Hydrologic modelling for surface water management – estimation of the catchment averaged evapotranspiration

Funded by: Ghent University
Personnel: Bruno Samain
Promotor: Valentijn Pauwels

An accurate understanding of the behavior of the different water and energy balance terms at the catchment scale is of interest for hydrologic modeling and operational flood forecasting. Flood forecast models are usually based on two different kinds of meteorological inputs, more specifically the catchment averaged precipitation and evapotranspiration rates. These are then related to the catchment discharge through a number of conceptual equations, of which the parameters are tuned through a comparison of the modeled discharge to observations.
The most difficult meteorological forcing to quantify is the catchment averaged evapotranspiration rate. More specifically, evapotranspiration rates are spatially very variable, are rather expensive to measure at small spatial scales, and up till present cannot be continuously observed at the catchment scale.
Within this research, different items are being investigated:

• Is it possible to make accurate estimates of catchment averaged evapotranspiration rates using different observation techniques (Bowen-Ratio, Eddy-Covariance, Scintillometer), or are other means needed as well?
• Can these estimations of the catchment averaged evapotranspiration be used to optimise flood forecasting models?