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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. [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]

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]