Abstract

Recent development of geographic information system (GIS) and remote sensing technology makes it possible to capture and manage a vast amount of spatially distributed hydrological parameters and variables. In this paper, a spatially distributed hydrologic model (WetSpa) is used to estimate daily river flow discharge and to analyze water balance of the Gorganrood river basin, Iran. The model combines topography, landuse and soil maps to predict discharge hydrographs and spatial distribution of hydrological parameters. For each grid cell the model holds water balance in the root zone by determination of soil moisture changes due to continues changes in infiltration of precipitation, runoff, initial absorption, evaporation transpiration, interflow, and percolation to the groundwater zone. The model gives all flow components at any cell, including surface flow, interflow and groundwater flow. The results show that the model is capable in reproducing water balance and its components. They also demonstrate the changes in the water balance during last two decades.

Key words: Water balance, distributed hydrological model, WetSpa, Gorganrood.