Evaluation of management scenarios for land subsidence reduction and groundwater rehabilitation in Damane-Daran plain, Iran

Abstract

Land subsidence by excessive groundwater extraction is one of the most important issues that many countries face. In the recent two decades, Damane-Daran aquifer in Iran faces severe land subsidence, caused by excessive groundwater extraction. This study investigates and presents management scenarios to rehabilitate and balance the aquifer. In this regard, a 3D model of groundwater and a 1D model of land subsidence is developed. Our designed scenarios include I) continuing the current trend in water extraction, II) reducing water extraction by 25%, III) reducing water extraction by 50%, IV) reducing water extraction by 75%, and V) increasing recharge in critical subsidence area by 200%. Our results show that the land subsidence trend follows groundwater level changes. This relationship is however non-linear and apart from the groundwater level, it depends on different parameters such as alluvium thickness, storage coefficient, etc. We show that continuing the current water extraction can cause maximum subsidence of 0.65 m in the aquifer. Through the employment of scenarios II to IV, this amount reaches 0.52 m, 0.41 m, and 0.31 m, respectively. Scenario V is the only successful scenario in aquifer quantity rehabilitation, but it does not affect the land subsidence balance. To prioritize the scenarios, scenario IV is the most favorable scenario, followed by scenario III, scenario II, and scenario V. Furthermore, results show that those parts of the aquifer with the highest subsidence rate are mostly associated with the agricultural fields in the eastern and central parts of the aquifer.