ASSESSING THE RISK POTENTIAL OF SURFACE WATER POLLUTION BY WRASTIC AND NMED INDICES IN ArcGIS SOFTWARE ENVIRONMENT, CASE STUDY: ASTANE-KUCHESFAHAN

Assessing the pollution Risk Potential of Water resources and its zoning can produce useful information for water resources quality control. Generally, risk includes two features of vulnerability and susceptibility. Accordingly, high vulnerability along with low susceptibility may occur in an area and vice versa. In this study, the surface water pollution susceptibility (Astane-Kuchesfahan region) is analyzed by WRASTIC index and New Mexico Environmental Index (NMED) is devised to address its vulnerability. The required data are provided by the organizations, field studies, geographic information systems and then the surface water risk is assessed by entering this information in ArcGIS software. The results show that different sub-basins have different pollution risk and the existence of the industries, agriculture and household wastewaters are the most important limiting factors in the sub-basins with high pollution risk. According to the numerical values obtained, Sub-basins 1-10 are heavily polluted, Sub-basins 3, 5, 7, 11, and 12 are of low susceptibility, and the other areas are also with low sensitivity. In Sub-basins 1-10, which have a high pollution susceptibility index, the industrial activity factor accounts for the largest share due to industrial activities such as sand and gravel washing plants. It is also a major source of pollution affecting the sub-basin. In other sub-basins, factors like industrial and agricultural activities and untreated urban and rural sewage significantly contribute to pollution. The results obtained by using the NMED method and the number of pollutant sources indicate that in each buffer zone of the sub-basins, Sub-basins 3, 5, and 12 carry moderate vulnerability risk, Sub-basin 6 is of low vulnerability, and the other sub-basins have high vulnerability. According to the results, the method used in the present study is suitable for assessing the risk of surface water pollution and is considered to be a reliable method for surface water management and protection of surface water quality. Considering the high cost of the treatment of polluted surface water, the present study provides a very useful guidance for authorities to take key management decisions for preventing the uncontrolled expansion of industrial or agricultural zones posing risk of pollution in the sub-basins.