Comparative analysis of water quality from boreholes and shallow wells in ABU Zaria and its environs, Nigeria

Abstract

Groundwater is the cheapest source of drinking water in most developing countries including Nigeria. waste generated from industrial, commercial, agricultural and residential areas can seep into the soil through infiltration and gradually contaminate groundwater sources. This paper compared water from borehole and shallow wells in Ahmadu Bello University Zaria and it’s environs. Twenty-four (24) samples were obtained across the study area; out of this, eight were from the university main campus, eight from Hanwa community and eight from Tudun wada area. The parameters assessed include colour, odour, taste, pH, total hardness, dissolved oxygen (DO), total dissolved solids (TDS), chlorine (cl), nitrate, phosphate, lead (Pb), chromium (Cr), Iron (Fe), magnesium (Mg) and coliform count. Land use land cover (LULC) analysis was carried out using GIS techniques to determine the various land use across the study area. The result for LULC was used to assess the impact of each land use on groundwater quality. From the analysis of physico-chemical and bacteriological characteristics of groundwater within and outside the campus, it shows some levels of variability between borehole and shallow wells. Most borehole water from ABU (main campus) and Tudun Wada are slightly acidic while that of Hanwa had more places with pH values within the NSDWQ acceptable limit. For shallow wells, Tudun Wada area was found to be acidic in majority of the samples analyzed while ABU and Hanwa were within the normal range in most sample points. Other physico-chemical parameters such as TDS, hardness, Mg, Fe, Pb, and Cr were above the NSDWQ limits from both borehole and shallow wells across the study area. For the bacteriological analysis, it shows that shallow wells from ABU and Hanwa contains coliform above the NSDWQ limits while that of Tudun Wada contains no coliform. The presence of total coliforms in shallow wells from ABU and Hanwa means that shallow wells were more contaminated than boreholes across the study area. For the LULC analysis, it shows that cultivation is the dominant land use in areas within ABU. Hanwa is dominated by bare surfaces followed by farm lands; the major LULC in Tudun Wada is built up areas. It was also established that there is a strong relationship between groundwater quality and land use across the study area. The study concludes that groundwater across the study area is not safe for direct consumption because none of the water samples analyzed that complied fully with the NSDWQ standard. Appropriate water treatment techniques such as boiling, addition of lime, chlorination and filtration are recommended prior to domestic usage. This will help to reduce the spread of water borne diseases.