Numerical Simulation of Lahijan-Chaboksar Coastal Aquifer: Investigating the Possible Future Scenarios

Groundwater resources have been one of the main freshwater suppliers in arid and semi-arid areas of Iran. Due to population congestion in coastal areas, these resources have been threatened by both natural events and human activities. The present study considers the simulation of Lahijan-Chaboksar coastal aquifer in Guilan province, Iran. Hence, a three-dimensional, heterogeneous and anisotropic numerical model has been developed using SUTRA. The model has been applied after the calibration and verification procedures. Different possible future scenarios including the water level reduction in land boundary with/without increment net exploitation of aquifer, desalination plant wastewater disposal into aquifer/sea and their effects have been simulated and evaluated. Results showed that 10 m reduction of water level in land boundary, led to about 6 m reduction of average groundwater level within 30 years but it has no remarkable effect on aquifer’s quality. At the same period, 10 m reduction of water level in dry border beside the increase of net exploitation of aquifer (5 times), led to 13 m reduction of average groundwater level and the quality of groundwater decreases. However, injecting the wastewater of desalination plant into the aquifer increases the groundwater level about 1.4 m, but the quality of groundwater extremely decreases, while discharge to the sea has no effect on the aquifer groundwater level and the quality.