Exploration of strategic karstic and hard rock groundwater in order to supply drinking water for Miyaneh City in critical water shortage conditions

Germi Chai basin with an area of 926 square kilometers was regarded as a suitable area for water potential studies and water resources assessment due to lithology types, erosion climate condition, and tectonic setting which mainly affected by faults and other factors significant in recharging of aquifers. Information about 9 parameters, as a grid and fuzzy model, were prepared in GIS and ENVI software to determine the areas with ground water potential. Parameters lithology, fracture densities, stream densities, vegetation, slope and aspect, height with two factors of rainfall and area, and moisture index are among natural factors affecting water recharge into groundwater tables. Preparing GIS layers for the parameters and adopting four methods of AHP, SUM, Fuzzy Gamma, and Weighted Overlay, ground water potential maps of Germi Chai area were prepared. The results showed that areas with permeable lithology, high porosity and high fracture density have a fair potential for the formation of ground water recharge and formation of water resources. Accordingly, in the second stage, the four methods were reclassifying and weighted with the Weighted SUM method, and final map was prepared as a reference map. The final map was evaluated and verified by overlaying of springs and water production wells. According to the results 34.85% of the area of the Germi Chai basin has high and very high groundwater potential. The resultant map can be used for management of the aquifer and supplying drinking water for residential areas.