Ghana

Uganda

Burkina Faso

Application of satellite rainfall estimation to flood early warning systems

• Satellite-based rainfall estimation (rfe) algorithms could potentially provide real time data on extreme rainfall events that could be utilised for flood early warning systems in Africa.

• Grimes & Diop ’03 studied the feasibility of using satellite rainfall estimates as input to a simple rainfall-runoff hydrological model, in order to forecast river flows. They used the Bakoye catchment area in Mali as a test case. The approach showed some skill at predicting river flow, but without contemporaneous gauge data for calibration (rare in Africa) it was not accurate enough to be useful operationally.

• Algorithms based on Cold Cloud Duration such as TAMSAT are statistical in nature, and need to be averaged over sufficiently large time and/or space scales to produce accurate estimates. For river flow forecasting time scales need to be of the order of a day or less, so the corresponding space scales must be an area of several thousand km squared. Therefore this approach is limited to medium to large river basins.