Item

Abstract

This study examines the spatial variation of the available water resources in relation to landscape morphology of the Ogun River Basin in Southwestern Nigeria. It made use of rapid water accounting plus (WA+) approach and satellite earth observation open access data from the Water Productivity (WaPOR) version 2.0. The satellite based data in combination with ground-based data were integrated in QGIS software environment to generate precipitation and evapotranspiration per relief unit and was used to determine the water balance per morphological unit area. Regression model was adopted to determine the relationship between precipitation, actual evapotranspiration and elevation. The results show that gently undulating plains and nearly level plains received the highest average precipitation of 1640.6 mm/year and 1623.42 mm/year respectively while undulating dissected plains received the lowest average precipitation of 1266.39 mm/year. Also, the highest evapotranspiration occurred in the Undulating plains with scattered rock outcrops and hills with an average annual value of 1209.2 mm/year and the lowest in the gently undulating plains with an average annual value of 669.55 mm/year. There is a low positive relationship of r² = 0.2179 and r² = 0.0742 between elevation and annual precipitation and between elevation and average annual evapotranspiration respectively. This suggests that rainfall distribution and rate of actual evapotranspiration are minimally influenced by elevation. Thus, in the face of climate change and dwindling economy, small scale water projects across the morphological units of Ogun River basin is recommended for sustainable multi-purpose water uses