Evaluation of aquifer parameters through integrated approach of geophysical investigations, pumping test analysis and Dar-Zarrouk parameters in the central part of Bari Doab, Punjab, Pakistan.

In the central part of Bari Doab in Punjab Province of Pakistan, the factors such as sporadic rainfall pattern, decrement of water in rivers, subsurface salinity and excessive mining of groundwater have badly affected the hydrogeology and recharge system of aquifer. The present research work is an endeavour to evaluate the characteristics and potential of aquifer for its future sustainable availability within the study area of central part of Bari Doab. The geophysical studies, pumping tests data, borehole logs and Dar-Zarrouk parameters were used integrally to evaluate the aquifer hydraulic and hydrologic parameters in the study area. VES technique of geophysical investigations using Schlumberger electrodes configuration was carried out at sparsely distributed 435 locations. Litho-logs and VES results altogether decipher that the subsurface alluvial succession is primarily composed of intermixed layers of sand, gravel, clay, silt and some kankar inclusions. The VES data allied with pumping test analysis of test wells in the study area were used to evaluate the aquifer hydraulic properties. Comparatively low values of discharge rate, hydraulic conductivity and transmissivity were evaluated in two wells whilst relatively higher values of these parameters were evaluated in rest of six wells. The results of hydrologic parameters also confirm the results of hydraulic parameters in the wells. Finally, the Dar-Zarrouk parameters were used for the estimation of hydraulic parameters for whole study area and the aquifer zones of relatively high and low potential were delineated.

Spatial appraisal of aquifer characterization through hydrogeophysical investigations in central part of Bari Doab, Punjab, Pakistan.

The study area lies in Southwestern part of Sahiwal District, Punjab, Pakistan, which is the central part of interfluves system, i.e., Bari Doab. Hydrogeophysical investigations were carried out for the spatial appraisal of groundwater aquifers resources in the study area through electrical resistivity survey. A total of forty vertical electrical soundings through Schlumberger electrode configuration are conducted in the study area. The interpreted results of electrical resistivity survey along with interactive modeling suggest that four to six numbers of geo-electric layers exist in the subsurface in the study area. The alternating alluvium comprised of silt, sand, gravel, and kanker layers has been interpreted. The interpreted resistivities are categorized from very high to very low in the study area. Below the water table, very low resistivity values interpreted mainly as sand and sand-gravel saturated with saline water. Moreover, the interpretation of our developed maps also leads to demarcate the fresh and saline groundwater zones. Interpreted results decipher that this gigantic saline water zone starts below the depth of 150 m and extends below the depth of 300 m. The models of true resistivities are also calibrated with the lithological logs of test holes and tube wells within the study area. The sandy and gravel layers are the most promising zones for good-quality groundwater that leads to the development tube wells up to the depth of 150 m within the study area.

The depositional setting of the Late Quaternary sedimentary fill in southern Bannu basin, Northwest Himalayan fold and thrust belt, Pakistan.

Geostatistical variogram and inversion techniques combined with modern visualization tools have made it possible to re-model one-dimensional electrical resistivity data into two-dimensional (2D) models of the near subsurface. The resultant models are capable of extending the original interpretation of the data to depict alluvium layers as individual lithological units within the 2D space. By tuning the variogram parameters used in this approach, it is then possible to visualize individual lithofacies and geomorphological features for these lithologic units. The study re-examines an electrical resistivity dataset collected as part of a groundwater study in an area of the Bannu basin in Pakistan. Additional lithological logs from boreholes throughout the area have been combined with the existing resistivity data for calibration. Tectonic activity during the Himalayan orogeny uplifted and generated significant faulting in the rocks resulting in the formation of a depression which subsequently has been filled with clay-silt and dirty sand facies typical of lacustrine and flood plain environments. Streams arising from adjacent mountains have reworked these facies which have been eroded and replaced by gravel-sand facies along channels. It is concluded that the sediments have been deposited as prograding fan shaped bodies, flood plain, and lacustrine deposits. Clay-silt facies mark the locations of paleo depressions or lake environments, which have changed position over time due to local tectonic activity and sedimentation. The Lakki plain alluvial system has thus formed as a result of local tectonic activity with fluvial erosion and deposition characterized by coarse sediments with high electrical resistivities near the mountain ranges and fine sediments with medium to low electrical resistivities towards the basin center.

Integrated study of quaternary aquifer for hydrostratigraphy and groundwater quality assessment in central Thal Doab, Punjab, Pakistan.

The groundwater resources in different areas of Pakistan are heading towards depletion along with the deterioration of quality due to over-abstraction and urbanization. The main focus of this study is to map the current hydrostratigraphical and hydraulic conditions of the late Quaternary aquifers in the central part of Thal Doab of Punjab Plains. To achieve the target, a comprehensive approach was employed combining geophysical investigations using electrical resistivity surveys (ERS) and physiochemical analysis of groundwater specimens collected from the study area. Careful calibration of resistivity models was performed by comparing them with lithologs to ensure their accuracy. The current groundwater conditions were assessed through thirty vertical electrical soundings (VES) using the Schlumberger electrode configuration up to 300m of AB/2. The interpreted results revealed the presence of four to six geo-electric sublayers comprising the intermixing layers of clay, silt, sand, gravel, and kankar inclusions. These layers exhibited very low (<20 Ω-m) to very high (>230 Ω-m) resistivity zones at various depth intervals. The developed 2D/3D models of aquifer systems identify the promising areas of good/fresh quality groundwater in the regions characterized by medium to very high resistivity mainly within the sand with gravel layers. However, lower resistivity values indicate the presence of marginally suitable/fair and saline/brackish groundwater showing the existence of fine sediments such as clays/silts. Additionally, twenty groundwater samples were collected to assess various parameters including pH, TDS, arsenic, fluoride, iron, nitrate, and nitrite. The spatial distribution of these parameters was visualized using 2D maps. The suitability of the groundwater for drinking consumption was evaluated in accordance with WHO guidelines.

Seismic attributes and spectral decomposition-based inverted porosity-constrained simulations for appraisal of shallow-marine lower-Cretaceous sequences of Miano gas field, Southern Pakistan.

Seismic attributes can play an important role in the exploration of hydrocarbon-bearing stratigraphic systems. Incised valley systems are developed during the falling sea, which causes the deposition of coarse-grained sandstone facies inside the low-standing tracts (LST). These regional phenomena constrain the quantitative attributes of ultra-thin-bedded stratigraphic petroleum traps, e.g., vertical and lateral variations in the thickness, accommodation space, lithology, and porosity. This study deals with the application of the continuous wavelet transform (CWT) of a spectral decomposition (SD) tool on a 3D post-stack seismic volume of the Miano gas Field, Lower Indus basin, Pakistan. The results show that the CWT accurately detected the regionally faulted/fractured system and distinguished the frequency-dependent amplitude anomalies. The wedge model resolved a 24-meter-thick gas-bearing resource. Quality control analysis was carried out using CWT-based broadband processing between the designed amplitude spectrum of 17 Hz and 70 Hz. The reservoirs with over 25% porosity that were located within the shale-dominated facies with less than 8% porosity were imaged through the processing of the instantaneous spectral porosity model at the 48-Hz tuning block. Moreover, 190 to 165-m-thick thin-bedded sandstone reservoirs at a 25% porosity zone were resolved using 22-Hz and 28-Hz, which implicates the sea standstill and medium-to-coarse-grained depositional reservoir facies. The ultra-thin-bedded traps inside the laterally continuous stratigraphic lens of 121 m and the prograding clinoform lens of 101-m within the incised valley petroleum system were resolved using 48-Hz, which implicates the falling sea and fine-scaled transgressed erosional facies. These implications suggest that the identified regional stratigraphic traps have development potential for this gas field. The treatment of the inverted model at the highest frequencies can be utilized to investigate the porous stratigraphically trapped facies of LST and can serve as an important analogue for the leading gas field of the Indus Basin and similar basins.

Hydrostratigraphy and hydrogeophysical studies to delineate fresh and saline aquifer boundaries in Lesser Cholistan of Pakistan.

The differentiation of saline water and fresh water interfaces is a key objective in ground water exploration and management. Bahawalpur is the twelfth biggest metropolitan area of Pakistan situated in south Punjab near the bank of River Sutlej and lies at 29°59'55" N latitude and 73°15'12" E longitude at an elevation of 521 ft AMSL in the Cholistan area close to the Thar abandon. The study area comprised of Lesser Cholistan experiencing acute shortage of water for inhabitants and livestock as well. The occurrence of fresh water is also challenging because of high salinity in groundwater. The present study is intended to identify hotspots of fresh groundwater zones. To achieve the goal, vertical electrical resistivity and borehole data are used to mark fresh and saline interfaces in groundwater. To achieve the results 230 vertical electric sounding were performed in the study area. A total of 3 to 5 geo-electric layers are identified with modeling along with the processing and interpretation of resistivity data. In the study area, resistivity values are classified as very high (>230 Ω-m), high (230-100 Ω-m), medium (100-40 Ω-m), low (40-20 Ω-m) and very low (<20 Ω-m). Borehole data is used to interpret subsurface lithologies and to calibrate the modeled resistivity curves. The electric resistivity data indicates that thick layers of Quaternary sediments is present in the subsurface that is primarily composed of clay, silt, sand, gravels and some kanker. Inversion technique is applied to generate 2D subsurface resistivity maps to delineate fresh and saline water zones. The generated 2D resistivity maps at variable depth above and below water table and formation resistivity maps are successfully utilized to differentiate fresh and saline water zones. The identification of a saline water aquifer within sediments rich in clay was made possible by the observation of very low resistivity measurements in the southern region. Conversely, the detection of relatively high resistivity values, coupled with the presence of sand and gravel deposits in the northern section of the lesser Cholistan area, provided compelling evidence of the existence of fresh groundwater. These findings have significant implications for the management of water resources in the region, as they provide valuable insights into the distribution and availability of groundwater resources for future use.