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University
of Ljubljana
EGU General Assembly 2011, Vienna, 3. - 8. April 2011, Session HS9.8
Faculty
of Civil and
Geodetic Engineering
Development of knowledge library for integrated watershed modeling
Nataša Atanasova2,3
University of Algarve, ICCE
[email protected]
Mateja Škerjanec1
University of Ljubljana
[email protected]
1
University of Ljubljana, Faculty of Civil and Geodetic Engineering, Jamova 2, 1000 Ljubljana, Slovenia
2 University of Algarve, Centre for Marine and Environmental Research (CIMA), Campus de Gambelas, 8005-139 Faro, Portugal
3 International Centre for Coastal Ecohydrology (ICCE), Solar do Capitão Mor, EN125 Horta das Figuras 8000-518 Faro, Portugal
1. INTRODUCTION
2. KNOWLEDGE LIBRARY STRUCTURE
The purpose of watershed modeling is to simulate the impacts of
different watershed activities on the state of the nearby aquatic
ecosystems. Watershed simulation models typically integrate different
process-based models, GIS tools and data management techniques. The
utilization of this kind of models is very difficult because of the broad
temporal and spatial scales that must be considered, as well as the large
amount of data that has to be pre-processed.
The modeling knowledge was encoded to the library by using a formalism that supports sufficient knowledge representation for integrated
watershed modeling and is structured in a way that enables a linkage between watershed modeling and ecological modeling of aquatic ecosystems.
In this research we are addressing these problems by developing a
generic modeling knowledge library that covers the domain of
integrated watershed modeling and can be used by automated modeling
tools.
WATER BALANCE
- Precipitation
- Evapotranspiration
- Surface runoff
- Percolation
- Groundwater discharge
- Deep seepage
NUTRIENT LOADS
Dissolved loads
- in surface runoff
- in groundwater
- in septic effluent
- in point sources
Solid loads
- attached to sediment
- in urban runoff
Figure 1: Division of processes encoded in the library.
ECOLOGICAL PROCESSES
Population dynamics of
phyto- and zooplankton
- Predation
- Growth
- Mortality
The library contains definitions of all the basic elements of the system (e.g. water, sediment, nutrients, etc.) and processes that represent relations
between these elements. The processes encoded in the library can be divided into three main groups (see Fig. 1):
- processes that maintain water balance,
- nutrient transport processes and
- ecological processes of aquatic ecosystems.
The formulations of the processes that are currently included in the
library are mainly taken from the GWLF model (Haith et al., 1992) see Fig. 2.
Moreover, the library includes alternative formulations for specific
watershed processes, which enable selection of the most appropriate
model structure for a given watershed. For example, process potential
evapotranspiration (PE) can be modeled using two different
equations:
0.021 H  e
A) PE 
T  273
2
0.023  H0  Tmax  Tmin   Tav  17.8 
or B) PE 

0.5
Evapotranspiration
Precipitation
Urban runoff +
point sources
Septic
effluent
Surface
runoff
Soil
erosion
Unsaturated zone
Percolation
Groundwater
discharge
Shallow saturated zone
Seepage
Figure 2: Schematic representation of the hydrologic and the nutrient cycle - approach used by GWLF.
In equation A (Harnon, 1961) H is a number of daylight hours per day, e is saturated water vapor pressure and T is a temperature on a given day. In
equation B (Hargreaves et al., 1985) H0 stands for extraterrestrial radiation, Tmax, Tmin and Tavg for maximal, minimal and average temperatures for a
given day and  for latent heat of vaporization.
3. TESTING THE LIBRARY
The library has been tested on a semi-hypothetical case study comprising a simple
catchment.
First the modelling task was specified which contained the information about the
(in)dependent variables and the expected processes in the observed system. Afterwards a
search algorithm was employed to extract the models from the library. The focus was on
the nitrogen loading model in the connection with the ecological model of aquatic
ecosystem, i.e., the phytoplankton model (see Fig. 3).
REFERENCES:
Water
Nutrients
Modeling task
specification
Library
containing generic
watershed modeling
knowledge
containing information
about the specific system
4. CONCLUSIONS AND FURTHER WORK
With the knowledge library developed within this research we are establishing a new
integrated watershed modeling approach based on a structured and formalized
watershed modeling knowledge.
Search algorithm
Future work will focus on:
Models
Figure 3: Library testing procedure
Haith, D. A., Mandel, R. and Wu, R. S. 1992. GWLF – Generalized Watershed Loading Functions, Version 2.0. Users manual. Ithaca, Cornell University.
Hargreaves, G. L., Heargraves, G. H. and Riley, J. P. 1985. Agricurtural benefits for Senegal River Basin. Journal of Irrigation and Drainage Engineering 111,2: 113-124.
Harnon, W. R. 1961. Estimating potential evapotranspiration. In: Proceedings of the American Society of Civil Engineers, Journal of the Hydraulics Division 87, HY3: 107-120.
- testing the library on more complex (real) catchments,
- addition of alternative formulations for specific processes and
- application of the library for induction of watershed models.
The models extracted from the library will be later integrated in the decision support
systems for integrated water resources management.