Groundwater exploration in the Garachay river basin using vertical electrical sounding method

Abstract

Since Azerbaijan is located primarily in a semi-arid zone, water shortages have always been a problem. Beginning from the second half of the 20th century, rapid population expansion and economic growth have further increased water demand. The geophysical survey in the Garachay river basin using the Vertical Electrical Sounding aimed to provide high-quality fresh groundwater for the nearby settlements. The geological section was dissected in detail. It consists of 8—10 layers of alternating boulder-pebble rocks with thin clay layers. The geological section of the study area is plicatively differentiated. Each identified aquifer is underlain by an impermeable layer, in which rocks are mostly composed of clay. The thickness of the alluvial deposits changes between 1—12 m and their specific electrical resistivity were determined to be 50—450 Ohm‧m. The resulting map shows an increase in the thickness of alluvial deposits from the northwest to the southeast. The main physical parameters, such as natural moisture content, density, the density of rocks under water, and filtration coefficient have also been determined. In the right-bank part of the study area, the sediment filtration coefficient varies between 1—3 m/day,
while in the left-bank part, it ranges from 6 to 12 m/day. The constructed 3D models clearly demonstrate how the electrical resistivity of the rocks that make up the geological section decreases from the surface down. This is presumably due to an increase in natural rock moisture with depth or an increase in clay particles content in the deeper layers. All of this suggests that the study area is promising for fresh groundwater exploration.