A Study of the Gypsum Solubility of the Gachsaran Formation in East of Khuzestan Province and its Environmental Impacts

The Gachsaran evaporate formation is extensively exposed in East of Khozestan Province and the gypsum rocks in this formation show karstification. This paper has studied the development and environmental impact problems of gypsum karst in Ramhormoz and Meaedavood cities based on field study, laboratory and software studies. Structural factors such as joints, fractures and faults and the extraction of groundwater are the main agents in the development of karst gypsum. Due to the dissolution of gypsum, there is an increase in TDS and sulfate ions and a decrease in the quality of surface water and groundwater. The extraction of groundwater and lowering of the water table have increased the dissolution rate of gypsum and created a sinkhole. During recent years, a large number of sinkholes have been formed suddenly in the gypsum but, fortunately, have not caused any damage. Dissolution of the gypsum has caused an increase in the salinity of soil and expansion of saline land in Ramhormoz plain. As a result of the dissolution process, the resistance of rock decreases and cracks and fractures develop for the passage water, creating abundant slope instability in the Jareh Dam reservoir.