The City of Rey with a population of 1 million suffers from water crisis. Among different water resources, groundwater has a major role in supplying 40 to 50 percent of the city's drinking water. Therefore, its contamination must be studied both as a regional issue and as a threat to the social health.
In this study, nitrate is considered as the best index showing the groundwater contamination, especially due to the anthropogenic activities in the area. In studying the nitrate contamination of the groundwater, there were several problems such as the lack of proper data and the vastness of the case-study area.
This study focuses on contamination sources, saturated zones, and the quantity of nitrate discharged into the groundwater .The groundwater concentration in central and eastern parts of the city is 65 ppm.
The mathematical model (MT3D) makes it possible to predict the groundwater quality. The simulation results show that the concentration of nitrate will increase in the central and eastern regions, but a sewage collection network can reduce the concentration of nitrate by 30 ppm.