GEOLOGY AND HYDROGEOLOGICAL ASSESSMENT OF UMUAWULU AND ITS ENVIRONS, AWKA SOUTH LOCAL GOVERNMENT AREA, ANAMBRA STATE.

This study presents a comprehensive geological and hydrogeological assessment of Umuawulu and its environs, located in Awka South LGA of Anambra State, Southeastern Nigeria. The area is underlain predominantly by the Nanka Formation, a member of the Eocene-aged Ameki Group, characterized by friable sands, silty shales, and minor clay beds. The research aimed to map the geological formations, evaluate groundwater potential using Vertical Electrical Sounding (VES), assess soil geotechnical properties, and analyze water quality across the region. A multidisciplinary approach was adopted, combining desk study, field mapping, geophysical survey, and laboratory analysis. Six VES profiles delineated 5 to 7 geoelectric layers, with groundwater depths ranging from 65 to 120 meters. Lithologic interpretation indicated aquifers composed mainly of water-saturated sandstones and silty shales. Laboratory tests, including Atterberg limits and particle size distribution, showed that most soil samples are poorly graded with low plasticity, indicating high susceptibility to erosion and poor engineering behavior. Water quality analysis revealed that most physicochemical parameters were within WHO (2019) limits. However, lead exceeded the permissible limit in 40% of samples, mercury in 70%, and cadmium in 50%, indicating significant trace metal contamination requiring urgent monitoring. Hydrochemical analysis using Piper and Durov diagrams classified groundwater in the study area as predominantly Ca–Mg–HCO₃ and Na–Cl water types, reflecting mixed recharge sources and possible anthropogenic influences. The findings underscore the need for erosion control, regular groundwater monitoring, and environmentally-informed land use planning in the area. This research provides a valuable baseline for future studies and development initiatives in Southeastern Nigeria.