IMPACT OF URBAN LAND USE ON RAINWATER QUALITY: CASE STUDY IN ILORIN METROPOLIS, NIGERIA

Abstract

In Ilorin being one of the fastest growing urban centres in Nigeria, the physical transformation in land use and population density have effects on the rainwater quality. Therefore, we aimed to analyse the relationship between physical and chemical properties of rainwater and urban land uses. A total of 15 rainwater samples were collected after two major rainfall events with an average duration of 20 minutes during the rainy season and analysed for 15 physical and chemical parameters namely: colour, conductivity, pH, total dissolved solids, turbidity, aluminium (Al3+), copper (Cu2+), iron (Fe2+), nitrate (NO3- ), lead (Pb2+), nickel (Ni), sodium (Na+ ), phosphorus (K+ ), zinc (Zn2+) and sulphate (SO4 2- ). Their mean, standard deviation, coefficient of variation, Pearson correlation coefficient were used to interpret the results. The land use types in the area were agricultural, commercial, industrial, institutional and residential. The result revealed that the urban land uses and rainwater quality has a significant relationship in Ilorin Metropolis. Agricultural, industrial and institutional land uses had the least significant effect on the quality of rainwater with the significant value (P<0.05) of 0.044, 0.035 and 0.014 respectively. In contrary, under residential land use the rainwater had poor quality (significant value: 0.724), while under commercial land use the rainwater had fairly good quality (0.585; P>0.05). The study concluded that the urban land uses has an impact on the rainwater quality. The study recommends that rainwater should be purified before drinking, and sustainable urbanization policies should be developed to prevent atmospheric pollution in Ilorin Metropolis.