Rainfall andRunoff Relationship forDetermination ofWater Abstraction Potential ofRiver Osun, Southwestern, Nigeria

The hydrological regime is characterized by high variability of rainfall and runoff distribution. The hydrologist finds it difficult to make accurate prediction of water abstraction by various dams. Inspite that Osun is blessed with abundant water resources being one of the states that supplier water to resident in Osun state, water supply is made inadequate due to lack of schedule of water by facilities abstracting water from the river. In this study, the Rainfall-Runoff Relationship for Determination of Water Abstraction Potential of River Osun was investigated. The model developed was a linear regression approach considering effects of past rainfall on the runoff of the effluent streams. Forty (40) years rainfall data collected from 1974 – 2012 were used to estimate corresponding runoff using empirical approach. The rainfall were repressed against runoff and the corresponding runoff arrived at regression coefficient of 0.912 and 0.896 respectively. Generated runoff for River Osun were determined. The data could serve as a veritable hydrological input in the allocation of water for the dams abstracting water on the river. It is recommended that to find a lasting solution to the menacing frequent lack of water by dams abstracting water on River Osun