Site Selection for underground dams using RS and GIS (Case study: Kashan Plain, Iran)

A suitable method of locating an underground dam according to physiographic factors ensures its operation in providing water resources for hot and dry areas without causing environmental issues. In this study, Remote Sensing (RS), and Geographic Information System (GIS) techniques were used to locate suitable locations for underground dams. To implement, several data layers; topography, slope, lithology, drainage, lineaments, and local Qanats of the region were collected using the Digital Elevation Data (DEM), and LANDSAT 7 ETM Satellite. The lithological layers were gained by means of a geological map of the 1/100000 of Natanz in Kashan plain. Regional lineament data were calculated and converted to a digital layer by applying directional filters on the ETM satellite data in four directions using ENVI (remote sensing software). A supervised classification tools in ENVI software were then used for mapping the lithological layers. Final map of the most suitable locations for the construction of an underground dam was prepared by weighting of the layers with the method of Analytical Hierarchy Process (AHP combined with the support of Weighted Overlay tool in a GIS. Following identifying the areas with high priority, seven convenient points were identified by visiting the area taking into account the accessibility, and the performances of the region. Of these, four points to reserve subsurface water, one point to increase watering of Qanats and two points to prevent reduction of subsurface water quality were selected.