Assessment of Watershed Nutrient Load Input to Reservoir, a Case Study

Watershed modeling approach in water quality management and waste load estimation and allocation could be an effective way to improve the understanding of watershed-scale pollutant transport. Factors such as topography, land slope, land use and hydrological and metrological conditions should be considered. Using watershed models has the advantage of evaluating the possible impacts of changes in management practices to reduce the pollutant loads. In this article Aharchai watershed in North-western Iran has been modeled by Soil and Water Assessment Tools (SWAT), in particular, the nutrient load to Satarkhan reservoir is considered as an important element of the reservoir water quality. The model has been calibrated and validated for a three year field data. The results have been compared with the results of empirical models for estimating of non-point source nutrient load. The results could be used to recommend policies to reduce nutrient load into the reservoir.