Applied Water Science (Jan 2020)
Eco-hydrology and the effects on the national economy: case of the eastern region of Abakaliki Anticlinorium, Southeastern Nigeria
Abstract
Abstract The area was mineralized, yet it is an agricultural settlement. Histories of water hardness and local migration of connate (saline) water exist across the region. This study investigated effects of these geogenic circumstances on the economy of the region and Nigeria. Geophysical and geochemical analyses were carried out for delineation of hydrological structures relevant to groundwater movement and pollution status, respectively. Results revealed silty–sandy shale sandwiched between 60 and 100 Ω-m at the fourth geoelectric layer. This layer marks depths to water table from 7.0 to 12.0 m and formed aquitard as medium of regional stance for groundwater percolation. The aquitards confined localized resistivity anomalies of ≤ 60 Ω-m and was interpreted as various aquifers. Isolated peaks of hydraulic head up to 85 m around north-western and south-eastern ends of NW–SE-trending local water divide indicated areas of water table crops where conjunctive hydrological interaction exists between surface water and groundwater resources; each flushes dissolved elements from the calcareous sediments into the water resources. Consequently, configurations of pH, total dissolved solutes (TDS), electrical conductivity (EC) and total hardness ranged as: 6.97–7.96, 20–1399 mg/l, 30–2100 μs/cm and 8–160 mg/l, respectively. Localized concentrations of calcium, sodium, bicarbonate, sulphate, chloride, iron, manganese, zinc, lead, chromium and cobalt in mg/l ranged to pollution or alert levels as follows: 38–590, 5–89, 10–126, 30–460, 6–128, 0.01–1.74, 0.1–0.41, 0.001–0.13, 0/01–1.98, 0.011–0.56 and 0.05–0.22, respectively. The water is therefore hard and hence supports encrustations of fittings for water supplies. Consequently, screens’ slot sizes were clogged, resulting in incessant boreholes failures in the region. Heavy metals are polluting from identifiable loading sources, possibly, due to the proximity of associated lodes. These pollution(s) caused the exceedance of TDS (as reflected in EC) above the saline borderline and hence the salinity and sodium hazards that hampered crop growth, mainly cereal foods. It also endangered biodiversity of adjoining downstream regions.
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