Scenarios to control land subsidence using numerical modeling of groundwater exploitation: Aliabad plain (in Iran) as a case study

The unconfined aquifer beneath the Aliabad plain is one of the few freshwater resources in northwestern Qom province in Iran. Land subsidence in the Aliabad plain is primarily the result of extensive overexploitation of groundwater resources and successive droughts. The harmful effects of overexploitation include significant socioeconomic consequences and severe damage to aquifers. The current study proposes an accurate scenario model that reduces the overall land subsidence by assessing different scenarios for future groundwater exploitation in the plain. The quantitative model consists of 120 time-steps over a period of 10 years (2006–2016). Model validation was achieved by comparing the calculated groundwater level variations with the results of piezometric evaluations in modeling. The results of the validated model were used to predict variations in the aquifer hydraulic head caused by changes in exploitation under different scenarios. Modeling of the Aliabad plain revealed that a 10% decrease in pumping will reduce and stabilize the groundwater decline and a 30% reduction will help recharge the aquifer. The model simulation was able to predict critical land subsidence of 35 cm by 2016. The geometric location of maximum land subsidence was predicted by comparing the geometric distribution of predicted land subsidence patterns with subsidence results from radar interferometry. Prediction of land subsidence by 2026 indicated that management of the exploitation of resources and strict aquifer stabilization programs can reduce the damage to the aquifer.