Impact of different land use types on groundwater quality in Ibadan, Nigeria

Abstract

Studies of comparative analysis of groundwater quality under different land use types are scarce, and such studies remain critical in achieving sustainable water resource management. This study used suitable multi-statistical techniques alongside the Water Quality Index (WQI) to assess and compare the effects of residential, industrial, and agricultural land use types on groundwater quality in a region of Ibadan, Nigeria, primarily underlain by banded gneisses. The study also established the appropriateness of the water samples for human consumption. Thirty water samples, consisting of 10 samples each from three different land use types, were randomly collected and subjected to established methods of analysis for nine physicochemical parameters. The results from the Kruskal-Wallis test and Dunn's test showed that average concentration levels of pH, total hardness, calcium, magnesium, chloride, bicarbonate, nitrate, and sulfate in the tested water samples were significantly different (p-value ≤ 0.05) among the three land use types investigated. The results also suggested that where poor environmental conditions are common, residential land use type could pose a greater risk to groundwater quality than either agricultural land use or industrial land use. At least, a three-factor model was suggested and explained 63.4 %, 70.2 %, and 91.6 % of the total groundwater quality variation under the residential, agricultural, and industrial land uses respectively using Kaiser's varimax rotation method. In addition, the WQI results showed that 100 % of the water samples from industrial and agricultural land uses were appropriate for drinking but only 20 % of the water samples from residential land use were. The findings indicated that differing land use types affect groundwater quality in different ways. It was thus recommended that an improved sanitation system should be provided by the authorities to help reduce groundwater pollution in the residential area. This can help toward achieving water security mentioned in the African Union's Agenda 2063.