Detecting the groundwater qualitative preservative extent by contemplating the vulnerability of aquifer

All over the world, most of the drinking water supplies from groundwater resources are continously threatened by various pollutants. In this study, the groundwater qualitative protective zone is defined by using MODFLOW, WhAEM۲۰۰۰ and DRASTIC models. At the beginning, the conceptual model of Rudan plain aquifer was made by MODFLOW and the values of recharge, hydraulic conductivity and Specific yield coefficient were calibrated. The steady model was initialized for ۱۳۸۹-۹۰ hydrological year as well as unsteady model for ۱۳۸۹-۹۱ hydrological years were made as the root mean square error for steady model was equal to ۱.۴۹ and for unsteady model was ۲.۳۲. Then, groundwater qualitative protective area was determined by using WhAEM۲۰۰۰ model in both constant radius and analytical methods. Finally, the vulnerability proportion of the aquifer was identified and it was considered for determining the qualitative protective extent. Results showed that most of the wells are located in the highly vulnerable zone with agricultural land use. Thus, Because of the high risk of groundwater pollution, extra transfer time for groundwater (about ten years) must be considered for determining the protective section. Also, for less vulnerable areas and other land use areas, a smaller protective zone can be applied, since the applying a greater zone in these areas will lead to a lot of social and economic costs. Based on previous studies, the main challenge for using the WhAEM۲۰۰۰ model to detect the qualitative protective district for drinking water wells is to determine the precise values of aquifer attributes and the basis for judging aquifer pollutant travel time. In this paper, we specified a more precise protective area by applying a calibrated groundwater model in GMS software as well as determining the vulnerability of aquifer by utilizing the DRASTIC model. Finally, according to the stated points, three immediate protective zones, mandatory and protective zones were determined for drinking water wells.

کلیدواژه ها:

DRASTIC ، WhAEM۲۰۰۰ ، MODFLOW ، Aquifer vulnerability ، GMS