The 21st August 2020 Flood in Douala (Cameroon): A Major Urban Flood Investigated with 2D HEC-RAS Modeling
Junior Yves-Audrey Iroume,
Raphaël Onguéné,
Francis Djanna Koffi,
Antoine Colmet-Daage,
Thomas Stieglitz,
Willy Essoh Sone,
Sakaros Bogning,
Joseph Magloire Olinga Olinga,
Romaric Ntchantcho,
Jean-Claude Ntonga,
Jean-Jacques Braun,
Jean-Pierre Briquet,
Jacques Etame
Affiliations
Junior Yves-Audrey Iroume
Technology and Applied Science Laboratory, University Institute of Technology, University of Douala, Douala P.O. Box 8698, Cameroon
Raphaël Onguéné
Technology and Applied Science Laboratory, University Institute of Technology, University of Douala, Douala P.O. Box 8698, Cameroon
Francis Djanna Koffi
Technology and Applied Science Laboratory, University Institute of Technology, University of Douala, Douala P.O. Box 8698, Cameroon
Antoine Colmet-Daage
Philia Ingenierie, 193 Avenue Jean Rieux, 31500 Toulouse, France
Thomas Stieglitz
Aix-Marseille Université, CNRS, IRD, INRAE, Coll France, CEREGE, 13100 Aix-en-Provence, France
Willy Essoh Sone
Ecosystems and Fishery Resources Laboratory, Institute of Fisheries and Aquatic Sciences, University of Douala, Douala P.O. Box 2701, Cameroon
Sakaros Bogning
Institute of Geological and Mining Research, Vogt Street, Yaoundé P.O. Box 4110, Cameroon
Joseph Magloire Olinga Olinga
Douala Urban Council (DUC), Douala P.O. Box 1857, Cameroon
Romaric Ntchantcho
Institute of Geological and Mining Research, Vogt Street, Yaoundé P.O. Box 4110, Cameroon
Jean-Claude Ntonga
Institute of Geological and Mining Research, Vogt Street, Yaoundé P.O. Box 4110, Cameroon
Jean-Jacques Braun
Laboratoire Mixte International—Dynamique des Ecosystèmes Continentaux d’Afrique Centrale (LMI-DYCOFAC), Institut de Recherche pour le Développement, Yaoundé P.O. Box 1857, Cameroon
Jean-Pierre Briquet
HydroSciences Montpellier, Université de Montpellier, CNRS, IRD, 300 Av. Pr E. Jeanbrau, 34090 Montpellier, France
Jacques Etame
Technology and Applied Science Laboratory, University Institute of Technology, University of Douala, Douala P.O. Box 8698, Cameroon
A major flood event occurred on 21 August 2020 in the densely populated Makèpè Missokè neighborhood in the city of Douala (Cameroon, Africa). Nearly 2210 buildings and 12,376 victims spread over 82 hectares were affected. A 2D HEC-RAS model is applied to simulate and characterize this event. A cross analysis of flood depth and flow velocity is used to classify the flood risk and identify areas exposed from low to high hazard. The simulations provide detailed information on the flood characteristics (extent, depth, velocity, arrival time, and duration). The simulated maximum water surface profiles are consistent with the floods marks with differences ranging from 0.02 m to 0.44 m, indicating a good agreement between the observed and simulated water levels at the peak flow (NSE = 0.94, Erel = 0.92, RMSE = 0.21 m). The maximum inundation level is 4.48 m and the flow velocity is globally low at less than 1 m/s. The average flood arrival time and duration are 5 h and 26 h, respectively, for a threshold height of 0.5 m. These results indicate a fast mobilization of the major river channel for the evacuation of this flood. The level of accuracy of the developed model of the 21 August 2020 flood event is appropriate for flood hazard assessment in the city of Douala and is designed to find operational application in future events.