Analysis and Interpretation of Lineaments for Evaluation of Groundwater Potential in Shendam and Environs, North Central Nigeria

This study was done to evaluate the groundwater potentials of Shendam and environs using lineaments analysis. The trends of field joints were measured during mapping and using satellite remote sensing to generate lineament. The area is underlain by crystalline basement rocks of biotite granite, medium grain granite, and syenite. Assessment was carried out to depict the possibility of groundwater occurrence in the area. LANDSAT ETM+ imagery was used, together with the geological map to investigate areas favorable for groundwater development. This was achieved by plotting the lineament trends, superimposing the lineament on the geological map, superimposing the lineament on the drainage map, furthermore by plotting density map to know the groundwater potentials of the area. Lineament was used in drawing the respective rose diagrams for each rock type. Structurally, the area is characterized by a predominant NE to SW trend which also affects or controls drainage and groundwater occurrence with major groundwater recharge areas trending NE- SW of the study area. Analyses have shown that the study area has numerous fractures whose major trends are mainly in NE-SW directions. Lineament density maps shows the cross-cutting lineaments to be relatively high in the areas around the northeastern to southwestern parts of the study area but low in the other areas. Zones of high lineament intersection density are feasible zones for groundwater prospecting.

Multisource data integration for groundwater prospecting in Precambrian shear zones, Espírito Santo State (Southeastern Brazil)

The Precambrian metamorphic rocks in the southern region of the Espírito Santo State(southeastern Brazil) is intercepted by ductile and brittle/ductile shear zones over which towns like Guaçuí, Marechal Floriano and Domingos Martins were established. In the years of 2014 to 2016 the Espírito Santo State faced the worst drought in the past 80 years. In situations like that, the only source of fresh water available is underground. Therefore, the purpose of this study was to integrate multisource data for groundwater prospecting and management. The study area comprises the central sectors of the Guaçuí and Batatal shear zones. Methodology involved the interpretation of stereo-pairs for the identification of lineaments, electrical resistivity surveys and geological fieldwork. The results were tentatively validated with available groundwater well production data. Six resistivity profiles with a total length of 2,400 m were surveyed and 15 outcrops were described across these structures. Results have shown that the structural framework of the shear zones is predominantly made of NW to NNW and NE to NNE-trending lineaments. The former is related to brittle tectonics and the latter coincides with the ductile Precambrian fabric of the crystalline basement rocks. A near-surface porous aquifer regarded to the regolith and recent unconsolidated sedimentary deposits presenting resistivity values < 1,372 Ohm.m and depths < 30 m have good potential for groundwater storage. However, results arenot conclusive about the hydrogeological significance of tectonic structures for groundwaterprospection in the study area.

Groundwater prospecting using the dipole-dipole configuration for vertical electrical sounding: prediction of major aquifer depth in the Tolon-Kumbungu district of Northern Ghana

A geophysical investigation in groundwater prospecting, using the vertical electrical sounding (VES) method in resistivity surveying, was undertaken in the Tolon-Kumbungu district of Northern Ghana. The aim was to evaluate the effectiveness of the VES technique as a low-cost groundwater exploration method. Using the dipole-dipole VES technique, fracture zones that held good prospects for groundwater location were prospectively identified at 15 sites in the Gbullung and Wayamba communities of the district. In addition, retrospective VES data for 6 sites were obtained from previous studies. Geophysical VES data and available drill logs for 3 sites in the prospective study and all 6 sites in the retrospective study (a total of 9 sites) were then evaluated by the VES log-log graph interpretation method to establish a correlation with the groundwater characteristics of the study area. The analyses of the VES curves indicated the presence of anomalous fracture zones occurring within hard sandstone formations that had high groundwater potential. Weathered zones or fresh rock aquifers however did not show potential for groundwater. The dominant formations in the area were found to be thin-bedded sequences of sandstone, mudstone, shale, siltstone and their intercalations. Groundwater was confined to between the depths of 25.0 m and 40.0 m, with major aquifers occurring approximately between the depths of 34.0 m and 45.0 m. These predictions were confirmed by the available drill logs. Using the VES curve interpretation as a means of selecting promising water-bearing sites, 8 out of the 9 sites drilled were successful wells, recording water yields ranging from 14 L/min to 250 L/min, with an average yield of 87.3 L/min. The study thus showed that the dipole-dipole VES technique in groundwater prospecting is effective for the geology of the study area. Keywords: Tolon-Kumbungu; vertical electrical sounding; aquifer; groundwater; apparent resistivity