Investigation of groundwater vulnerability to open dumpsites and its potential risk using electrical resistivity and water analysis

Abstract

Understanding the impacts of open dumpsites and its implication on groundwater systems is a critical component of water security for sound long-term environmental management strategies. However, predicting the impacts of dynamic dumpsites on environmental systems is a difficult task that requires a technical approach. This paper applies electrical resistivity and physicochemical water analysis techniques to investigate the groundwater vulnerability to open dumpsite leachates and its potential environmental risk. A total of twenty-nine (29) vertical electrical sounding (VES) were acquired within and around the dumpsites. A physicochemical properties analysis of water from seven hand-dug wells (HDWs) within a 200 m radius of the dumpsite was performed. The subsoil resistivity values encountered within the dumpsite and off-dumpsite vary from 2.4 Ωm to 17 Ωm and 68 Ωm – 611 Ωm respectively. The study links up the subsurface geo-electrical properties (resistivities) with the physiochemical water analysis, which affirmed the electrical resistivity technique efficiency in dumpsite investigation. The geophysical and water analysis results indicate that the groundwater systems within and around the dumpsite are highly susceptible to dumpsite leachates and require urgent evacuation to avoid the impending risks posed to both human health and the environment. While the geophysical analysis indicates high leachates infiltrating index in the subsoil, which invariably affects the groundwater resources, the physicochemical analysis indicates a high concentration of heavy metals, COD, BOD, TDS and high electrical conductivity (EC), affirming the geophysical results. The leachate plumes of the dumpsite suggest to have masterminded the groundwater pollution, the high heavy metals dominating the 7 HDWs have significantly influenced the chemistry of the groundwater quality within the area. Thus, dumpsite is the major cause of groundwater pollution. Indications show that the impacts of dumpsite leachates decreased with depth and source distance. More also, groundwater systems within a 200 m radius of the dumpsite are at risk of a high vulnerability index. Besides the study indications, some influential regional factors such as climatic conditions, hydrology and geology of the dumpsites have further amplified the impending major environmental crisis. Consequently, the study suggests future environmental preservation for the future direction.