Low Groundwater Potential Research Articles

Groundwater potential zonation using VES and GIS techniques: A case study of Weserbi Guto catchment in Sululta, Oromia, Ethiopia

Groundwater is an appreciated and vital natural resource in the world, and it is of the utmost essential for the growth and development of a country. Nevertheless, assessing the groundwater potential and its recharge region is still ambiguous due to the nature of groundwater. In this study, the groundwater potential of the Weserbi Guto Laga Qawe Catchment Sululta area was assessed using VES and GIS methods. For the model, thematic layers were generated from the geophysical investigation, existing maps, and field survey results and were integrated into the GIS environment to delineate the groundwater potential zones. Factors such as lineament density, drainage density, elevation or topography, slope gradient, aquifer resistivity, and lithology were derived, reclassified, and scaled to common ranges and assigned with appropriate weights. The groundwater potential zonation model of the site was produced by the multicriteria evaluation method. Accordingly, the geometrical interval method was utilized to classify the index into three zones (high, moderate, and low) to produce the map. The model result revealed that a large part of the study area fell into the high zone with 50.14 % (3669.99ha). whereas 35.85% (262.72ha) and 14.01% (1024.95ha) show moderate and low groundwater potential, respectively. The resulting map was validated using eleven existing water level data points and the result was found to be in good agreement with the model.

Delineation of Groundwater Potential Zones (GWPZs) in a Semi-Arid Basin through Remote Sensing, GIS, and AHP Approaches

Groundwater occurrence in semi-arid regions is variable in space and time due to climate patterns, terrain features, and aquifer properties. Thus, accurate delineation of Groundwater Potential Zones (GWPZs) is essential for sustainable water resources management in these environments. The present research aims to delineate and assess GWPZs in a semi-arid basin of San Luis Potosi (SLP), Mexico, through the integration of Remote Sensing (RS), Geographic Information System (GIS), and Analytic Hierarchy Process (AHP). Seven thematic layers (geology, lineament density, land use and land cover, topographic wetness index (TWI), rainfall, drainage density, and slope) were generated in raster format. After the AHP procedure and rank assignment, the thematic layers were integrated using the raster calculator to obtain the GWPZs map. The results indicated that 68.21% of the area is classified as low groundwater potential, whereas 26.30% is classified as moderate. Validation was done by assessing the water residence time data from 15 wells distributed in the study area. Furthermore, the Receiver Operating Characteristics (ROC) curve was obtained, indicating a satisfactory accuracy prediction (AUC = 0.677). This study provides valuable information for decision-makers regarding the conservation and sustainable management of groundwater resources.

Monthly Dynamic Groundwater Estimation using GRACE over Indonesia

Indonesia is an archipelago with tropical climatic conditions, and part of it has arid areas. Monitoring groundwater dynamics effectively and efficiently is one of the challenges in a large area. GRACE is the Geodesy satellite that collects the sub-surface data. GRACE data is one of the gravity anomaly data that can be used for groundwater dynamics detection. Monthly groundwater monitoring can be used to determine the dynamic pattern of terrestrial water storage. It can be used as a parameter for the detection and prediction of drought in a large area. This study aims to model Indonesia's monthly groundwater levels based on gravity anomaly with GRACE satellite data. Anomaly gravity in GRACE's data is the main parameter in monitoring groundwater dynamics. Based on the results of monitoring during January-December 2020, three groundwater conditions were obtained in Indonesia. These conditions always have high groundwater potential, areas with diverse groundwater dynamics, and low groundwater areas. This low groundwater condition occurs in arid areas. The dynamic groundwater pattern occurred in the same month and had a similar pattern every season observed from 2002-2020. For example, the East Nusa Tenggara region has nine months of low groundwater potential. The potential and prediction of drought can be anticipated following the results of monitoring groundwater dynamics. Monitoring and predicting drought by predicting groundwater dynamics using GRACE's data can be an efficient and effective alternative for mapping, especially in Indonesia's vast and water-dominated territory.

Groundwater potential mapping of Tawi River basin of Jammu District, India, using geospatial techniques.

The demand for water is increasing around the world due to population growth, urbanization, industrialization, etc., which is making groundwater a vital natural resource for meeting the growing demand for water. According to the central groundwater report, Jammu district has adequate groundwater potential (GWP) and comes under the safe category. However, the GWP has not been fully utilized, thereby leading to a water shortage in the district. Therefore, this study has been designed to examine the GWP zones in the Tawi River basin of Jammu district using geospatial techniques. For this, several GWP conditioning parameters, such as elevation, slope, geology, geomorphology, rainfall, soil, land use/land cover, topographic wetness index (TWI), drainage density, lineament density, roughness, and curvature, were utilized. The analytical hierarchy process (AHP) technique was used to evaluate the weights of the selected criteria after a pair-wise comparison of each criterion with the rest of the criteria. The result showed that the high GWP zone accounts for 21.98% of the area, the moderate zone covers an area of 40.54%, the low GWP area accounts for about 34.91%, and only 2.57% of the area lies under the very low GWP zone. The validation of GWP zones using 25 monitoring wells showed an accuracy of 80% in GWP modeling. The findings of this study may be utilized in meeting the rising demand for water in the region.

Evaluation of Topsoil Competence, Aquifer Types, Groundwater Prospect and Flow Pattern using Geoelectric Characterization for Part of Ogbomoso, Nigeria

Part of Ogbomoso Southwestern Nigeria was assessed using electrical resistivity method with a view to obtaining the subsurface geoelectric parameters (resistivities and thicknesses), categorizes the topsoil into different competence zones and evaluates the aquifer types, groundwater prospect and flow pattern. Fifty-four Vertical Electrical Sounding (VES) data were quantitatively interpreted using the partial curve matching technique to obtain the preliminary layer parameters which were further refined through 1-D forward modelling WinResist software package. The resulting final layer parameters were used to generate 2D geoelectric sections, isopach and isoresistivity maps and subsequently used to categorize the study area into different topsoil Competence, Aquifer types and Groundwater Potential zones. Static water levels of hand-dug wells in the area were used to generate the groundwater flow pattern. Four subsurface geoelectric layers were delineated. These were the topsoil, laterite, weathered/partly weathered layer (main aquifer) and fractured/fresh bedrock. The resistivities and thicknesses of the layers were 76-1858, 649-2021, 17-880 and 260-33385 Ωm and 0.4-4, 0.7-1.9 and 1.9-25.2 m respectively. The groundwater flow pattern in the area was NE-SW. The study concluded that incompetent to highly competent topsoil, weathered bedrock (main) aquifer unit/partly weathered/fractured bedrock aquifer and generally low groundwater potential with NE-SW flow direction underlay the study area.

Application of fuzzy analytic hierarchy process and geospatial technology to identify groundwater potential zones in north-west region of Bangladesh

Over the last couple of decades, excessive use of groundwater has caused the depletion of groundwater resources in many parts of the globe. The northwest region of Bangladesh, which experiences frequent dry spells and low rainfall, is in severe water-stressed condition. Without sustainable planning and management, this region might experience a severe water crisis. Therefore, this research aims at delineating potential groundwater zones in the Rangpur Division of northwest Bangladesh by analyzing ten topographical and hydrological features derived from the literature review. Related data and information are extracted from the Landsat 8 image, digital elevation model (DEM) data of USGS and other secondary sources. This study has employed the Fuzzy Analytic hierarchy process in the GIS platform to generate the result. The findings suggest that about 3647 km2 (22.3%) of the study area has very high groundwater potential. On the contrary, 4320 km2 (26.5%) areas have low groundwater potential. The highest groundwater potential sub-region is located on the eastern part of the study area along the Brahmaputra River. The lowest groundwater potential sub-region is located on the western part of the study area which is part of the old Barind tract. The results are validated with the receiver operating characteristics (ROC) curve statistics. The AUC value of 0.84 implies that the model has successfully identified the groundwater potential zone in 84% of cases. Validation of the findings was also performed by analyzing the correlation between groundwater potential index and the depth of water level from 80 different wells (R2 = 0.68). The findings would help policymakers and planners in sustainable planning and management of groundwater resources in the northwest region of Bangladesh.

Identification of Groundwater Potential Zones Using GIS and Multi-Criteria Decision-Making Techniques: A Case Study Upper Coruh River Basin (NE Turkey)

In this study, geographic information system (GIS)-based, analytic hierarchy process (AHP) techniques were used to identify groundwater potential zones to provide insight to decisionmakers and local authorities for present and future planning. Ten different geo-environmental factors, such as slope, topographic wetness index, geomorphology, drainage density, lithology, lineament density, rainfall, soil type, soil thickness, and land-use classes were selected as the decision criteria, and related GIS tools were used for creating, analysing and standardising the layers. The final groundwater potential zones map was delineated, using the weighted linear combination (WLC) aggregation method. The map was spatially classified into very high potential, high potential, moderate potential, low potential, and very low potential. The results showed that 21.5% of the basin area is characterised by high to very high groundwater potential. In comparison, the very low to low groundwater potential occupies 57.15%, and the moderate groundwater potential covers 21.4% of the basin area. Finally, the GWPZs map was investigated to validate the model, using discharges and depth to groundwater data related to 22 wells scattered over the basin. The validation results showed that GWPZs classes strongly overlap with the well discharges and groundwater depth located in the given area.

Assessing the impact of drought conditions on groundwater potential in Godavari Middle Sub-Basin, India using analytical hierarchy process and random forest machine learning algorithm

Severe drought conditions have affected ever increasing demand of water in Godavari Middle Sub-Basin of India. Thus, assessment of drought and its impact on groundwater potential zones is essential for effective management of water resource in the Sub-basin. We utilized site-specific factors for ascertaining the groundwater potential zones. Analytical hierarchy process (AHP) was used for assigning weights to the factors and preparing map of groundwater potential zones. One-month (meteorological), three and six months (agricultural) and twelve months (hydrological) droughts were determined using standardized precipitation index (SPI) during 1979–2013. Vulnerable drought zones were identified using weighted sum overlay analysis. Random forest (RF) algorithm was utilized for assessing the impact of drought conditions on groundwater potential zones. Validation of random forest was carried out by dividing groundwater potential and drought maps into training (80%) and testing (20%) datasets in Jupyter notebook Python IDE (Integrated Development environment). Findings revealed that nearly half of the area of the Sub-basin experienced low and very low groundwater potential. RF analysis revealed that the groundwater potential in the northern and southern parts of the Sub-basin was severely affected by drought during the study period. Random forest regression (R2 being 0.858) indicated high accuracy of the model. Thus, RF model has proved to be an effective tool for analyzing relationship between drought and groundwater potential zones. The other drought prone areas interested to attempt drought and its impact assessment on groundwater potential may find this approach useful for policy measures.

Comparison of gradient boosted decision trees and random forest for groundwater potential mapping in Dholpur (Rajasthan), India

In the drought prone district of Dholpur in Rajasthan, India, groundwater is a lifeline for its inhabitants. With population explosion and rapid urbanization, the groundwater is being critically over-exploited. Hence the current groundwater potential mapping study was undertaken to ascertain the areas that are more likely to yield a larger volume of groundwater against those areas that have poor groundwater potential and accordingly perpetuate the much needed damage control. Thematic layers for 14 groundwater influencing factors were considered for the study region, including elevation, slope, aspect, plan curvature, profile curvature, topographic wetness index (TWI), geology, soil, land use, normalized difference vegetation index (NDVI), surface temperature, precipitation, distance from roads, and distance from rivers. These were then subjected to an overlay operation, with the groundwater inventory which comprised of the locations of observational groundwater wells. The resulting geospatial database was then used to train two decision tree based ensemble models: gradient boosted decision trees (GBDT) and random forest (RF). The predictive performance of these models was then compared using various performance metrics such as area under curve (AUC) of receiver operating characteristics (ROC), sensitivity, accuracy, etc. It was found that GBDT (AUC: 0.79) outperformed RF (AUC: 0.71). The validated GBDT model was then used to construct the groundwater potential zonation map. The generated map showed that about 20.2% of the region has very high potential, while 22.6% has high potential to yield groundwater, and approximately 19.9–17.5% of the study region has very low to low groundwater potential.

Evaluation of Aquifer Protective Capacity and Groundwater Potential in Part of Iju, Akure-North, Ondo State, Nigeria

Groundwater potential and aquifer protective capacity of the overburden unit was evaluated in part of Iju, Akure North, Ondo State using integrated geophysical methods involving Very Low Frequency Electromagnetic (VLF-EM) profiling and Vertical Electrical Sounding (VES). Four major traverses were established of varying length extents. The VLF-EM measurements were taken along the four major profiles of 10 m station interval.Forty two (42) Vertical Electrical Soundings were also conducted with half electrode spacing varying between 1 and 100 m and interpretation was done using the partial curve matching techniques and computer aided iteration. Five subsurface geological units were identified from geoelectric sections, consisting of the top soil, lateritic, weathered, partly weathered and fresh basement layers consecutively. For the first layer, resistivityranges between 23 and 323 Ωm with values of thickness ranging between 0.5 and 2.2 m. The resistivity and thickness of the second (lateritic) layer range from 132 to 430 Ωm and 1.6 to 4 m respectively. The resistivity of the weathered layer ranges from 4 to 94 Ωm and variable thickness between 10 and 24.4 m. The fourth layer has a resistivity value range of 65 to 120 Ωm and thicknesses between 20 and 30 m. The basement bedrock (fifth layer) has resistivity values between 770 and 820 Ωm. The depth to bedrock ranges from 1.8 to 31 m. The geophysical data and the basement aquifer delineated were then used to evaluate the hydrogeological setting and aquifer protective capacity of the study area. The observation from the results shows that close to 70 % of the study area falls within the zones of low groundwater potential, 25 % falls within medium potential zones while only 5 % make up the high potential zones. 75 % of the study area constituted the weak to poor protective capacity zones.

Aquifer characterization and groundwater flow dynamics in the upper left bank of Jemma River catchment, Blue Nile Basin, Ethiopia

The complex nature of the Ethiopian aquifer requires detail, characterization, and analysis. Consequently, characterization of groundwater flow and major aquifer systems was conducted in the upper left bank of the Jemma River catchment in the Blue Nile Basin. The research area covered 1255 km2. The main objective of the research was to characterize the aquifer systems and groundwater flow dynamics of the area. The software applied during the research work were aquifer test, ArcMap 10.2, global mapper 17, AutoCAD, Exelis ENVI, geomatics, and rockworks. Pumping test data and spring discharge together with qualitative field description were used to classify the aquifer system. Accordingly, the different aquifer classes are fissured aquifer developed on basalts on the plateau (moderate to low groundwater potential), mixed aquifer (high permeability and very high productivity), fissured aquifer developed on basalts in the valleys (high permeability and low to moderate storage), porous and fissured sandstone aquifer in deep valleys, and localized aquifer with intergranular porosity and permeability (high permeability and high productivity). From the analysis of water level measurements of boreholes, hand-dug wells, and springs, the groundwater flow system is controlled by surface morphology and lineaments. Therefore, the groundwater flows from SE and S-SSE corner towards the N and NW corner of the catchment. Understanding groundwater dynamics and characterizing the aquifer in the catchment are very crucial which in turn help to manage the available water resource for domestic, industrial, and agricultural purpose. Besides, the research will be used to manage aquifers from depletion.

Assessment of groundwater potential using geophysical data: a case study in parts of Cross River State, south-eastern Nigeria

Groundwater potential of some parts of Cross River State, Nigeria, was assessed involving vertical electrical sounding (VES) and high-resolution aeromagnetic methods (HRAM). The VES and HRAM dataset were used to delineate the hydro-lithostratigraphic units and map the spatial distributions of geologic structures, respectively. The electro-stratigraphic sections revealed the various hydro-lithostratigraphic units composed of fractured/weathered crystalline basement, sandstones, siltstones, sandy shales, and highly baked and fractured shales occurring at different depths. Generally, the unsaturated top layer is composed of shales, marl, clay, silt, gravel and lateritic materials with resistivity ranging from ~ 3.0 to ~ 550 Ω m. This layer is underlain by various aquifer units like sandstones, siltstones, fractured shales and limestone/marl, and fractured/weathered basement occurring at different depths (~ 30 to ≤ 100 m) as revealed by the electro-stratigraphic sections obtained in the study area. In the Calabar Flank (CF), Oban Massif (OM) and Ikom-Mamfe Embayment (IME), the apparent resistivity for these hydro-lithostratigraphic units varied between ~ 8.50 and ~ 59.50 Ω m, ~ 120.2 and ~ 1562.6 Ω m and ~ 30.8 and ~ 277.2 Ω m, respectively. The enhanced total magnetic intensity maps and source parameter imaging result showed that the OM and IME are characterized by high concentration of short-wavelength anomalies, while the CF is dominated by relatively undisturbed thick sedimentation (~ 6217 m). HRAM results show that such areas are predominated by geologic structures like faults, fractures, fissure, dyke swamps, etc. caused by tectonics. Such geologic structures create secondary porosity and enhance permeability. From all the results obtained, OM and IME represent areas with moderate groundwater potential. The CF dominated by argillites with no significant tectonic activity is observed to have low groundwater potential.

Effect of Lineament and Drainage Orientation on Groundwater Potential of Moro Area Central Kwara State Nigeria

Objectives: This study investigates the effect of lineaments and surface water flow direction on groundwater prospect of Moro area of Central Kwara, Nigeria using landsat imagery, drainage pattern, and groundwater potential map in a bid to determine the causes of persistent borehole failure and low yield. The study involved the extraction of lineaments from Landsat Thematic Mapper (TM) satellite imagery and construction of drainage network. The geographic information system (GIS) environment was effectively used for the lineament analysis. The lineaments and drainage system were superimposed on an already existing groundwater potential map generated from vertical electrical sounding data in the area. The lineament map showed that most of the structures are found in the north-eastern and south-western parts while other areas were characterized by scanty and no lineaments (structures). The superimposition of lineaments on drainage patterns showed that they are not structurally controlled. The results obtained from the superimposed lineament and drainage system correlates reasonably with the groundwater potential map. The groundwater potential in the area was therefore characterized using the degree of interaction between the lineament and drainage system. The north-western, central and parts of the southern region of the study area were demarcated as having high groundwater potential while others are characterized with moderate potential except a small portion in the south-western part which is of low groundwater potential. It is inferred that the weak lineaments and drainage pattern interaction is responsible for the low recharge rate of aquifers resulting in low groundwater potential in some part of the study area. Keywords: Lineament, Drainage, Groundwater Potential, Moro Area, Orientation.

Delineating of groundwater potential zones based on remote sensing, GIS and analytical hierarchical process: a case of Waddai, eastern Chad

The delineation of favourable areas of water potentials and their management must be based on rigorous scientific studies. Thus, geographic information system (GIS) and remote sensing (RS) techniques are extremely important in predicting and mapping favourable groundwater zones. This paper aims to map potential areas of groundwater in Waddai region, eastern Chad. A region which has experienced successive droughts over the last two decades, causing the drying of most of the rivers in the area. This study focuses on combining GIS, RS, and analytical hierarchy process; in addition to the factors controlling the movement and retention of groundwater. Six factors (rainfall, slope, land use/land cover, drainage density, lineament density, and lithology) were used to integrate the spatial analysis of areas likely to hold groundwater. The results indicate that potential groundwater areas are unevenly distributed throughout the study area. For instance, the northwestern part is characterized by a low groundwater potential. This low potential in this part of the study area as well as a small portion of the eastern area is explained by a low density of lineaments and drainage, the presence of moderate precipitations, and a semi-permeable lithology (alternating hard rocks and loose sediments). While every low and moderate area occupy most of the middle of the region, good ground water reservoirs occupy a large part of the region. This distribution is explained by good fracturing, permeability, lineament density, high drainage, gentle slope, and precipitation. Therefore, areas of the northwestern part are highly suitable for groundwater exploration and exploitation. Hence; these results would be a guide for future explorations and will maximizes the economic efficiency of the ground water exploitation processes. Furthermore, this map will be useful as a guide in decision-making and on water policy planning.

Assessment of Groundwater Potential Zones by Using Geoinformatics in Angolelana Tera Woreda, North Shewa Zone, Ethiopia

Groundwater is the least known resource in terms of volume, location, quality, and spatial distribution. This problem is further aggravated in Ethiopia due to a lack of a groundwater spatial database system. The study was conducted in Angolelana Tera Woreda which covers a total area of 782.48 km2. The main objective of this study was to identify and delineate groundwater potential areas by using Geographic Information Systems (GIS) and Remote Sensing (RS) techniques. Multi-criteria decision analysis method in GIS environment was employed to identify groundwater potential zone. To do this, the geological, geomorphologic, slope, soil, lineament, land use/land cover and drainage density data were used. By integrating these data in GIS environment, therefore, groundwater potential zones were identified, and the output was classified as very high, high, moderate, low and very low potential zones. Based on the result, 109.2 km2 (12.9%), 129.53 km2 (16.55%), 435.52 km2 (55.66%), 63.28 km2 (8.09%) and 53.23 km2 (6.8%) of the study area has very high, high, moderate, low and very low groundwater potential, respectively. It can be concluded that relatively the study area has high groundwater potential. So in order to utilize this important resource for different uses, high resolution groundwater potential map and spatial based groundwater analysis techniques should be required. Therefore, the woreda administrator bodies and other concerned stakeholders who might utilize and manage the available groundwater resource of the study area should use this research output as an input to develop an overall master plan for groundwater exploitation and management.

Groundwater aquifer potential using electrical resistivity method and porosity calculation: a case study

ABSTRACT This study uses aquifer characteristics such as the aquifer thickness, depth to the aquifer, and the subsurface porosity calculated from 1-D vertical electrical sounding data to evaluate groundwater potential. Thirty geoelectric investigations were carried out using Schlumberger-vertical-electrical-sounding (VES). The VES data were plotted against their respective current electrode spacing (AB/2) and presented as curves. The curves were interpreted quantitatively by partial curve matching and 1-D computer-assisted forward modelling using the WINRESIST version1.0 software. Isopach and isoresistivity maps of aquifer units in the area were generated from 1-D vertical electrical sounding data. The investigated area was subdivided into three zones of high (C); medium (B) and low (A) groundwater potential. Zone A overburden thickness <20 m has 30%, zone B with overburden thickness <30 m, which is the most predominant occupies 55% while 15% overburden thickness for zone C is <40 m. The subsurface porosity is calculated using Archie’s Law. The aquifer in the northeastern and southeastern parts of the study area were determined to be of good quality and can yield reasonable quantities of water that can serve the community.

Integration of aeromagnetic and electrical resistivity imaging for groundwater potential assessments of coastal plain sands area of Ado-Odo/Ota in southwest Nigeria

This study aims to investigate the groundwater potential of Coastal Plain Sands area of Ado-Odo/Ota within Dahomey Basin using the integration of aeromagnetic method and electrical resistivity imaging. The aeromagnetic method is applied to reveal the possible hydrogeological structures (such as lineament or fracture) buried in the subsurface. The lineaments which are interconnected are observed in the eastern part of the study area while the western part is void of the interconnectivity of lineaments. Resistivity technique is applied in regions where there are interconnectivity and non-interconnectivity of lineament to delineate occurrence of groundwater about the observed lineament. The depths to magnetic sources range between 102.6 and 1965.2 m. Furthermore, the result of resistivity technique shows that the depth to aquifer ranges from 40 to 100 m with corresponding resistivity values that range between 150.0 and 350.0 Ωm in the region of the interconnectivity of lineament, which is the eastern part of the study area (Igboloye-Covenant University area) and had high groundwater potential. The western part which is void of the interconnectivity of lineaments (Alapoti area) ranges from 80 to 130 m with resistivity values that range between 250.0 and 450.0 Ωm suggesting that the area has low groundwater potential. The study, therefore, shows that the occurrence of groundwater in Ado-Odo/Ota community is a function of hydrogeological structures such as lineaments or fractures, and as a result, this information could serve as guide for borehole drillers, civil engineers and resident of the study area for proper planning before siting borehole either for domestic or industrial use.

Groundwater Potential Zone (GWPZ) for Urban Development Site Suitability Analysis in Bhopal, India

This study uses remote sensing, GIS and MCDA techniques for studying the availability of groundwater resources and their suitability for urban residential planning in Bhopal, the capital city of Madhya Pradesh, India. The first part of our research involves integration of nine different thematic layers in AHP to identify GWPZ. The study reveals that 13.51% of the area has very high, 13.77% of the area has high, 12.05% has medium-to-high, 27.61% of area has medium groundwater potential, while the remaining 33.05% has low groundwater potential. In the second part of the research, the resultant GWPZ is combined with eight different thematic layers for identifying suitable urban residential development sites. Urban residential site suitability map shows that only 16.97% of the area has very high suitability, 20.71% area has high suitability, 25.81% of the area has moderate suitability and 23.56% has low suitability, while the remaining 12.94% area is non-suitable.

Shallow aquifer potential mapping in the foothills of Churia in Eastern Gangetic Plain of Saptari District, Nepal

The population living in the foothills of Churia, the study area, faces severe water scarcity due to limited access to surface water. The only alternative is groundwater, and there is extensive use of groundwater for domestic and agricultural purposes. Groundwater in some areas is limited and very limited information pertaining to the aquifer. In this context, this research tries to answer the pertinent questions concerning the aquifer properties, depth and thickness of the groundwater aquifer layer and groundwater prospects for irrigation. The objective of this research is to identify the aquifer properties and groundwater prospects using two-dimensional electrical resistivity tomography methods (2D-ERT). Five 2D-ERT profiles were used to collect information to a depth of around 40 m, with minimum electrode spacing of 5 m over a profile length of 240 m. The survey was carried out using Wenner electrode configurations. The resistivity tomogram sections were interpreted using RES2DINV software, which provides output in the form of resistivity contours that are used to draw up the lithological and geological information. The result of the survey indicates that the areas with good potential for groundwater access exist mostly along the southeast to central east parts of the study area, where there is gravel and sand with resistivity values between 100 and 500 Ω m. Areas along the northwest with clay and silty clay formations have low resistivity values (< 70 Ω m) and low groundwater potential. While the northeast has high resistivity values (> 2000 Ω m) due to sand formation underlain by boulder and cobbles, it also has limited groundwater potential due to the limited depth (< 6 m) of sand and low storage capacity. The study reveals a variation in lithological formation, including a patchwork of clay, silty clay, sand, gravel and boulder materials, with varying groundwater potentials. When developing shallow tube wells in the study area, spatial variation in the productive aquifer, hydraulic conductivity of groundwater flow within and near the tapped aquifer and geological and lithological material need to be considered.

Geophysical and physicochemical investigation of groundwater repositories in Njaba LGA of Imo State, eastern Nigeria

Geoelectric survey integrated with physicochemical method of water analysis was used to investigate the aquifer repositories in Njaba, Imo State, eastern Nigeria. This was done in 15 locations using vertical electrical sounding (VES) employing Schlumberger electrode configuration, and water samples from four boreholes were analyzed in the laboratory. The resistivity data were interpreted using forward and iterative least square inversion modeling of WINRESIST software. Four to six geoelectric layers and the VES characteristic curve types were obtained. The resistivity values vary across the study area with their respective depths and thicknesses. The aquifer resistivities range from 402.50 to 16,484.40 Ωm. The hydraulic parameters estimated include: Dar Zarrouk parameters (longitudinal conductance and transverse resistance), hydraulic conductivity and transmissivity. The longitudinal conductance ranges between 0.0004 and 0.0763 Ω−1, and transverse resistance ranges between 6823.40 and 245,320.00 Ωm2. The range of hydraulic conductivity and transmissivity varies from 0.0450 to 1.4363 m day−1 and 0.3195 to 44.0944 m2 day−1, respectively. The contour maps generated using Surfer software package displayed the variations of these parameters across the study area. The results obtained indicate that the study area has low groundwater potential based on the transmissivity values and may be prone to surface contamination due to its poorly protected aquiferous units. The concentrations of the ions in the water samples measured were compared with the World Health Organization (WHO) standard for drinking water and were found to be below WHO standard. The sodium percentage and sodium absorption ratio were calculated in order to determine the suitability of the groundwater for agriculture.