A floodplain storage model used to determine evaporation losses in the Upper Yobe River, northern Nigeria

Abstract

River flow losses in the Upper Yobe River are ∼70% of the total annual runoff. The annual flow regime is seasonal with widespread flooding in the lowlands and the storage effect causes flooding to continue into the dry season when potential evaporation is a maximum. The open-water and swamp evaporation losses could not be calculated directly because of the lack of data on the area flooded which varies monthly and seasonally. A floodplain storage model is described which simulated the changes in the flooded area with time on a monthly basis for eleven years of record. Using this model, open-water and swamp evaporation losses were calculated to be ∼45% of the total runoff.