Assessing the Impact of Urbanization on Groundwater Resources in Selected Areas of Minna Metropolis, North-Central Nigeria.
Abstract:
A comprehensive study was conducted to investigate the geology and hydrogeology of a portion of Minna Sheet 164NE with the objective of assessing groundwater potential and control mechanisms. The study area encompasses Minna, located between longitude 6°30′E and 6°32′E, and latitude 9°37′36′′ N and 9°39′34.5′′ N, covering an area of 14 km2. This region supports a substantial population heavily reliant on groundwater for domestic purposes. The geological survey, carried out on a scale of 112,000, involved the traverse method to establish the structural disposition of outcrops, along with subsequent thin section analysis of representative rock samples using a petrological microscope.
The groundwater inventory included the documentation of well locations, borehole depths, water levels, and yield. Samples of the water were collected and subjected to physical and chemical analyses. The geological composition revealed that approximately 90% of the area is underlain by rocks belonging to the older granite suite of the Nigerian Basement complex system, while the remaining 10% is underlain by schist. The predominant joint direction was identified as NNE-SSW. The weathered rock thickness ranged from 5 to 10 meters, and the wells had an average depth of 5 meters with a water level at 3.57 meters. Boreholes, on the other hand, had an average depth of 134 meters and a mean yield of 71.28 m3/d (0.83 L/s).
The groundwater potential map indicated that the north-eastern part of the area possessed higher potential at shallow levels, while other regions exhibited slightly lower potential. The overall regional groundwater flow direction was observed to be in the NE-SW direction. The analysis of water samples revealed that the groundwater had an average pH of 7.3, Electrical Conductivity (EC) of 637.5 µS/cm, and a temperature of 28.6°C. Noteworthy parameters with higher concentration included chloride at 82.35 mg/l, bicarbonate at 70.18 mg/l, sodium at 56.18 mg/l, calcium at 46.16 mg/l, and nitrate. Additionally, certain trace elements were found to occur at fairly high concentrations, such as zinc at 1.15 mg/l, phosphate at 0.81 mg/l, and fluoride at 0.32 mg/l.
Based on their concentration levels, the water was primarily classified as mixed calcium-magnesium-chloride water and secondarily as sodium-bicarbonate water. Furthermore, the presence of heavy metals in the groundwater warranted their categorization as Potentially Toxic Elements (PTEs).
Assessing the Impact of Urbanization on Groundwater Resources in Selected Areas of Minna Metropolis, North-Central Nigeria.