Karst hydrogeology of Karmustadj salt diapir, southern Iran

Karmustadj salt diapir (KSD) is located in the arid region of southern Iran. The karstic features of the KSD including vertical shafts, sinkholes, caves and brine springs, were investigated in order to characterize groundwater flow system in the diapir. KSD drains by three perennial and several temporary brine springs saturated with respect to halite. Electrical conductivity and chemical composition of three perennial brine springs were measured in wet and dry hydrological seasons. KSD consists of two hydrogeological units of Plug and Glacier districts. A conduit karst flow system is characterized for the Plug district including point recharge through sinkholes and discharge as several temporary brine springs. For the Glacier district, a diffuse flow system is proposed. Rainfall recharged to Glacier district discharges mainly via three brine springs throughout the year. The higher elevation of the springs of the diapir indicates that the elevation of base level of karstification is higher than the surrounding area, i.e. subsurface discharge of brine to the adjacent aquifers is unlikely. In this condition, construction of evaporite basins is proposed to prohibit re-infiltration of the emerged brine of the diapir into the surrounding aquifers which would increase water quality of the aquifers.