Determination of Strategic Water Resources in Hard Rocks of Saein Area in order to Supply Drinking Water for Ardabil City at a Critical Water Shortage

Abstract

Finding of new water resources is a strategic necessity for Ardabil City as the capital of a province. Because the Ardabil aquifer is faced with problems of negative water budget and drinking water supplied from Yamchi dam which provides 60% of Ardabil's drinking water has a low quality. Also, colonization of half of the province population in Ardabil city and population growth horizon are other key reasons to prepare new water resource for the city. Saein area was chosen for exploration of groundwater new resources for suppling of drinking water for Ardabil city, because of relative high annual precipitation, fractured rock distribution with suitable water quality and proximity to the water treatment site located adjacent to the dam and water convey line from Yamchi dam,. Volcanic units with pure fracture porosity have formed fractured rock aquifers with high quality groundwater. In order to determine the groundwater resources of the study area and preparing the potential zoning map, nine rasteric map developed according to nine main parameters including lithology, fracture density, height as precipitation and as basin area, moisture, slope, stream density, slope direction and vegetation coverage index. The rasteric layers have been overlaied using two methods, ordered weighted averaging (OWA) and weighted overlay methods. The resultant potential map was prepared with five order of zoning, very high, high, moderate, low and very low potential. Calibration of two resulting map with springs location showed that the OWA method is more consistant with the field findings. Olivine basalt, pyroxene bearing andesite and trachits have been covered the areas with high groundwater potential. Factures and faults have the second role in the rainfall percolation and forming of aquifers.