Empirical Estimation of the Effects of Climate Change on Drainage Sections

Abstract

Variability in climate change has compromised the design capacity of drains. Proper estimation of climate impacts on runoff is therefore necessary for the design of efficient and effective hydrologic sections. In this study, drainage sections were designed by incorporating climate-induced changes in runoff after quantifying the changes in annual runoff due to climate variability. The variability in each meteorological variable was used to estimate the climate-induced changes in the annual runoff. This approach was applied in some river basins in Southeast Nigeria and the highest change of 1.68 m³/s annual runoff: was observed in the River Adada in Enugu State, and 0.04 m³/s in Otamiri River, Imo State. It was also observed that climate change did not significantly affect the drainage sections in Abakiliki and Umuahia although only hte drainage width increased by 0.1% in Awka. There was a very significant change of 7% in the dimensions of the drain located in Adada watershed, Enugu while in the Otamiri river basin, Owerri, 0.2%change in the drainage capacity was estimated. It is evident that this study highlights the need for incorporating the excess climate-induced runoff volumes caused by climate change, in the design of efficient and safe hydrologic structures.