Identifying and Zoning of Groundwater Salinity using GIS Case Study: Namdan Plain of Eghlid County

The irregular takings of subterranean waters reduce water levels and change their quality. One of the effective parameters in determining the amount of groundwater change is the amount of electrical conductivity of water, so that with uncontrolled removal and reduction of groundwater level, the salinity of water increases, which entails irreparable damage to the animal ecosystem and plant life. In this research, we tried to study the amount of groundwater salinity of Namdan plain by determining the spatial analysis of its relationship with the deep and semi-deep wells in the plain. Therefore, the data of 32 observational wells in the plain area using an interpolation method in the GIS environment in order to determine the salinity of groundwater in 5 categories of very high, high, moderate, low and very low in the ten-year statistical period (2001-2010) were used. Then, by combining the information layers for all statistical years, the final decision regarding the determination of the salinity of groundwater was made. Finally, the relationship between the very high and high salinity zones with deep and semi-deep wells was investigated and it was found that among 1311 deep wells in the plain, 433 wells (33.02%) are in very high and high range, while for semi-deep wells it is 66/12%. In this way, it can be concluded that the position of deep wells and their unnecessary harvesting have a huge impact on the salinity of groundwater in the plain.