Impact of Selected Landuse Types on Surface Water Quality Downstream of Asa Dam in Kwara State, Nigeria

A. O. Ayeni
I. I. Balogun
O. A. Adeaga

DOI: 10.2190/ES.32.3.c


This study examines the impact of selected land use types on surface water quality downstream of Asa dam in Ilorin, Southwestern Nigeria. Water samples were collected at seven points (including a control, 0.50 km from Asa dam). Four-sampling points fall within agricultural land use area, two within light industrial/residential area, and the control was within an undisturbed natural environment. The level/concentration of 10 physico-chemical parameters, color, total dissolved solids, dissolved oxygen, biochemical oxygen demand, total hardness (CaCO3), calcium hardness, magnesium hardness, chloride, calcium, and nitrate were determined using standard procedures. GIS was used to determine the extent of land cover by Asa dam and its downstream environment including the length of River Asa in respect to sampling points. This was achieved through the map generated from satellite imageries and the use of GPS. This article presents and discusses the results of laboratory analyses undertaken, spatial variability in the level/concentration of the water quality parameters, as well as the consequences of sustained use of River Asa water without treatment for domestic purposes. The results show that the quality of River Asa downstream of the dam was impaired to different degrees using WHO standards for the selected parameters and land use types. Consequently, using the water for domestic purposes, in particular as currently obtained in the area, portends grave danger to human health and the situationwill be worse in the near future if necessary control is not put in place.

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