Groundwater vulnerability assessment using a combination of modeling and index rating method

Groundwater vulnerability map is a useful tool for water resources managers and decision makers to prevent water pollution and choose proper land use. Since, groundwater in arid and semi-arid region like Iran has an important role in water supply; therefore, it is important to protect it from being polluted by human. There are several different vulnerability assessment methods but overlay and index methods are most popular. These methods are not able to consider the physical process of the pollution. Therefore, methods based on modeling can help to overcome this deficiency. In this paper, a hybrid method including DRASTIC, one of the overlay and index methods, and groundwater solute transport model, was used to assess the vulnerability of aquifer in present and future. The model was run for 2 and 5 years and then multiplied to DRASTIC index. In this case, both hydrogeological characteristics of the aquifer and characteristics of the contaminant were taken into account. Astaneh aquifer was selected as case study to show the applicability of the proposed method and the selected contaminant was nitrate.