Risk Evaluation of sinkholes in aquifers south of Isfahan province with emphasis on Karst points

Increasing water the demand for agriculture consumption, drinking and industry in recent decades has led to the drilling of water wells, which in many cases have been unlicensed. These uncontrolled withdrawals from groundwater sources in Isfahan province, along with the reduction of rainfall, have caused irreparable damage to the province's water resources and its dams are in danger of subsidence and sinking. Semirom city in the south of the province is one of the areas affected by uncontrolled abstraction of groundwater aquifers. In this study, by creating soil profiles in different parts of the region, identifying karstic environments, studying geomorphological characteristics and identifying authorized and unauthorized wells, groundwater level drop was investigated and the zoning risk map was prepared by fuzzy model. The results show the highest probability of occurrence of subsidence related to Kameh area located in Padna section in the southwest of Semirom city at a distance of 65 km from the city center. The subsidence hazard zoning map shows that 13.2% of the area in the risk zone is very high, 56.5% is high risk, 51.16% is medium risk and 13.2% is low risk. The results of hydrographic analysis and changes in the volume of water storage of aquifers and its evidence showed that the decrease in changes in the volume of aquifers in Semirom city is an average of 10.5 million cubic meters per year.