Providing DRASTIC maps to assess potential vulnerability in Kohnak aquifer using GIS

Abstract

Nowadays the study of regional groundwater resources, because of draught ,their optimal exploitation,<br />and reducing their pollution is a vital matter. A proper way to prevent the pollution of underground<br />waters is to locate vulnerable spots and to conduct an efficient exploitation of the ground. Using the<br />present models is very essential to locate and study about vulnerable spots. For this study, GIS and<br />DRASTIC methods were applied to study the pollution potential in Kohnak aquifer. DRASTIC model<br />is including seven layer : Depth of water, net Recharge , Aquifer media , Soil media, Topography ,<br />Impact of vadose zone and hydraulic Conductivity. these seven layers were prepared according to<br />well exploitation logs and other data pertaining to the soil and the rat of rainfalls by using GIS<br />software and the DRASTIC index (99.96-152.56) was calculated .Therefore the results show that the<br />research area in some parts have high vulnerability classes while the other parts were characteristized<br />by low vulnerability classes. Finally, it was proposed in areas with high vulnerability to possible<br />creation of a facility's potential to release pollutants to the aquifer such as refineries, industrial parks,<br />etc., must be avoided. As Well , the use of chemical fertilizers in this area should be limited to prevent<br />further damage to the aquifer .