Predicting water level drawdown and assessment of land subsidence in Damghan aquifer by combining GMS and GEP models

It is over two decades that groundwater flow models are routinely implemented for better management of groundwater resources. Modeling groundwater flow with the help of the ground water modeling system (GMS) in the Damghan plain aquifer in northern Iran، which experiences declining levels and numerous environmental hazards، has demonstrated that، (a) in the worst case scenario the aquifer will face 320 cm of drawdown by year 2019 and (b) land subsidence is observed mainly in areas that are subjected to an accelerated water level drawdown rate، such as، the southern part of the aquifer. Four different rainfall scenarios that have been modeled demonstrate that some areas of the aquifer are slightly impacted by climatic change in contrast to some other areas that are being influenced substantially. Together with GMS، Genetic Expression Programming (GEP) and Multiple Linear Regression (MLR) models were used to forecast land subsidence by applying developing functional relations to the long-term groundwater drawdown data. This segment of the study shows that a 35. 4 cm and 39. 45 cm settlement will occur if the groundwater level drops by 295 cm and 343 cm، respectively. This research shows that the water level in the Damghan aquifer continues to decline and the land subsidence will intensify. It is، therefore، needed to reduce groundwater pumping in high-risk areas.