The Study of Environmental Effects of Nitrate Transfer in Varamin Aquifer Using Numerical Modeling

Quality assessment of the groundwater resources is one of the most important issues in water resources development. The main purpose of this study is to model the nitrate pollution, to recognize the spatial and temporal variations of nitrate concentration and to predict the nitrate movement under hydrological gradient. Thus, collecting and organizing the field data, formulation of hydrodynamic characteristics and transmission phenomena was conducted for the aquifer system in Varamin plain, Iran. In this study, a quantitative model of GMS software was prepared using MODELFLOW code and the qualitative data was imported to the model. The MT3D was used for modeling. According to the modeling results, it is predicted that during a 10-year period water from some zones of the aquifer will become non-potable. The most important factor in degrading the water quality in downstream of cities is the nitrate pollution from absorbent wells in residential areas in addition to the nitrate pollution from the agricultural areas in upstream. Due to the existence of an impermeable layer, confined aquifer is less affected by nitrate pollution in Varamin plain. According to the quality standards for drinking water, this aquifer is in an appropriate condition. It is suggested that drinking water be supplied from the wells recharged by the confined aquifer..