Determination of Alluvial Sediment Thickness of Shahriar Plain Using the Geoelectric Sounding Method and Kriging Interpolation in the GIS Environment

Knowing the subsurface structures is one of the ways to access underground resources, and knowing the characteristics of alluvial sediments is very important for exploitation, management and control of underground water. Shahryar plain located in the west of Tehran city and south of central Alborz, which supplies an important part of Tehran city's drinking water, is covered with Quaternary alluvium. The purpose of this article is to determine the thickness of these alluviums. There are different geophysical methods to estimate the thickness of different layers of the earth to determine the characteristics of alluvial deposits, including the type, depth, thickness, etc., of this plain, the data of electric soundings includes: 12 profiles and 186 sections, received from the regional water organization, geological maps, and data DEM used. After checking and validating the data, by choosing the normal kriging interpolation method with exponential variogram, the alluvial thickness and topography maps of the underlying layers include: alluvial thickness map, evaporite sediment surface topography, tuff and igneous rocks topography, The topography of the bedrock of the region, the thickness of evaporite sediments and the topography of the conglomerate surface of the region were preparedin in GIS with the highest accuracy. Then horizontal and vertical characteristics of these deposits were investigated. The results showed the maximum thickness of the alluvium is up to 350 meters in the center And near the edge of the plain, the thickness of alluvium decreases so that it is about 10 meters in the west and southwest.