A study that assess the performance of the HBV hydrological model to simulate flash floods and to identify not-reported flash floods in the Ourthe basin.
Flash floods in the Ourthe basin: performance of the spatially distributed HBV model
Flash flood events are one of the most important natural hazards in Europe. Flash floods are often characterized by rapid water rise and short responds times prohibiting adequate measures. The 2008 flash flood in Sart Tilman alerted the Belgium authorities and scientists of flash flood risks in low mountainous areas. This study gathers additional insights in the skills of the HBV hydrological model with respect to flash flood modelling in a low mountainous catchment. The HBV hydrological model was already applied to simulate flash floods, but an extensive evaluation on the performance during flash floods was lacking. Therefore this study aims to assess model performance to simulate flash floods and to identify not-reported flash floods. Multiple techniques were applied, i.e. the index flood method and the particle swarm optimization.
Area of interest was the Ourthe catchment, a low mountainous catchment in the Belgium Ardennes. The Ourthe catchment is a rain fed and fast responding system. In combination with the geological conditions, the area is prone to flash floods. Therefore the area was suited to test the HBV hydrological model extensively for flash flood simulation.
The HBV hydrological model is commonly used conceptual model with many different applications. This study showed that the HBV-96 hydrological model was not able to simulate both a flash flood triggered by high precipitation intensities and the normal hydrological regime with the same set of parameters. Therefore the model structure was adjusted based on other studies. The most important modification was the implementation of a threshold function in the upper zone storage reservoir. The results of this study showed that the new model structure was able to simulate both a flash flood and the normal hydrological regime of the Ourthe catchment with the same set of parameters. The study showed a good performance of the spatially distributed HBV hydrological model to simulate flash floods and the normal hydrological regime with the same set of parameters.