Groundwater Modeling by MODFLOW Model in Toyserkan Aquifer and Evaluation of Hydrogeological State under Present and Future Conditions

Groundwater resources are one of the most valuable natural resources. Therefore, in the recent years, the groundwater modeling is a powerful tool in management procedures, optimization and predicting of groundwater resources in future. The purpose of this study is the modeling of Toyserkan aquifer with MODFLOW that is a code in PMWIN software which is considered to be very efficient in groundwater modeling. The simulation was attempted for an annual period of 12 monthly stress periods (September, 2008 to August, 2009). This model was calibrated for first 10 months in simulation period and then was verified with observed data for next two months. Calibration results in steady and transient states indicate that, horizontal hydraulic conductivity and storage coefficient increases from north east to the south west in the Toyserkan plain. After verification to postulate the confidence from model’s ability for predicting the aquifer’s future conditions, two scenarios with 10 years length were defined. The first scenario is based on the current withdrawal trend and in the second scenario, irrigation efficiency which is increased up to 20 percent and therefore decreases in withdrawals was considered. A trend of decline in the groundwater levels in most of observation wells and increase in two observation wells, numbers 3 and 6 were observed.