Optimization of Type and Location of the Management Practises to Contorol Nutrient Loads into the Water Bodies, Case Study: Lake Zrebar Basin

The main objective of this research is to optimize the type and location of Best Management Practices (BMPs) to reduce the amount of nutrients entering the lake Zrebar in order to improve lake conditions. In this regard, Simulation-Optimization approach derived from the integration of the SWAT model and a spatial optimization model of BMPs based on multi-objective genetic algorithm (NSGA-II) was used. In this approach, the optimal model of management practices was determined with respect to three maximizing the net profit of the agricultural sector, minimizing the nitrogen loads and minimizing the phosphor loads. In this research, a wide range of BMPs was investigated and the optimal spatial pattern of the management practices such as fertilizer, irrigation and tillage managements were determined. Results showed that by applying the selected management practices with the optimal spatial pattern, the total amount of phosphorus and nitrogen in the basin outlet decreased by 2.8% and 22.1% respectively and consequently the concentration of nitrate in the lake will be greatly reduced. Also the net income of the agricultural sector decreased by 16.4%. The results indicated that applying the selected management practices with the optimal spatial pattern can help to improve the environmental condition of the lake.