Assessing River Benue flow data for flood mitigation and management in Adamawa catchment, Nigeria

Abstract

Information on the historical patterns, seasonal variation of river flows, and flood frequency necessary for flood mitigation in the Adamawa catchment are limited. In this study, river flow and water stage time series for stations within River Benue reaches were analysed and peak flows were computed using the Weibull formula. The stage time series was decomposed to extract cycles and trends using the classical multiplicative (CM) model. Subsequently, spectral analysis was performed for periodogram/spectrum comparison of actual and fitted values from the decomposition modelling. The findings show that the peak flows for 10-year, 25-year, 50-year, and 100-year designed flood for the stations exceed the danger level at Jimeta and Numan. Moreover, water heights of 6.3 m (∼3400 m3/s for Jimeta) and 9.3 m (∼4800 m3/s for Numan) were observed. The implication when compared to the designed flood discharge for different return periods is that there will be increased flooding in the catchment. CM modelling accuracy showed that the root mean square error was 0.8114 cm (Jimeta), 0.0160 cm (Ngurore West), and 0.0004 cm (Dong) with R2 not below 98% in each case. A deep-climax pattern that indicates seasonality was observed, and the seasonal variation is believed to be the result of changing weather.

Keywords

• Adamawa catchment
• River Benue
• Flood modelling
• Classical multiplicative model
• Nigeria