Document Type : Research Paper
Evaluation of water quality for water resources management is absolutely necessary.Non-point pollution are important in determining eutrophication of fresh water. The principle causes of this issue is high concentrations of nutrients in the water resources especially nitrogen and phosphorus. Understand the relationship land use and affecting factors in phosphate transport are the priority to assess the phosphate and predict its effect on surface water quality. Therefore, in this study the Soil and Water Assessment Tool (SWAT) was used for the simulation of phosphate in the Tajan watershed. Forest, agricultural and pasture, respectively contribute 54, 19 and 24 percent of the area and 24, 24 and 44 percent of phosphate. Among the agricultural cultivations, wheat fields produce the lowest load. Following the results in all land uses except pasture the main mechanism of phosphate transport has been from the sediment. The results of this study could be useful guide in order to preserve and protect the ecosystem of Tajan watershed from more degradation and promote sustainable development in this region.