University of Ljubljana EGU General Assembly 2011, Vienna, 3. - 8. April 2011, Session HS 9. 8 Faculty of Civil and Geodetic Engineering Development of knowledge library for integrated watershed modeling Nataša Atanasova 2, 3 University of Algarve, ICCE natasa. atanasova@icce-unesco. org Mateja Škerjanec 1 University of Ljubljana mateja. skerjanec@fgg. uni-lj. si 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, EN 125 Horta das Figuras 8000 -518 Faro, Portugal 1 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: A) Evapotranspiration Urban runoff + point sources Septic effluent Precipitation 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. or B) 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) H 0 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 Search algorithm 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, HY 3: 107 -120. 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. Future work will focus on: - 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.
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