Application of Electrical Resistivity Survey and GIS for Hydrogeological Analysis and Salinity Zoning-A Case Study of District, Okara, Pakistan

Abstract

Numerous groundwater management concerns have arisen as a result of excessive groundwater use. The yearly pumpage has already exceeded the annual safe yields in certain regions, which has caused the water table to drop. Due to continuing, intensive groundwater pumping in Punjab, Pakistan, the quality of the groundwater is declining. Vertical Electrical Soundings (VES) were used to conduct geoelectrical resistivity survey investigations at District Okara, Punjab, Pakistan. The tool used for the collection of data was ABEM Terrameter SAS 4000, Sweden. To evaluate the spatial inconsistency of soil and groundwater quality Schlumberger array was used. Overall field data was collected from 28 different locations of the study area. The computer software “Interpex IX1D” was used for the interpretation of field apparent resistivity to true resistivity values and corresponding thickness of sub surface layers. Geographic Information System (GIS) was used for the mapping of groundwater quality at 50 m intervals by employing Inverse Distance Weightage (IDW) interpolation technique. The results shows that the uppermost layer of 0 – 50m comprised of maximum potential of fresh and useable quality water. In addition, as we increase the investigation depth and move away from the river i.e. center of district Okara, the resistivity values shows a decreasing trend reflecting the saline groundwater.