1988, Chattopadhyay and Mahamaya, 1995). As process study is related to dynamic/ system approach, it is necessary to investigate within a framework of a river basin, which collect, concentrate and coordinate the movement of water and sediment. Gregory (1976) reviewed the drainage basin studies since 1700 and identified seven approaches: Morphometry (spatial and topology), Basin characteristics, Channel pattern, Channel geometry, Theory, Dynamics and Palaeo studies. From Horton's (1945) morphometric analysis to Chorley (1962), Schumm's (1 977) emphasis on palaeohydrology and metamorphosis of rivers and river channels, the primary concern is to understand the process variation in water and sediment production over time and effect of processes over landforms at present, in the past and also in the future. Recent attention has been drawn to the applied studies. During 1970s greater emphasis was given for a more integrated approach to environmental problems and in subsequent three decades research agenda changed at various levels. Environmental impact assessment, sustainability and sustainable development become part of the common usage not only in research parlance but also in general society. Spatial heterogeneity and pattern observed in the field are recognised as important landscape components and not averaged across the space. Site-specific intervention of human being on the terrestrial biosphere creates a mosaic of Landuses that tend to threaten the basic mosaic of the intact ecosystems on intact landscapes (0 Neill, et. a[., 1995). In a review article Stuart Chapin et. al. (2000) observed that "landuse change is projected to have the largest global impact on biodiversity by the year 2100 followed by climate change, nitrogen deposition, species introduction and changing concentration of atmospheric COz". Studies on landuse and landuse changes are not only gaining more and more importance but also becoming the focus of mu1ti-disciplinary studies covering a host of issues related to drivers as well as consequence of change. Turner (1999) proposed merger of local and regional analyses of landuse changes because regional and local processes are highly interconnected. Butte1 and Taylor (1994) made similar observations in their studies on environmental sociology and global environmental change. Walker and Solecki (1999) pointed out that land conversion (local issue) often becomes a serious environmental issue at the regional scale involving regional ecosystems. Blakie (1989) highlighted the relation between land degradation and landuse at the local level. He pointed out the emphasis in the classic approach on environmental problems leading to environmental solution and on the 'ignorance' of land users. Several studies on landuse have been attempted in India at different levels. Most of the works were initiated following Dudly Stamp's landuse survey of U.K. in the beginning of 1940s. It was at the 1940 session of the Indian Science Congress held at Madras that Prof. S.P.Chatterjee pointed out the necessity of undertaking the landuse survey in Tndia on the lines of the landuse survey of Great Bretain. He published a report on "Land utilization in the District of 24 Parganas, Bengal" in 1945. Dayal (1947) prepared a thesis on agricultural geography of Bihar. He discussed the influence of soils and climatic elements on land utilization, the pressure of population on land and the nature of land utilization. Chattejee (1952) undertook more detailed land utilization survey in Howrah district and 1200 landuse maps at the scale of 1:3960 covering 813 villages were prepared. Rao (1947) has emphasized the techniques of soil survey for analysis of landuse in the Godavari region. Roy (1968) documented rural landuse pattem in Azamgarh. Singh (1971) dealt with the optimum carrying capacity of the land in Punjab. Deshmukh (1 975) studied rural landuse of Lonkhede. Models in land utilization were documented by Mandal(1980). Sustainable development initiative was documented by Singh (1996). Planning for sustainability on natural resources and bio-energy was attempted by Maheshwari et, al. (1996). There had been a change in landuse studies in India, from mere documentation of changes the attempt is now to investigate the cause and consequences of landuse change. Advent of Remote Sensing and Geographic Information System (GIs) have facilitated time-series and multi-variable analysis. Chattopadhyay (19 85) studied deforestation in Keral a and attempted to highlight the related issues. George and Chattopadhyay (2001) analysed the landuse in Kerala in relation to population pressure. Biophysical land classification for the State of Kerala was attempted by Chattopadhyay and Mahamaya (1998) in order to design sustainable landuse pattem. Maharnaya (1998) attempted geomorphic analysis for sustainable landuse development in a small drainage basin of south Kerala. The thrust of the paper was to link potential landuse with land units identified based on processes. River basins are considered as natural integrators of the effects of many natural and anthropogenic inputs and anthropogenic interventions. Water quality parameters are determined and hydrogeochemical investigations of rivers, water bodies and oceans have become important tools to evaluate the environmental degradation of catchments for identification of sources of pollution. Major scientific concern about global river quality dates back from the 1950's when the International Association for Scientific Hydrology launched a world-wide programme for the first time (Durum, et. nl., 1960). This work was one of the databases of Livingstone (1963), a master-work on river chemistry which still constitutes the only available thesaurus at global scale. Meybeck and Helrner (1989) did the monitoring of river quality of pristine stage to global pollution. Meybeck (1998) studied man and river interface, its multiple impacts on the Seine river basin. Biogeochemistry of major African rivers was documented by Martin and Probst (1991). Further, Meybeck (2001 ) worked on global alteration of riverine geochemistry through anthropogenic interventions. In India, Agarwal and his team (1976) assessed water quality parameters (physico-chemical) of the Ganges at Varanasi. Chandrasekhara Chetty (1978) documented utility aspects of river waters affected by saline incursion in Goa. Subramanian (1979) generated hydrogeochemical data sets for the major drainage basins of India. Varshney (1981) worked on water pollution and management reviews, Trivedi (1988) generated data sets on ecology and pollution of Indian rivers. Venkateswarlu and Sarnpathkurnar (1982) made chemical and biological assessment of pollution in river Moosi, Hyderabad. Systematic hydrogeochemical investigations have been initiated in Kerala with the pioneering work on Killi Ar (river) (CESS Report, 1995, 1996). Mahamaya el. al. (1996, 1997) documented results and generated data on Killi Ar (river). Human impact on the biogeochemistry of rives has been studied by Ittekkot and Subramanian (1999). Dekhov et. al., 1999 has documented chemical composition of riverine suspended matter and sediments from the Indian sub-continent. Suresh (1999) has studied impact of urbanisation on quality of groundwater regime. Status of riverine pollution in south Kerala and its relation to physiography and landuse have been documented by Soman, et. al. (1997,2002). This brief general review of literature has brought out that there were several topical studies attempted at di fferent levels but few studies tried to link rnorphogenic processes with landuse within a larger fiame of analysis, evaluation and impact studies. 1.3 Objectives The study on Ittikara river basin has been undertaken with the following precise objectives: a. In-depth analysis of the morphogenetic processes operative in the Ittikara basin including elucidation of the role of geology and structure on landforms, morphometric analysis of surface drainage, landform analysis covering slope form and profile analysis, and finally identification of morphogenetic regions, b. Detailed analysis of the landuse pattem and its changing trend over the years, c. Assessment of human resources and importance of demographic parameters in altering physical processes, d. Evaluation of major environmental issues, especially problems of deforestation, soil degradation, sand and clay mining as contributors to changes in riverine ecology, and analysis of hydrogeochemistry and environmental biogeochemistry as indicators of water quality and onland changes, e. Impact assessment of morphogenetic processes on landuse pattem and 1 'ce versa, impact analysis of landuse pattern on water quality, interrelation of landuse pattern and demography, and f. Application of Geographic Information System (GIs) for understanding the geoecological impact. 1.4 Study area The Ittikara drainage basin occupies the southern sector of Kollam and a small portion of Thiruvananthapuram districts and it extends from 8" 44 10 N to 9' 0 50 latitudes and 76" 37 E to 77' 2 20 E longitudesl'he river Ittikara originates from the low hills of Karakumu (250 metre above Mean Sea Level) adjacent to Madathara in the foothill region of the Westcm Ghats and flows through the Yeroor Reserved Forest area in a straight north-westerly course where streams of various orders are formed and join the main river (Fig. 1-4). After flowing over the midland terrain river Tttikara debouches N LOCATION MAP IlTlKARA DRAINAGE BASIN - 5- D I INDEX Roed cr--H ------- k b l d bwndary Fig. 1.4 I Railway I W - Stream I I into the Paravur Kayal north of Paravur in the south-western portion of Kollam district (Fig. 1.5). The river Ittikara is a west-flowing stream. The river has a length of 56 km out of which 16 km stretch is considered for navigation in the downstream section. Catchment area of the basin is 650 km2. The length of :he coastline forming the western boundary of the study area is 9.50 lan.The basin comes under the realm of tropical drywet climate. Ittikara basin encompasses 7 blocks covering 32 panchayats and one municipality (Fig. 1.6). Before discussing characteristics of the study area surface and groundwater conditions are discussed here briefly in order to provide the background information. The total surface water potential in the Ittikara basin has been computed to be 446 MCM (CGWB, 1987). Monthly discharge varies from 1972 to 1992 (Appendix I). Around 7.1% of the annual rainfall drains out as base flow in the basin, however, it records spatial variation depending on terrain type, soil, landuse and management practices. Base flow contribution derived from data obtained fiom Ayur gauging station for the period of 1972 to 1992 is determined to be 14.5% of the annual run-off. The annual percentages of base flow varied between 2.7% and 19.9% of the annual run-off. With the available limited data, water table contour map has been prepared for Ittikara basin (Fig. 1.7). It was based on water-level measurements in the wells for the pre-monsoon, 1994. Contours could not be drawn in the upland portion of the basin due to non-availability of data. Water table of the basin is controlled by its physiography, geological formations, extent of weathering of rocks, rainfall and vegetation cover. Water table contour pattern tends to follow the contours of the overlying ground surface, although in a more subdued form. Water table contour map shows that the general flow o f groundwater is towards west. Geologic and geomorphic setting and structural features of the area under normal conditions of precipitation control the occurrence and movement of groundwater. Continuity, thickness and aquifer characteristics of the strata determine the groundwater storage potential (CESS Report, 2001). In order to assess the groundwater potential of the Ittikara basin hydrogeology map was prepared (Fig. 1.8). Along with lithologic features, DRA l NAGE ITTIKARA BASIN I Fig. 1 . 5 I I ADMINISTRATIVE MAP ITTIKARA DRAINAGE BASIN 1 -0 I 2 h Legend O D i s l r i c l Boundary Block Bol~ndary Panohayat Boundary Road Rnl lway WATER TABLE CONTOUR ITlKARA DRAINAGE BASIN D -10- Contour (m) (above MSL) NA Dala not available 5Kms Sourn: year 1994. R-onn HYDROGEOLOGY IlTlKARA DRAINAGE BASIN 0 urkm.~ Lateli. m Gama - blots. Khondallte Fig.1.8 Ple~~t~cene gneiss h INTRUSIVES AGE Recant 5 # - SIhb and d ~ p d]olnI --._ . . M~owne -+ C Archasan t ---. + Area suhble for grnund water dmloprnenl wilh a thick zone of latent0 Imlley fill Major fault zone Araa s u W c Lor groundmter ~ a b w w l b p o ~ Alarmn Ummant Gatrce CGWB 1087 structural and terrain details were also considered for evaluating the water resource potential. Areal spread of lithological units show that hard crystalline rocks comprising khondalites, garnet-biotite gneisses and the intrusives occupy about 45% of the study area. Groundwater potential in this zone is relatively low. Towards west, rolling terrain with laterite formation has better groundwater potential. Coastal sedimentary beds show good groundwater prospect. The Ittikara basin displays unique physical diversity ranging from wide coastal plain and low-lying lands in the west to dissected midland and highlands of the Western Ghats in the east. The major landuse category in the basin is settlement with mixed tree crops. Recent landuse survey reveals that a considerable portion of the area under mixed tree crops and forest are converted into rubber and plantation crops. The water resource of the basin is assessed as 429 ~ r n The ~ .wetlands of the basin, according to the PWD (1974) estimate require 343 ~ r n of ) water for imgating three paddy crops and 50% of gardenlands need 123 ~ r ofn water. ~ At present, no major irrigation scheme is in operation. However, the Kallada Irrigation Project is supposed to imgate an area of 152 km2 of the basin. Irrigation facilities are provided by a few lift and minor imgation schemes at present. Detailed investigations are being carried out for the Ittikara River Valley scheme for examining the scope for irrigating the lands to the right bank of the Ittikara river which are not covered by the Kallada Project and those to the right bank of the Varnanapuram river. In addition to these, there lies the scope for construction of a number of subsidiary storage across the river in its upper reaches. Eravipuram panchayat of Mukhathala block recorded the highest population density of 5533 personsflanL whereas Kulathupuzha panchayat of Anchal block had a population density of 78 persons/krn2 according to 1991 census. The basin area has well connected road networks. According to the Department of Economics and Statistics, 1996, the National Highway has 25 km, coverage within two panchayats and 66 km of State Highway falls within seven blocks encompassing the study area (Appendix 2). Other than these, Main District Roads (MDR) owned by FWD, Kerala and panchayat roads are also well maintained. 1.5 Methodology and data source In order to pursue the study proposed here, qualitative and quantitative analyses of a large number of parameters covering biophysical, landuse, and demographic characteristics are envisaged. The methodology will address the issues related to morphogenesis and interrelated aspects like terrain pattern, geoecology and environmental evaluation. An effort has been made to establish causal relationship among apparently independent factors. Methodology adopted included primary data collection, field mapping, map analysis in laboratory with the help of topographic sheets of 1:250,000and 1:50,000 scales, secondary data collection from various departments and computer application in data assimilation and display. Analyses of physical factors and landuse mapping on macro scale as well as in micro scale have been taken up. Analysis and mapping have been done for the Ittikara basin as a whole and for its three important sub-basins, eg. Palliman Ar., Kulanji Thodu (stream) and Man Ar which are situated on three different physiographic units. Geographic Information System (GIs) are a useful and perhaps necessary tool for incorporating environmental indicators into the development process. As the data really represents actual-ground condition and can be transformed and manipulated interactively in a GIs, they can serve as a test bed for understanding the environmental processes or for analysing the results or trends or for anticipating the possible results of planning decision (Burrough, 1986). The geological map has been prepared by assimilating data from existing geological maps. The lineament map was prepared by deciphering data from IRS image in 1:50,000 scale. Morp hometric analyses or quantitative geomorphology of drainage basins and channel networks were taken up to understand river geometry. This section treats quantitative landform analysis as it applies to normally developed watersheds in which running water and associated mass gravity movements, acting over long period of time, are the chief agents in developing surface geometry. Emphasis is upon the geometry itself, rather than upon the dynamic processes of erosion and transportation which shape the forms (Strahler, 1964). Linear aspects of the channel system, areal aspects of drainage basin and relief aspect of drainage basin have been attempted in order to appraise the channel morphometry and to understand the denudational processes operative in various parts of the basin. In evaluating terrain, the classification system must begin with the "main origin", the dominant process currently operative. Under each of these dominant processes or specific origin a number of sub-units have been identified which has formed the base of morphogenetic regions. Geomorphological mapping has been done based on identification of terrain units by landscape approach propagated by International Institute for Aerospace Survey and Earth Sciences (ITC), the Netherlands (Verstappen and Van Zuidam, 1968) and as adopted for Kerala by Chattopadhyay and Mahamaya (1995). It was based on experience in the use of the then known geomorphologic systems and legends used for map-making of various parts of the world. The ITC methods were modified and developed further and it became a true mapping system with distinct characteristics. Three main approaches can be recognized which have been considered in designing such a system; these are: 1. the genetic approach 2. the landscape approach 3. the parametric approach In the genetic approach, much attention is given to geologic aspects and geomorphologic processes, with little attention to landforms. The landscape approach can be further modified if it is based on landform, lithology and genesis. The landform characterises the landscape quite well. They are recognized with ease both in the field as well as from image and can easily be grouped into systems or sub-divided into components. Another advantage of this approach is that the units can be grouped into higher order or can be sub-divided into lower order depending upon the number of variables considered. The parametric approach refers to the terrain classification on the basis of selected attributes like slope, altitude etc. It provides a quantitative fiamework for an otherwise qualitative or descriptive map. Table 1.2 modified and adopted from Babiker (1 977) provides a comparative statement of important characteristics of different approaches: TABLE I.2 TERRAIN CLASSIFICATION APPROACHES I Genetic approach I Landscape approach I Parametric approach I I Characteristics Reconnaissance survey Possible Possible Difficult Semi-detailed Not Applicable Possible Possible Unit dimension Large Units Medium to small size Small Boundary Vague Clear Vague Homogeneity of units Not possible Possible Field identification of units Possible in terms of single parameter Difficult Easy Limited, mainly academic Planning Oriented Short Short survey Time duration for Difficult Limited Long survey Although, there are differences among these approaches, it is important to consider them as complimentary. A combined approach provides significant results particularly where the purpose is application oriented. It is possible to consider genetic data, landform attributes and specific parametric data for the units depending upon the need or planning requirement. It is possible to establish hierarchical classification system for terrain analysis by involving more and more parameters at different levels. The classification process begins with geomorphologic origin followed by specific origin, lithology, morphometry (relief, valley density, slope form) and finally incorporating soillcatena information, sequence can be established. Table 1.3 is compiled to show the hierarchical classification system followed in various countr~eslinstitutions. It is evident from this Table 1.3 that there is a similarity of thought about the occurrence of identifiable units of landscape, which can be arranged into a hierarchical order. TABLE 1.3 HIERARCHICAL CLASSIFICATION SYSTEM Level I II Scale CSlRO Australia Bio-physical (Canada) I:250,000 Terrain Province/ Complex land system Eco areal Eco region Land Terrain pattern/ Land Eco zone Ecodistrict 1:250,000 Oxford MEXE Physio graphic ITC (Netherlands) Germany Soviet Union Physiographic province Terrain Province Macrochore Landscape mestnest Land System Main physiographic unit Terrain system (pattern) Mesochore Urochische Eco section Land facet Detailed physio graphic unit Terrain Unit Microchore Urochischa Ecosite Land element Physio graphic element Terrain component Eco-tope complex Facies region system III I : 50,000 Terrain unitlland unit IV 1 :I 0,000 Terrain componentlsite - The terrain classif cation scheme adopted for Ittikara basin is landscape approach based on a scale of 1:50,000 and incorporates data related to all aspects of morphologic processes, rnorphometry, soil and landuse. This scheme partly draws from the ITC system of geornorphologic mapping. The classification scheme adopted here follows the principle of hierarchy theory (Haigh, 1987). A 4-order classification system has been built-up (Fig. 1.9). Each order is so defined that the units are mutually exclusive with a specific generic concepts and a lower order unit represents a sub-order of the immediate higher order unit. The higher order units (1'' and 2" order) have been identified using the . terrain units have been existing body of knowledge. The 3" order categories, i . ~ the demarcated from the landsat data products, whereas the 4th order categories were identified from PAN image analysis and through field mapping. ' ATTRIBUTE LEVEL SAMPLE TYPE Terrain province level-1 Western Ghats1 Upland 1 I Climate 1 ~rocess-1 r Physiography Lithology I I Terrain system level-ll Structure Accretionall Erosional units Erosional state - i Landform Morphograp hy -- h Terrain component Floodplain1 level-Ill Beach - Geoforrn I Terrain component level-IV Valley floor1 Levee Fig. 1.9 THE SCHEME OF TERRAIN CLASSIFICATION Mapping has been done in 1 :50,000 scale by using topographical maps and in 1:25,000 scale extracting data from PAN image (IRS IC, 1999) for selected sub-basins. Slope maps of selected three sub-basins of Ittikara Ar have been prepared by dividing the area in 0.25 km2 grid and computing the average slope for each grid by taking into account the lowest and the highest altitude and distance between these two points within the concerned grid (Chattopadhyay and Mahamaya, 1995). The importance of hydrology in the assessment, development, utilisation and management of the water resources of 'any region is being increasingly realised at all levels (Raghunath, 1985). Rainfall data analyses have been done with the available data. The river is being gauged at Ayur and Ittikara. However, the available discharge data are not suficient for any correlation study. Hydrogeological map has been prepared along with the water table contour map. Well depths were monitored for this purpose with supplementary data obtained from the Central Ground Water Board. Landuse bears a close correspondence with the terrain characteristics, especially in the tropical countries, where agriculture is much akin to the natural ecosystem (Mahamaya and Sakunthala, 1987). The study envisages to characterize landuse units in relation to land system units and in turn to assess the land potential for better management. Landuse map for the Ittikara basin has been prepared in 1:50,000 scale using topographical maps and IRS image. Three sub-basins of Ittikara river covering 48 % of the basinal area have been taken up for detailed analysis. Data have been extracted from PAN image (IRS IC, 1999). The principle of visual interpretation of satellite image is followed. As a first step image characteristics are translated into land management attributes. The translation process (transfer function) is guided by local knowledge (eg. soil, geologic or landuse maps; reports or agricultural statistics), which can be gathered during fieldwork or through background studies. In the next step polygons are drawn around features (fields, land units, homogeneous areas with natural vegetation, settlement etc.) and a label referenced to tables is assigned to each polygon characterizing it by attributes (the legend). Image characteristics can be pattern, texture; colours or tones on the image; or the changing colour during a growing season (Bronsveld et. al., 1994). These were subjected to detailed field verifications. Time-series landuse maps were prepared to detect changes oveL the years. Accurate up-to-date information is of critical importance for land management. Data on changing conditions are needed continually to detect problems, plan activities and predict and monitor results of activities. Agriculture is the prime occupation of the people of this basin. Crop statistics for the period of 1996 for Kollam and Thiruvananthapuram districts were collected from the State Planning Board, Government of Kerala, Thiruvananthapuram. Crop combination method proposed by Weaver (1954) has been used to indicate dominance of crop practices at panchayat level. The details of the method are given in Appendix 3. Analyses of demographic parameters were based primarily on 1991 census data. Decadal growth of population, and population density have been calculated for each panchayat. Occupational structure of the populace has been dealt with. The chapter on environmental evaluation is based mainly on primary data and observations. Secondary data were also used to supplement the findings. Extent and depletion of forest coverage have been marked from satellite image of 1999. Estimate on sand and clay mining were based on primary data. Hydrogeochemical analysis and study on environmental biogeochemistry were conducted through primary s w e y . 17 sampling stations were selected based on a combination of physiography, drainage and landuse parameters. Water samples were collected and they were analysed for physico-chemical and microbiological parameters in the Chemical laboratory of the Centre for Earth Science Studies. Biogeochemical samples were analysed at the Institute of Biogeochemistry and Marine Chemistry, University of Hamburg and at the Center for Tropical Marine Ecology (ZMT), Bremen, Germany. Geoecological impact assessment aims at identifying the consequences for the biogeophysical environment and for man's health and welfare of implementing particular activities (Michele et. nl., 1995). Geographic Information System (GIs) is a useful and perhaps necessary tool for incorporating environmental indicators into the developmental process. The integration of economic, social and environmental indicators in a spatial framework allow for more powerful and realistic analyses than those offered by conventional non-spatial methods (Wingrad and Eade, 1997). GIs based overlay analysis and modelling are extremely useful for aiding our understanding of environmental systems and helping in management decision making. Integration of data on landform, landuse and water quality was possible through application of GIs. Thematic maps on landform, landuse, relief, drainage, drainage density, population density along with their attributes were integrated using PC ARC/INFO and PC TIN softwares. 3-D modelling was accomplished from the 20 m-interval contour map of the study area (part). This is a representation of a surface derived from irregularly spaced sample points and break line features. Each sample point has an X, Y coordinate and a surface of Z value. These points are connected by edges to form a set of non-overlapping triangles that can be used to model the surface (PC ARCtINFO, 1995). Thus digital terrain model (DTM) for a subbasin has been created by regular array of Z value, referenced to a common datum which represents terrain relief. Overlay analysis is also done to ascertain the interconnectivity. Spatial and seasonal variations of DO, BOD and FC are shown through G I s analysis. The sampling stations along the main and tributary streams were digitized. DO values for different sampling seasons were marked by attributing class interval and linear influence of the sampling stations as emerged from the analytical results (CESS Report, 1996). Product moment correlation coefficient has been worked out based on the indices value calculated for each panchayat in order to understand the spatial association and intercorrelations among population, landuse and gross cropped area of panchayats. 1.6 Hypothesis Following hypotheses related to objectives for the study on Ittikara river basin have been cited. An attempt has been taken to establish the hypotheses regarding morphogenesis and landuse and vice versa, in the following chapters. The hypotheses are as follows: * Terrain condition is a determinant of landuse pattern Landuse pattem is primarily governed by the terrain condition. The physiography-soilmatrix exerts pronounced influence on landuse pattern as is explicit in the State of Kerala. It is intended to test this observation under this hypothesis. * Landuse/landcover alterations impact landscape type Landscape types are modified by landusel landcover changes. When wetlands are diverted to garden lands and to accommodate settlement, the local slope condition, surface run-off and infiltration rate etc are modified. This hypothesis attempts to highlight this issue. * Spatial variations in landuse pattern influences water quality Drainage discharges, both quality and quantities are influenced by rainfall, terrain type, soil, geology and landuselland cover. Given a uniform rainfall pattern soil, ten-ain and geologic condition, it is the landusel landcover that affects the drainage discharge pattern. It is necessary to study the spatial variability of landuse and water quality parameters to capture this impact. This hypothesis is designed to test this interrelationship. * Landuse and landscape alterations affect biogeochemical cycling. Alterations of landuse and landscape, although occur locally, have long- range impact on biogeochemical cycles as they affect the water system through which the cycles are linked. This hypothesis will posit the study in a larger fi-ame. 1.7 Expected contribution of the thesis This thesis is expected to contribute in understanding the overall environmental condition of the basin especifically in the realm of the following five issues: 1) deciphering the responses of natural systems to environmental changes; especially in the realm of landusel landcover changes and their responses on the landscape as well in the aquatic system, 2) integration of environmental parameters into landuse planning and management, 3) geoecological impact assessment of activities that can affect land-water systems through RS-GIs application, 4) definition and listing of indicators that can be used to assess different impacts, and 5) design of remedial actions. Geomorphologic indicators, measured successively over time, are expected to describe trends in the conditions of phenomena, systems, resources or assets. Goemorphologic indices can help in assessing the impact of human activities, for example on sediment transport and erosion processes, and the degree to which these processes interfere with human activities (Rix,1995). Reconsideration of earth science education was proposed by Fabbri and Cendrero (1995) in view of research contribution in problem identification and problem solving. In this context the present thesis will have a long-term contribution. As the framework of this thesis is multi-disciplinary, it is expected to enrich the roots of Earth Science education. , 1.8 Arrangement/ Organisation of the thesis The integrated structure of the many different components in the complex array of morphogenetic analysis and its impact on landuse pattem as well as geoecological assessment make it difficult to compartmentalize the material. A division of these materials into seven large parts, however, provides a logical and convenient form for analysis. Chapter I- Introduction: This chapter provides a synopsis for the thesis and sets the stage for the types of problems and for the considerations that are necessary for their solution. This chapter introduces the topic in Kerala's context, its purpose and broad aim and its linkage to larger issue. Literature review, methodology of the work and hypotheses have been dealt in separate sub-chapters. Chapter 11- Analysis of Morphogenetic Processes: This chapter deals mainly with the analyses of morphogenetic processes highlighting on morphometric analysis of river Ittikara, slope profile, landform and identification of morphogenetic regions and it is discussed under appropriate separate sub-headings. Chapter III- Londuse: Analysis of landuse pattern is of ovemding importance in the context of physical and environmental resource assessment and it is dealt in separate subheadings. Landuse pattern of the total basin as well as of three sub-basins- Palliman Ar, Kulanji Thodu and Man Ar have been discussed in detail. Time-series landuse mapping of these sub-basins occupy an important part within this chapter. Cropping pattem along with crop combination within the basin area have been dealt with. Chapter IV- Demography: Demographic pattern of the basin area emphasizing on population density distribution and decadal growth has been discussed in this Chapter IV. Description of occupational structure of the working population is provided under various headings. Chapter V- Environmental Evaluation: This chapter deals with deforestation, soil degradation, hydrogeochernistry, environmental biogeochemistry, groundwater quality and sand and clay mining. A sample survey on critical area analysis is also included. Chapter VI- Geoecological Impact Assessment: This chapter puts forward geoecological impact assessment derived from parametric analyses and deductions of hypotheses discussed in proceeding chapters. Impact of landuse changes on water quality as well as on population density and impact of landform on setting landuse pattern have been discussed under separate sub-headings. Chapter VII- Conclusion: The concluding chapter advances the major findings of the study after analytically evaluating adoption of methodology and data source. Limitations felt on the methodology and data source have also been recorded. Finally, the study concludes by suggesting remedial measures for improving the situation faced by environmental as well as by anthropogenic dimensions.