The effects of exploiting aquifers on the quality of groundwater resources (Case study; Neyshabour plain, Northeast Iran)

The present study evaluated the effect of aquifer exploitation on the quality of groundwater resources in Neyshabour Plain (Khorasan Razavi). In this research, the qualitative and quantitative changes in water in observation wells were investigated over a period of 10 years. In order to better understand the changes in water quality, a chemograph diagram and Shuler and Wilcox diagrams were used. According to these diagrams, the quality of underground water in Neyshabour plain varies from good to completely unpleasant for drinking purposes, and about 27% of the samples are in C4-S4 and C4-S3 categories, which are very salty and is not suitable for agriculture. According to the chemograph schematic diagram, the average electrical conductivity had an increasing trend through the years 1389 to 1399 from 3600 micromos/cm to 3800 micromos/cm. The highest values of EC are in the western part of Kal-Shor. Significant amounts of silty-clay sediments with evaporative salts, placement in the catchment basin and small morphological slope have reduced the water quality. The results show that with the excessive use of groundwater in the last ten years, the water level has decreased 1.29 meter on average annually. Based on the results of this study, which indicates the decrease in the groundwater level and water quality in the study area, it can be mentioned that with the current trend, there will be numerous environmental effects, such as the reduction of irrigation or the drying up of springs, qanats, and wells, change of land use, cultivation pattern and land subsidence in the region in the future.