Assessment of groundwater contamination vulnerability in aquifer of Mashhad plain, Northeast of Iran, by using DRASTIC model in GIS

Groundwater is the most important resource of water supply in most part of Iran due to its climate conditions. Therefore, protection of groundwater resources from pollutions is essential. For this goal in this research, DRASTIC model in GIS has been applied, and the vulnerability map of Mashhad plain aquifer has been prepared. DRASTIC model includes seven hydrogeological parameters affecting the groundwater contamination. These parameters are determined, combined in GIS, and concluded to map of prone areas of contamination in the aquifer. Vulnerability of Mashhad plain aquifer to contamination is divided to five levels, from very low to very high which in terms of area, almost 9.1, 16.1, 14.4, 41.5, and 18.9 percent of the aquifer is determined very low, low, moderate, much and very much vulnerable respectively. According to the results of DRASTIC modeling, contamination vulnerability of Kashafrud aquifer is located in high to very high range mostly. Hence, the negative effects of city sprawl, municipal and industrial sewage without management and macro development planning should not be ignored. Although the amount of present contamination and the pollution potential of the aquifer are low to very low in east and northeast areas, they are high to very high in the center areas which needs more protection and optimised water resource management.