Electrical resistivity survey and chemical geothermometers methods were used to find the geothermal gradient energy potential of the Manghopir hot spring which is located in Karachi, Sindh. Schlumberger electrode configurations were used to demarcate the two shallow potential subsurface aquifers. At various depths, three lithological units were encountered: alluvium, sandstone, and shale. The first thermal water aquifer lies below at the average depth of 10m and average thickness of 9 m lies in sandstone lithology of Nari Formation of Oligocene age. The second thermal water aquifer encountered at the average depth of 68 m and the average thickness of aquifer was 40.5m in sandstone lithology of Nari Formation. The surface water temperature was calculated with digital thermometer which shows the range in between 48 °C to 50 °C and subsurface temperature was calculated with the help of chemical geothermometers. The Na–K geothermometers indicate the subsurface equilibrium reservoir temperature in the range of 135.52 °C,125.54 °C, 172.964 °C and 184.08°C and the Na-K-Ca chemical geothermometers indicate the subsurface reservoir temperature 148.493°C. The Na-K-Ca geothermometers show a high temperature, but the reservoir temperature appears to be lower due to the mixing of sea water with the chemical composition of hot spring water within the subsurface aquifers.

Geothermal water is increasingly used around the world for its exploitation. Bulk electrical resistivitydifferences can bring significant information on variation of subsurface geothermal aquifer characteristics. Theelectrical resistivity survey was carried out in Laki range in lower Indus basin in the study area to explore thesubsurface geothermal aquifers. The Schlumberger electrode configuration with range from 2 m to 220 m depth wasapplied. Three prominent locations of hot springs were selected including Laki Shah Saddar, Lalbagh and Kai hotspring near Sehwan city. After processing resistivity image data, two hot water geothermal aquifers were delineated atLaki Shah Sadder hot springs. The depth of first aquifer was 56 m and its thickness 38 m in the limestones. The depthof second aquifer of 190 m and with thickness of 96 m hosted in limestone. In Lalbagh hot springs two geothermalaquifers were delineated on the basis of apparent resistivity contrast, the depth of first aquifer zone in sandstone was insandstone 15 m and thickness 12 m, while the depth of second aquifer was 61m and thickness was 35m. In Kai hotsprings two hot water geothermal aquifers were delineated. The depth of first geothermal aquifer was 21m andthickness was 18 m and the depth of second aquifer was 105 m and thickness was 61m present in sandstone lithology.Present work demonstrates the capability of electrical resistivity images to study the potential of geothermal energy inshallow aquifers. These outcomes could potentially lead to a number of practical applications, such as the monitoring orthe design of shallow geothermal systems.

Groundwater is the primary source of drinking and irrigation water in the semi-arid region of Samaro Tehsil, District Umerkot, Sindh, Pakistan. However, the detailed information on aquifer geometry and groundwater quality has remained limited. In this study, the first integrated assessment combining Vertical Electrical Sounding (VES) and hydrochemical analysis to assess the subsurface aquifers and evaluate groundwater quality for drinking and irrigation purposes. Twelve VES surveys were conducted using the Terrameter SAS-4000 and subsurface resistivity models were interpreted using IPI2Win software. Groundwater samples collected from the corresponding boreholes were analyzed for major physicochemical parameters and irrigation suitability indices. The integrated interpretation showed distinct vertical salinity gradients with freshwater aquifers (10–30 Ωm) on top of brackish (3–8 Ωm) and saline (3 Ωm) layers at a depth of 20–30 m. Hydrochemical results showed that several groundwater samples exceeded WHO drinking water standards for TDS, sodium, magnesium, chloride, and electrical conductivity, whereas irrigation indices (SAR, KI, Na%, and MH) indicated potential long-term risks of soil salinization and reduced agricultural productivity. The combination of geophysical interpretations and hydrochemical assessment demonstrated the effective characterization of aquifer. This research provided the valuable information for groundwater resource management, sustainable irrigation planning, and future groundwater monitoring in the Lower Indus Basin.