# Assessment of the use of rainfall generators for the development of flood risk maps

Funded by: VMM

Researcher: Willem Jan Vanhaute

Promotors: Niko Verhoest; Patrick Willems (KULeuven)

Begin date: 01/02/2012

End date: 31/01/2014

In order to make reliable flood risk maps, coupled hydrologic-hydraulic models are used to predict the chance of flooding at different locations on and along a river system. However, such modelling requires long time series of rainfall and corresponding evapotranspiration rates (>500 year) which are not available from measurements. In this project, rainfall generators are tested and improved for their use in developing flood risk maps. Therefore, major attention is paid to the extreme behaviour of the rainfall time series and the ability of stochastic rainfall series to preserve the statistics of extreme discharges. Along with the improvement of the rainfall generators, a simple evapotranspiration model will be developed which will allow to generate time series of evapotranspiration values which are in agreement with the modelled rainfall.

The hydrologic model used to predict discharge values is the Probability Distributed Model (PDM). Although the VMM already has calibrated models for the different catchments in Flanders, a recalibration of these models will be performed in order to improve extreme discharge predictions. Furthermore, alternative models will be calibrated and the extreme behaviour statistics of discharge will be compared.

Finally, it will be assessed whether the use of rainfall generators for simulating long time series is beneficial for developing flood risk maps.