Managing High Runoff Discharge in the Urbanized Basins of Asa River Catchment Area of Ilorin, Nigeria

Abstract

Incidence of flood has been on the increase in Ilorin for sometime; and this exemplifies the problem operating in most urban centres in Nigeria. Increase in runoff production in an urbanized catchment is a function, among other factors of to increase in percentage paved area brought about by deforestation activities and poor environmental attitude of the people. This study examines the relationship between runoff discharge and basin characteristics in Ilorin. Data used were collected directly from the field over a period of one calendar year. Rainfall data were collected in each basin using a standard rainguage of 20cm orifice while basin discharge was collected twice daily (8.00am and 6.30pm) using fabricated staff gauge graduated in centimeter. Basin morphometric attributes were computed from topographic map while landuse map was prepared from satellite imagery. Soil samples were collected and analysed for particle size distribution. The result obtained indicates that basin size and landuse have profound influence on the explanation of discharge in the basins. The study thus, recommends a number of options to efficient basin management in the city. Keywords: Managing; High runoff discharge; Urbanized basin; Asa river catchment; Ilorin; Nigeria