Surface water quality modeling of Goorsuzan estuary in Bandar Abbas using SWMM rainfall-runoff model,

Due to population growth and industrial progress, the only important issue isn`t the lack of water resources, but besides that, the issues of runoff management, its quality, and urban wastewater management are also important. In this research, Khoorsuzan estuary located in Bandar Abbas city, Hormozgan province, was studied in terms of water quality. SWMM rainfall-runoff dynamic model was used for quality modeling of regional runoff. Hydraulic modeling was done for four precipitation events. The results of the sensitivity analysis showed that three parameters, percentage of impermeability of sub-basins, curve number and channel roughness coefficient, were the most effective parameters, respectively. Calibration and verification were done based on the objective functions of MRE and N.S. Its results were within the very good range of matching the model with the observational data for four times. Finally, qualitative modeling was done for four target pollutants, including COD, TDS, NO2 and PO4, and the qualitative results showed that the model was in good agreement with the observational laboratory data. At the end, three scenarios were considered to solve the problem. The first scenario showed the reduction of TDS pollutant concentration up to 84.52%. The results of the second scenario for COD, NO2 and PO4 pollutants reduced up to 100% and the application of the third scenario effectively reduced TDS, PO4, COD and NO2 pollutants. Based on the results of this research, the amount of water pollution around Khoorsuzan without wastewater management is more than the standard and the runoff from rainfall does not help to reduce pollution.