Assessing groundwater vulnerability by pollution mapping in Iran: Case study Hamadan - Bahar plain

Abstract Groundwater is vulnerable to contamination by anthropological activities. Vulnerability mapping is considered as a fundamental aspect of groundwater management. Hamadan - Bahar aquifer located in the center of Hamadan province in western Iran, is considered as an economic priority resource due to its use in irrigation and domestic consumption. Numerical modeling of assessment of vulnerability and various hydrological indicators of potential pollution of water resources in Iran have been the subject of several studies since 2005. The application of various methods, DRASTIC, SINTACS, SI and GOD, showed that the most vulnerable zones were the southern and western part of the Hamadan - Bahar aquifer. The results showed that with DRASTIC, SI, GOD and SINTACS models, 7.1, 44.21, 29.56 and 20.16 percent respectively of the areas have high potential vulnerability. According to the DRASTIC model 33.6 % of the study area has a low class of groundwater vulnerability to contamination, whereas a total of 29.4% of the study area has moderate vulnerability. Accuracy of the models was evaluated using a linear regression between nitrate observation values and estimated vulnerability to pollution in measured wells. A significant correlation was observed between measured nitrate and pollution potential evaluated by DRASCTIC model p