Analysis of the Impacts of Rainfall Variability on Public Water Supply in Ilorin, Nigeria

Abstract

Several studies have revealed the impacts of rainfall variability on water resources across the world. This paper makes an analysis of the impacts of rainfall variability on public water supply in Ilorin. The data used in this
study are mainly rainfall amount for 30 years (1981-2010), which was obtained from NIMET and the quantity of water supplied by Kwara State Water Corporation, which was only available for 11 years (2001-2011). These data were interpreted using both descriptive and analytical methods. The analytical procedures include time series analysis, reduction pattern analysis and Pearson moment correlation. The results of the trend analysis show that rainfall and water supply in Ilorin have been on the increase at the rate of 0.27mm per annum and 0.20 million (m3) per annum respectively over the period of study. The results of reduction pattern analysis carried out revealed the variability and the percentage changes in rainfall and water supply over time in Ilorin. The result of Pearson moment correlation coefficient revealed that strong negative relationship (-0.6) existed between monthly rainfall and monthly water supply at 0.05  significant level. This shows that as rainfall increases, water production in the treatment plant decreases. This is expected in view of the increasing cost of water treatment in rainy seasons. It was concluded that increase in
rainfall poses water treatment challenges. It was therefore recommended that the capacity of treatment plants be increased. This would enable proper management of the abundant surface water and in turn increase water supply in the city.

Keywords: Rainfall variability, public water, supply, trend