In this comprehensive study, we delve into the chemical properties of soil in the proximity of sinkholes located in Anambra state of Nigeria. Three distinct sinkhole sites were selected for examination: Awka site 1 (6.2232°N and 7.0824°E), Awka site 2 (6.2220°N and 7.0819°E), and Agulu (6.0941°N and 7.0203°E). For a comprehensive analysis, 24 soil samples were meticulously collected and subjected to thorough analysis. These samples comprised of 15 specimens obtained from the immediate vicinity of the sinkholes, while 9 samples were procured from locations situated at least 2 kilometers away from the sinkhole sites. The study focused on investigating various parameters, namely pH levels, Organic Carbon (OC) content, Organic Matter (OM) content, Aluminum (Al) levels, Hydrogen (H) levels, Total Nitrogen (TN) content, Magnesium (Mg) levels, Potassium (K) levels, Sodium (Na) levels, Calcium (Ca) levels, Effective Cation Exchange Capacity (ECEC), Base Saturation, and soil texture. The obtained results revealed that the study areas predominantly exhibited a sandy composition with a notably low clay content. Furthermore, the analysis indicated low hydrogen values, while sodium levels were observed to be relatively high. Consequently, certain areas, particularly those situated farther away from the sinkhole site, exhibited a reduced amount of exchangeable bases and effective cation exchange capacity. This phenomenon potentially resulted in leaching and dispersion within the soil, leading to inadequate water infiltration and subsequent run-off. Notably, this process may have contributed to the formation of tunnel erosion, ultimately resulting in the emergence of sinkholes.

The research focused on evaluating the groundwater potential in the vicinity of Federal University of Technology Owerri (FUTO) using a resistivity survey method. The investigation involved the utilization of eleven Schlumberger vertical electrical soundings (VES). The data collection was conducted using an ABEM Terrameter SAS4000 and then processed with IPI2Win Software, which relies on the conventional theory of curve matching. This process aimed to determine the depth, quality, and subsurface formations of the groundwater. The VES interpretation results revealed the presence of 3-5 geoelectric layers above the aquiferous layers. Various curve types were identified in the study area, including monotonically ascending (AA), bowed-ascending (HA), bowl-bell (HK), and ascending-bell (AK) curves. The majority of the field curves were found to be of the A-shaped type, signifying specific aquifer characteristics. The study indicated that the depth to the water table is relatively shallow in the Ihiagwa area, with an average depth of 7.26 meters. In contrast, the aquifer's depth is deeper around Avu, Nekede, and Eziobodo areas, with a mean depth of 32.33 meters. Obinze had very deep aquifers, with an average depth of 57.75 meters. Furthermore, the study established a relationship between aquifer characteristics and geoelectric parameters, allowing for the estimation of hydraulic conductivity and transmissivity values at all the sounding locations, even in areas lacking boreholes. These hydraulic characteristics showed that the aquifer had protective capacities ranging from 0.036 to 0.509 mhos, transmissivity values ranging from 11856.32 to 28661.28 m2/day, and hydraulic conductivity ranging from 13.47 to 1009.2 m/day. These values suggested that the aquifer materials are highly permeable, facilitating fluid movement within the aquifer. This research demonstrated the effectiveness of surface geophysics in estimating aquifer hydraulic characteristics, particularly in situations where pumping test data are unavailable. It also highlighted the vulnerability of the aquifer to surface contaminants. The findings are expected to be valuable for the long-term planning of groundwater exploitation projects in the study area.