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Contribution of electrical prospecting and spatiotemporal variations to groundwater potential in coastal hydro-sand beds: a case study of Akwa Ibom State, Southern Nigeria

George Nyakno Jimmy, Agbasi Okechukwu Ebuka, Umoh James Anthony, Ekanem Aniekan Martin, Ejepu Jude Steven, Thomas Jewel Emem, Udoinyang Ifiok Efiong

Acta Geophysica

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2023

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Vol. 71, no. 5

2339--2357

EN

The current study used vertical electrical sounding (VES), borehole (BH) data, Remote Sensing (RS), and Geographic Information System (GIS) techniques to identify groundwater potential zones in the coastal area of Akwa Ibom state, Nigeria, for the first time. This research aimed at producing groundwater potential zone map that can divide the study region into separate zones based on their groundwater potential ranking. The deployed method integrated VES procedure utilizing the Schlumberger electrode configuration some core samples for estimation of porosity, Satellite Shuttle Radar Topography Mission (SRTM), Digital Elevation Model (DEM), which served as input data for RS and GIS. Thematic maps of lineament density, lithology, land use and land cover, drainage density, and slope were created as GIS layers in a geo-database. Weightages were assigned based on a pair-wise assessment of the components that appear to be essential in retaining, storing, and transporting groundwater. The Analytical Hierarchy Process (AHP) was used in a GIS setting to merge five thematic maps of elements controlling groundwater occurrence and movement using weighted overlay. Results show that aquifers with high thickness and depths are clustering around VES 9, VES 14, and VES 15 that have the highest aquifer thickness in the range of 219–262 m and the highest aquifer depth in the range of 222.09–264.74 m. The highest aquifer resistivity in this area ranges from 2963 to 3683 Ωm. The hydraulic conductivity of the area is highest around the south-eastern part of the study area, with maximum value of 3.43 m/day. The transmissivity increases in the northern part of the study area, while the eastern parts showed the lowest values. The highest aquifer resistivity in this area ranged from 2963 to 3683 Ωm. Inference from analysis indicated that the most important element was soil type (43%), followed by lineament density (33%) and slope (13%). Land use/land cover was discovered as a marginal contributor to groundwater in the research region, accounting for about 4% of the total contributors. The study CR determined to be 0.043884, is much lower than the 0.10 consistency threshold and hence the justification of the results. The result of the overlay of the geophysical survey on the groundwater potential zones obtained from the RS, GIS, and VES techniques done in the first time in the study area has shown seamlessly that the study area has high groundwater prospectivity for subsistent and commercial extractions.

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Integration of Delphi Technique and Analytical Hierarchy Process Method in Assessment the Groundwater Potential Influence Criteria: A Case Study of the Ba River Basin

Dang Tuyet Minh, Nguyen Le Tung Duong

Inżynieria Mineralna

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2021

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no. 2

91--102

EN

Water is a boon for all living beings over the world and groundwater is considered one of the indispensable natural sources of potable water. It is necessary to assess and predict the groundwater potential to provide insights for decision-makers for proper planning and management of groundwater. The occurrence of groundwater depends on hydrological, ecological, climate, geological, and physiographical criteria. The purpose of the present study is to choose and attribute scores to all various factors that affected groundwater prospects in the Ba river basin. Firstly, the Delphi method was applied in the expert-based survey to choose six parameters that are considered as influencing factors, namely, lineament density, rainfall, slope, land cover, drainage density, and geology. Then, the weights for the various factors were generated using the Analytic Hierarchy Process (AHP) approach which allows the pairwise comparison of criteria influencing the potential areas. The consistency analyses show that the findings were consistent with a previous study. The consistency and sensitivity analyses showed that the obtained results were coherent, providing the weight vector of the achievable criteria that affect the groundwater prospect in the study area. The study reveals that lineament density and slope are criteria affecting the most prominent groundwater occurrence with 35.1% and 20.1%, respectively. However, the influence of other factors (rainfall, land cover, drainage density, and geology) is not visible. These criteria are assigned to the small weights and do not have a significant influence on the groundwater potential. The study results provide baseline information, which needs to be taken into account to control and manage groundwater potentiality.

3

Speculation on the resilience of karst aquifers using geophysical and GIS based approaches (a case study of Iran)

Nassery Hamid Reza, Zeydalinejad Nejat, Alijani Farshad

Acta Geophysica

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2021

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Vol. 69, no. 6

2393--2415

EN

Employing the "resilience" term to groundwater is a formidable challenge. The situation is even more intricate for the karst aquifers which may act as surface water with low resilience, alluvial groundwater with high resilience, and a combination of both. The objective of this study is to assess the groundwater resilience and hydrogeophysical characteristics of Asmari and Ilam-Sarvak formations at Susan karst, south-west Iran. Hence, 260 vertical electrical soundings (VESs) were carried out with the Schlumberger array. The VES curves were interpreted, scored, and interpolated to produce a groundwater potential map. Moreover, a geographic information system (GIS)-based approach was employed, including six layers, i.e. distance to springs, elevation difference from springs, slope, lithology, fracture density, and fracture length density. The GIS criterial maps were generated, reclassified, weighted, and overlaid, such that a supplementary groundwater potential map was produced. The electrical resistivity values and degrees of smoothness of the VES curves depicted considerable groundwater potential for the Asmari formation. However, the groundwater potential of the Ilam-Sarvak formation may be attributed to the superficial fractured zones. On the other hand, the geospatial technology which is based on the surface indices represented enormous groundwater potential for both formations, especially for the Ilam-Sarvak formation. Finally, regarding the groundwater resilience, various hydrological characteristics occur for two karst formations in a small-scale region. The Ilam-Sarvak formation primarily behaves like the surface water with low resilience (conduit flow, low storage), and the Asmari formation portrays the features of the alluvial aquifers with high resilience (diffuse flow, large storage).

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Groundwater potential assessment as a preliminary step to solving water scarcity challenges in Ekpoma, Edo State, Nigeria

Ajibade Fidelis Odedishemi, Olajire Olabanji Olatona, Ajibade Temitope Fausat, Fadugba Olaolu George, Idowu Temitope Ezekiel, Adelodun Bashir, Opafola Omobolaji Taofeek, Lasisi Kayode Hassan, Adewumi James Rotimi, Pham Quoc Bao

Acta Geophysica

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2021

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Vol. 69, no. 4

1367--1381

EN

Water scarcity is a major challenge around the world, particularly in Ekpoma community, Edo State, Nigeria. The population depends on water vendors and reservoir tanks as a means of water supply. This study aims to make an assessment of groundwater potentials for efective and sustainable water resources management in Ekpoma. Seven criteria were considered to determine groundwater potentiality including slope, rainfall, land use, drainage density, distance to lineament, soil, and geology. According to their impact on groundwater, the parameters were grouped into fuzzy membership categories. The groundwater potentiality map was generated by overlaying the fuzzy members. Of the 101.2 km2 area of Ekpoma, the high, medium, and low potential zones cover 7.9, 6.4, and 85.7% of the total area, respectively. High and medium groundwater zones were identifed mostly on the outskirt of the built-up areas. These groundwater potential areas were discovered to be predominant around the lineament areas suggesting that lineament plays a major role in the potential for groundwater in the study area. Reservoirs can be assigned in these high potential areas. Conclusively, the generated groundwater prospective map can be exploited for hydrological policy making and also by water supply engineers to predict the availability of groundwater.

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Estimation of groundwater potential using GIS modeling in Kohistan region Jamshoro district, Southern Indus basin, Sindh, Pakistan (a case study)

Memon Aneela, Ansari Kamran, Soomro Abdul Ghani, Jamali Muhammad Afzal, Naeem Babar, Ashraf Arshad

Acta Geophysica

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2020

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Vol. 68, no. 1

155--165

EN

The subsurface groundwater potential was calculated through the Geographic Information System (GIS) tool in district Jamshoro, Sindh, Pakistan; research was carried out in the vulnerable and arid climatic regions of the study area, which experienced unpredictable droughts and extreme foods. The primary recharging source of the aquifer is rainfall only in monsoon season from July to September. The current situation of water resources is critical in the region; in the present research work, two principal groundwater aquifers were encountered present in lithology of Laki formation mostly in sand and gravel lithology, which are shallow and deep aquifers. The GIS has been employed as a preservative tool to estimate groundwater potential. The estimated groundwater potential was 29,330.22 million cubic meter (MCM) under the monitoring area of 3207.25 square kilometers (km²); thus, the volume of groundwater was 9.14 MCM/km² in the selected cluster zone of the study area. It is realized that using a GIS tool combats the susceptible situation and shows authenticated results of groundwater potential.

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Assessment of groundwater potential through vertical electrical sounding at Haji Rehmatullah Palari village, Nooriabad

Soomro Asadullah, Qureshi Abdul Latif, Jamali Muhammad Afzal, Ashraf Arshad, Arain Asfand Yar Wali

Acta Geophysica

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2019

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Vol. 67, no. 6

1605--1623

EN

The study was conducted to assess the groundwater potential at Haji Rehmatullah Palari village aquifer, Union Council Sari of Kalu Khuhar along M-9 Motorway near Nooriabad, Sindh, Pakistan, through vertical electrical sounding (VES) by using Schlumberger electrode array method with 02–210 m. The collected data of 12 VES were interpreted by using IPI2win software. Monsoon rainfall period is very short, which starts from July to September (every year in Pakistan). Average rainfall is 150 mm with variation of 25 mm, in some year zero rainfall. During summer season, the evaporation and transpiration rate are about 70%, while the infiltration rate is 15%. Kalu Nadi (hill torrent) is the only source of recharge of this aquifer that depends on the rainfall. Lithological logs interpreted that mostly aquifers are present in sandstone lithology of Nari Formation which hold these freshwater aquifers having minimum 50 m thickness and have great potential for freshwater exploitation. Lithological logs interpreted that mostly aquifers persist in sandstone lithology of Nari Formation which hold the freshwater. Totally, five tube wells were installed at this aquifer and discharging the freshwater of about 98.55 million gallons per year and rapidly depleting the aquifers. Water business is also observed at this aquifer which was breaking influenced on the aquifer without considering the agricultural development to protect the environment. The aquifer is under pressure to drawdown and may suffer with its quantity and quality, if this trend continues.