Water Budget Position and its Implications on Basin Management in Urbanized Catchment of a Tropical City in Ilorin, Nigeria

Abstract

The study investigates water budget position in Ilorin, Kwara State Nigeria using temperature and rainfall data collected from Nigerian Meteorological Agency (NIMET) at Ilorin International Airport for a period of ten years. From the temperature record, the evapotranspiration values were computed for the city using modified Thorntwaite (1948) formula. Water budget graph was subsequently posted using the rainfall and computed evapotranspiration data. Result obtained indicates that the month of September received the highest mean monthly rainfall while lower rainfall values were recorded in the months of January, February, November, and December. The mean monthly temperature was fairly constants throughout the year while evapo-transpiration values were generally high during the dry season. Water budget graph plotted indicates that soils in the study area were at deficits between of November and late April while significant water surplus condition was observed between May and October. The water surplus position in August was however observed to be relatively low. Reason for this may not be unconnected with the short dry spell condition which is usually experienced in the study area around this period. The study subsequently examined the implications of its findings on basin management within and around the city.