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Groundwater is essential for the sustainable growth of society, economy, and agriculture. Identifying potential zones for groundwater is required to fulfill the needs of various sectors. This study aims to identify prospective groundwater zones in the drought-prone Harawa catchment area of the Somali region of eastern Ethiopia using geospatial and analytical hierarchy process (AHP) approaches. Eight significant groundwater regulating variables were developed by combining primary and remote sensing data, and AHP analysis was performed to identify groundwater prospect zones. The findings of the prospective groundwater zone model were categorized into four groups: very low, low, moderate, and high. Approximately 14.2% of the research area was recognized as having high potential, 24.0% as having moderate potential, and 38.7% and 23.2% as having very low and low potentials, respectively. Groundwater prospect maps were examined and confirmed using the discharge data from numerous production wells in the study region. The results demonstrated a strong correlation or agreement with the yield data. The curve approach was cross-validated with the area, revealing an 81.7% correlation between the model findings and the water well points. The sensitivity analysis showed that lithology, land use/land cover, and rainfall significantly impacted groundwater occurrence. In contrast, the slope of the study region had little effect.

Groundwater is essential for the sustainable growth of society, economy, and agriculture. Identifying potential zones for groundwater is required to fulfill the needs of various sectors. This study aims to identify prospective groundwater zones in the drought-prone Harawa catchment area of the Somali region of eastern Ethiopia using geospatial and analytical hierarchy process (AHP) approaches. Eight significant groundwater regulating variables were developed by combining primary and remote sensing data, and AHP analysis was performed to identify groundwater prospect zones. The findings of the prospective groundwater zone model were categorized into four groups: very low, low, moderate, and high. Approximately 14.2% of the research area was recognized as having high potential, 24.0% as having moderate potential, and 38.7% and 23.2% as having very low and low potentials, respectively. Groundwater prospect maps were examined and confirmed using the discharge data from numerous production wells in the study region. The results demonstrated a strong correlation or agreement with the yield data. The curve approach was cross-validated with the area, revealing an 81.7% correlation between the model findings and the water well points. The sensitivity analysis showed that lithology, land use/land cover, and rainfall significantly impacted groundwater occurrence. In contrast, the slope of the study region had little effect. [ABSTRACT FROM AUTHOR]

Remote sensing imagery and geoelectrical surveys used in this study help to evaluate the groundwater potentiality in the metamorphic formations of the North Cameroon. The methodology of the work is then mainly based on the extraction and identification of lineaments or fracture zones which acts as the passageway for groundwater. Manual and automatic extraction technics applied on the Landsat-8 images made it possible to find sixty one (61) lineaments. The main directions of these lineaments are N-S and N22°E (NNE-SSW) and the secondary directions are N10°E, NE-SW, then W-E to N100°E. According to the lineament density map, high density values are located at the centre and at the western part of the study area. The lineament density contrasts show the level of fracturing in the area. This fracturing is also evidenced by the geoelectrical survey. Indeed, results of the electrical resistivity profiling and 2D electrical imaging around or near lineaments, reveal the existence of fractures and shear zones characterized by the conductive discontinuities in the electrical current responses. Usually, the discontinuities sus-evocated above form potential groundwater targets. So, based on the combined results from remote sensing and geoelectrical method, the present study thus demonstrates the effectiveness of using this approach for assessing the availability of potential groundwater zones in the metamorphic formations. However, methods used in this study should be supported by the drill hole methods for the validity of results.

In this paper, the performance of Artificial Intelligence (AI) in Geospatial analysis and GIS platforms for the prospecting of potential groundwater zones was evaluated in Fincha catchment, Abay, Ethiopia. Components of geospatial data under morphometric, hydrologic, permeability, and surface dynamic change were confirmed as the criteria for prospecting groundwater potential zones. The influence of the individual criterion was ranked and weighted in Artificial Neural Networks (ANN) training model and Analytical Hierarchy Process (AHP). The correctness of the weights fixed in the ANN and AHP was evaluated with target data assigned to the networks and consistency index (CI) respectively. The weighted overlay analysis in the GIS environment was implemented to generate the promising zones in both approaches (ANN and GIS). The results obtained in the ANN model and GIS were evaluated based on pumping rate and ground-truthing points. Groundwater potential zones of five and four classes were delineated in AI and GIS techniques respectively, and this is an indicator for the effectiveness of AI in geospatial analysis for prospecting of potential zones than the traditional GIS technique. The percentage of accuracy in both methods was measured from the ROC curve and AUC. Therefore, it was found that the delineated groundwater potential zones and the ground-truthing points were agreed with 96% and 91% in the AI and GIS platforms respectively. Finally, it is concluded that the ANN model is an effective tool for the delineation of groundwater prospective zones. [ABSTRACT FROM AUTHOR]

Remote sensing imagery and geoelectrical surveys used in this study help to evaluate the groundwater potentiality in the metamorphic formations of the North Cameroon. The methodology of the work is then mainly based on the extraction and identification of lineaments or fracture zones which acts as the passageway for groundwater. Manual and automatic extraction technics applied on the Landsat-8 images made it possible to find sixty one (61) lineaments. The main directions of these lineaments are N-S and N22°E (NNE-SSW) and the secondary directions are N10°E, NE-SW, then W-E to N100°E. According to the lineament density map, high density values are located at the centre and at the western part of the study area. The lineament density contrasts show the level of fracturing in the area. This fracturing is also evidenced by the geoelectrical survey. Indeed, results of the electrical resistivity profiling and 2D electrical imaging around or near lineaments, reveal the existence of fractures and shear zones characterized by the conductive discontinuities in the electrical current responses. Usually, the discontinuities sus-evocated above form potential groundwater targets. So, based on the combined results from remote sensing and geoelectrical method, the present study thus demonstrates the effectiveness of using this approach for assessing the availability of potential groundwater zones in the metamorphic formations. However, methods used in this study should be supported by the drill hole methods for the validity of results. [ABSTRACT FROM AUTHOR]

The scarcity of water is the major obstacle to sustainable development in poor regions under arid and semi-arid climate conditions. The search for reliable and less expensive methods for detecting potential water zones is of paramount importance. In this study, the approach based on remote sensing and geographic information system techniques and coupled with an algorithm of dynamic parameter weighting (ADPW) is found useful to develop a numerical model of the groundwater potentiality index GPI and to map areas suitable for setting future drill points in the Tafraoute region, western part of the Moroccan Anti-Atlas. This is a multi-criteria approach based on the analysis of field conditions related to fracturing, lithology, drainage, topography, and rainfall, on the one hand, and on water yields in 81 drilling points made in fractured terrains on the other. The potentiality values given by the GPI81 map in the field checking area are compared with the water flows observed in 11 corresponding drill points. A significant correlation coefficient (r = 0.749) is found. The current results reinforce the previous ones on the fractured aquifer of Central Morocco and encourage the adoption of the GPI-based approach elsewhere. [ABSTRACT FROM AUTHOR]

The water supply needs of the city of Oaxaca have increased considerably over the last twenty years. The aquifer that produces 80% of the total water in the region is located in the Valley of Etla, to the NW of the city. Intensive exploitation of the aquifer has reduced the water quality. Basin geometry was estimated from 2.5-D models along four profiles, three W-E and one N-W. The sedimentary thickness reaches up to 730 m. Gravity and geologic interpretations suggest that the Mesozoic mylonites of the Sierra de Juárez and the metamorphic rocks of the Sierra de Oaxaca underlie the sedimentary infill. The fault pattern controls the tectonic behavior of the region and groundwater circulation. The Valley of Etla is a steep graben bounded by the Etla and Oaxaca faults. The main aquifers are in the Tertiary and Quaternary horizons. Twenty-three Vertical Electrical Soundings (VES) across the central part of the valley yield a thickness of the first aquifer of 20 m to 50 m. Wells in the area were used to control the resistive horizons and the stratigraphy. Electric tomography studies in the southern portion of the valley showed the base of the first aquifer at 50 m depth. The water-bearing sedimentary layers increase in thickness to the north of the valley, following the basement. Electromagnetic measurements reveal a vadose zone of at least 20 m thickness towards the center of the Valley. Zones of low resistivity were found in the northern and southern sections of the Valley. A possible contamination is suggested towards the northern portion of the City of Oaxaca.

Quantification of groundwater resources is indispensable for developing an efficient strategy for sustainable groundwater management. Integration of remote sensing (RS) and geographical information system (GIS) techniques with multicriteria decision analysis (MCDA) has emerged as a powerful tool for the economical and rapid assessment of groundwater resources at a macroscale. The main intent of this study is to evaluate the performance of two GIS-based approaches, namely MCDA as Approach I and probabilistic modeling as Approach II for groundwater prospecting. In Approach I, the thematic layers and their features relevant to groundwater prospect were extracted using RS and GIS, and appropriate weightages were assigned to individual layers and their features based on the analytic hierarchy process (AHP) scale. After the normalization of these weights, the selected thematic layers were integrated in the GIS environment to generate a groundwater prospect map. In Approach II, two probabilistic models, viz. frequency ratio (FR) and weight of evidence (WOE), were used. The FR and WOE probability values were calculated for each of the selected themes and then groundwater prospect maps were generated by overlaying the themes in GIS. The groundwater prospect maps thus obtained by the two approaches were classified into four distinct groundwater potential zones. These maps were verified using the available well-yield data. The verification results indicated that out of the AHP, FR and WOE techniques, the AHP technique is superior (prediction accuracy of 77 %) to the probabilistic models (FR and WOE), though the WOE model also performed reasonably well with a prediction accuracy of 73 %. It is concluded that for more reliable results, the AHP technique can be used for assessing groundwater potential in a given area/region. The findings of this study are useful for the cost-effective identification of suitable well locations as well as for the efficient planning and development of groundwater resources. [ABSTRACT FROM AUTHOR]

This paper describes pilot experiments to assess the potential of nuclear magnetic resonance (NMR) sounding and inversion for detecting groundwater at several sites in built-up, industrial and intensively cultivated regions in England where it is difficult to deploy large transmitter loops. The targets represent near-surface (ca. 1 m below the surface) and deep (>30 m) aquiferous (chalk, sand and gravel) deposits. The NUMIS field system was used in all the experiments and has infield processing and regularised one-dimensional (1D) inversion capabilities. All the sites were characterised by high noise levels and NMR depth soundings could only be effected using a small figure-of-eight loop for which the maximum depth of investigation was approximately 40–50 m. For comparison, conventional inductive and galvanic resistivity depth soundings were performed at these sites and the data have been inverted to yield the respective subsurface resistivity distributions.At two sites with shallow water levels, the location of the water deduced from inversion of NMR data corresponded with the water level measured in the nearby boreholes. For the site where the data quality is highest, the inverted profile of decay constants also corresponded with the known geology and the geoelectrical model. The NMR data from the other five sites are noisy and it is difficult to ascertain what aspects of the inversion models are correlatable to geoelectrical and geological data. The geoelectrical inversion results correlate with lithological and fluid content variations in the subsurface. It would appear that surface NMR (SNMR) sounding with figure-of-eight loop may be effective only when the ambient noise is less than 900 nV in the UK setting. [Copyright &y& Elsevier]

In crosswell observation of electromagnetic tomography, now there is no feasible way to calibrate the in-situ radiation constant, while the effect of induced wave-field always exists in observational data. Therefore the absorption coefficient obtained by a common-used image reconstruction method is only a relative value. The consistency of tomograms in linked profiles inevitably is affected seriously. An improved equation involving the effect of induced wave-field and an alternative tracing method to calculate the in-situ radiation constant is proposed in the present paper. Based on the results from a series of parameter calibration performed in water and the experiments with rock samples, the standard meter readings of borehole electromagnetic systems, types EW-1 and JWQ-3, are accurately defined here. Additionally, frequency reduction and boundary smoothing of linked profiles are discussed. In research on groundwater prospecting in Tanggongta, Inner-Mongolia, we used the above mentioned method and obtained the tomograms of linked profiles with good consistency. The absorption coefficient in the tomogram are not only reasonable and reliable, but also coincided with the result from rock parameter measurement. The depth, extension direction and water-bearing structure of two aquifers were well detected. This result correctly guides hydrologic drilling there. [ABSTRACT FROM AUTHOR]

An abstract is presented for the article "Prospección de aguas subterráneas mediante lógica difusa en Luanda, Angola."