A Development and Validation Process for Evaluation Potential to Pollution in Astaneh-Kouchesfan Plain, Sefīd-Rūd Basin, North of Iran Masoud Saatsaz 1+ , Wan Nor Azmin Bin Suliman 2 , Shaharin Ibrahim 3 and Koroush Mohammadi 4 1 Department of Geology, Institute for Advanced Studies in Basic Sciences(IASBS), 45195-1159, Zanjan, Iran 2,3 Department of Hydrology and Hydrogeology, University Putra of Malaysia, 43400 UPM SERDANG, Selangor, Malaysia 4 Department of Irrigation and Drainage Eng. Tarbiat Modares University 14115-336 Tehran, Iran Abstract Astaneh-Kouchesfahan Plain is one of the most important water resource systems in Sefīd-Rūd Basin, north of Iran. In the study, the groundwater potential to pollution was evaluated for Astaneh-Kouchesfahan Plain using GIS DRASTIC model. The assessment of intrinsic vulnerability to pollution using DRASTIC model shows that low, moderate, high and very high groundwater vulnerability risk zones cover around 12, 52, 28 and 8% of study area, respectively. Then, a solute transport model of the aquifer has been developed and calibrated using MT3D. The final results confirms that correlation between solute transport model and DRASTIC vulnerability model is good and developed model can be considered as effective tools for evaluating alternative options for the management of groundwater resources. Keywords: Aquifer vulnerability, DRASTIC model, Groundwater pollution, Sefīd- Rūd Basin, Iran, Model validation, Numerical modeling. Introduction The conventional approach to assessing vulnerability of groundwater to pollution reflects the properties of aquifer system, and defines the groundwater contamination risk. DRASTIC vulnerability index method is a groundwater quality model for evaluating the pollution potential of large areas using a combination of geologic, hydrogeologic, geomorphologic, and meteorological characteristics of an aquifer (Aller et al., 1985). In this study, an attempt was made to develop and validate a DRASTIC vulnerability model for Astaneh-Kouchesfahan Plain in Sefīd-Rūd Basin. Astaneh-Kouchesfahan Plain, one of the most important water resource systems in north of Iran, is geographically located in 35° 34' 00'' to 35° 48' 00" North latitude, 49° 30' 00'' to 50° 15' 00" East longitude and covering an area of 1300 Km 2 (Fig. 1).The area of concern is geologically located in the south Caspian Basin and known as a part of the Alborz tectonical range in Alpine Fold Belt (Darvishzadeh, 2002). The area of concern experiences warm and humid summers with mild winters and shows a typical pattern of Moist Subtropical Mid-Latitude Climate and it can categorized 9th International River Engineering Conference Shahid Chamran University, 22-24 Jan 2013, Ahwaz