Abstract:
Study region: Terrain and hydrological data are scarce in many African countries. The coarsespatial resolution of freely available Shuttle Radar Topographic Mission elevation data andthe absence of flow gauges on flood-prone reaches, such as the Oti River studied here, makeflood inundation modelling challenging in West Africa.Study focus: A flood modelling approach is developed here to simulate flood extent in datascarce regions. The methodology is based on a calibrated, distributed hydrological modelfor the whole basin to simulate the input discharges for a hydraulic model which is used topredict the flood extent for a 140 km reach of the Oti River.New hydrological insight for the region: Good hydrological model calibration (Nash Sut-cliffe coefficient: 0.87) and validation (Nash Sutcliffe coefficient: 0.94) results demonstratethat even with coarse scale (5 km) input data, it is possible to simulate the discharge alongthis region’s rivers, and importantly with a distributed model, derive model flows at anyungauged location within basin. With a lack of surveyed channel bathymetry, modellingthe flood was only possible with a parametrized sub-grid hydraulic model. Flood model fitresults relative to the observed 2007 flood extent and extensive sensitivity testing showsthat this fit (64%) is likely to be as good as is possible for this region, given the coarsenessof the terrain digital elevation model.
Description:
A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use and the Universite Abomey Calavi, Cotonou, Benin, in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Climate Change and Water Resources
