Spatial dependency of groundwater quality in Benin City, Edo State, Nigeria using semi-variogram models

Abstract

Water quality is a worldwide concern especially water for human consumption. Regular monitoring and tools should be developed, to ensure continuous assessment of the level of concentration of chemical constituents prevalent in water. This will guide against health dangers and risks associated with water of low quality. The research focus on using semi-variogram models to measure the degree of spatial dependency of sampled boreholes for prediction of the concentration of water quality parameters at un-sampled locations because of the cumbersome nature of assessing the whole boreholes in Benin City. One hundred and ten (110) different domestic boreholes were systematically sampled and analyzed in laboratory for determination of the concentration of some chemical water quality parameters which include Electrical Conductivity (EC), Total Dissolve Solids (TDS), Bicarbonate (HCO3), Sodium (Na), Potassium (K), Calcium (Ca), Magnesium (Mg), etc. Laboratory examination of boreholes water quality parameters were carried out in wet and dry seasons. Geographical locations of sampled boreholes were also determined. The obtained experimental results were utilized in investigating the spatial structure of the boreholes using semi-variogram models which include spherical, exponential, Gaussian etc. Exponential model was the most fitted model. The borehole water quality parameters exhibited high degree of spatial dependency in EC, TDS, HCO3, Na, K, Ca. Mg, Cl, P, and NO3 in both seasons with ratio < 25% therefore, interpolation technique can be employed to produce spatial variation quality map of boreholes in Benin City as a monitoring technique to detect contamination or changes in water quality.

Entropy-Weighted Water Quality Index Assessment of Groundwater in Ibadan Metropolis, Nigeria

“…Other modern groundwater quality evaluation tools include systemic entropy and ionic spatial distribution GIS analyses (Adimalla, 2021;Adimalla et al, 2020;Feng et al, 2019;Gao et al, 2020;Gorgij et al, 2017;Islam et al, 2020;Sahoo et al, 2017;Subba Rao et al, 2020;Ukah et al, 2020). Notably, many initiatives have been taken by scientists in Nigeria to assess groundwater quality for domestic use using different approaches such as the WQI system (Balogun et al, 2012;Olatunji et al, 2015;Kwami et al, 2018;Olasoji et al, 2019;Ekere et al, 2019;Bamigboye et al, 2020;Ishaku et al, 2020), GIS modelling (Edet, 2014;Karo et al, 2019;Nwankwoala et al, 2012;Ogunbode and Ifabiyi, 2017;Oyedele, 2019;Oyedele et al, 2019), and statistical multivariate analysis (Amah and Agu, 2020;Ayuba et al, 2013;Egbueri, 2019;Ezugwu and Atikpo, 2021;Kwami et al, 2018;Okiongbo and Douglas, 2015).…”