Groundwater level changes effect on the subsidence in Semnan plain

Semnan plain is located on the northern edge of Iran's central desert and has a semi-arid climate. In recent decades, rapid population growth, increasing Industrial areas and water demand has led to excessive extraction of groundwater resources. As a result, the crisis of the severity of the decline in groundwater levels and ground subsidence in Semnan plain was reported. Satellite imagery interferometry (InSAR) monitoring in the specific period of 2003 to 2004 shows that maximum of 133 mm of ground subsidence in Semnan city has been occurred. The factors affecting the ground subsidence of Semnan plain were investigated by drawing hydrographic charts of groundwater level using the results of 15 observational wells. Continuous drawdown of groundwater levels can be seen during the water period of 2003 to 2009. Minimum rate of decline in groundwater level equal to 22 centimeters per year was reported. Merging the results of ground subsidence and decline of groundwater level illuminated the exploitation of groundwater resources over the aquifer recharge rate which increases the effective stress in soil layers and thus sediments high consolidation. This was the key factor for subsidence in Semnan plain with respect to the geotechnical properties of the aquifer. Therefore, water resources management was recommended for sustainable development of agriculture and industry.