Medium Ranged Flood Forecasting For Upper Baro Akobo River Basin Testing The Applicability Of European Flood Alert System (efas) Methodologies To African Small - Medium Scale River Basins.

Flooding has always been a critical and common disaster in Ethiopia taking the lives of many people andrnlivestock, displaced millions and destroyed a huge amount of the economy. The Baro-Akobo river basin -rna trans-national river basin in Ethiopia located between latitudes of 5 ° 31` and 10 ° 54` N, and longitudesrnof 33 ° and 36 ° 17` E with an altitude range from 402m to 3106m - is one of the flood prone areas in therncountry which have been hit by different floods. In every rainy season news on floods in most of the riverrnbasins in the country is very common. Thus, establishing flood forecasting and early warning systems tornthe basin and the country as well is important. rnIn this paper, the methods of the European Flood Alert System (EFAS) are tested and adapted. EFAS is arnmedium range system to provide warning for flood hazards in European transnational rivers 3-10 days inrnadvance of the floods. The LISFLOOD GIS based distributed hydrological model - underlying the EFASrnsystem – was used with precipitation products from five different sources: TRMM (Tropical RainfallrnMeasuring Mission product of NASA), PRESSIAN (Precipitation Estimation from Remotely SensedrnInformation using Artificial Neural Networks product of University of Arizona), RFE (African RainfallrnEstimation Algorism product of National Oceanic and Atmospheric Administration - climate predictionrncenter ), ERA-interim (product of European Center of Medium-Range Weather Forecasts (ECMWF’s)rnand observed precipitation (interpolated by invers distance method). rnLong time observed discharge data from the Ethiopian Minister of Water Resource and Energy were usedrnfor model calibration and verification. Additional input data are collected from 15 observedrnmeteorological stations data around and in the basin from Ethiopian National Meteorology Agency, staticrndata sets such as elevation data, leaf area index, soil data, land cover and others, and satellite precipitationrndata from Joint Research Centre (JRC) which were mapped for the African continent at 0.1rnorngrid scale. rnThe model was calibrated using the SCE-UA (genetically adaptive approach for effective and efficientrnglobal optimization) algorithm. Both calibration and validation resulted in good scores for most rnprecipitation datasets. Hindcasting results using ECMWF weather forecast data indicated that the EFASrnmethod is capable to forecast small floods. Typical EFAS thresholds used in Europe need to be adjustedrnto allow for sending alerts already for smaller floods (return periods of 1 year). Hindcasting with adjustedrnthresholds yielded sound results and demonstrated the applicability of the system.

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