1 - Centre de recherche public Gabriel Lippmann

CRP - Gabriel Lippmann 2009 Annual Report
1HYIMPACTS
Title
Hydrometeorological model uncertainty and
rainfall/model sensitivity analysis in the Sauer
River (Germany/Luxembourg) catchment
Fields
radar remote sensing, hydrology,
hydrological and atmospheric modelling
Partner
Université Technique de Delft (NL)
Project leader
Klaus Görgen
Period
June 2008 - May 2011
Environment and Agro-biotechnologies
(EVA) department
Subject
The limit conditions (i.e. precipitation and evapotranspiration), the equations describing the propagation of water within the “catchment area” system, and the model’s
parameters represent the main sources of uncertainties that could affect hydrological forecasts. This project’s objective is to assess the contribution of meteorological
radar and of atmospheric models in the reduction of uncertainties related to hydrological simulations. Initially, this will involve comparing various indirect rain field estimation
methods with the measurements recorded in situ, at rainfall stations. A study will then be carried out in order to assess the contribution of each data set for the
hydrological modelling. For the purposes of a better characterization of the spatial distribution of flood genesis processes, a hydrological model will be progressively
developed in order to allow optimum integration of the estimated rain fields on a regional scale, respectively by meteorological radar and by atmospheric model.
This project is co-financed by the [Luxembourg] National Research Fund (FNR) as part of the Aides à la formation-recherche (AFR - Training-research aid).
Results
The selective approach targets the integration, in a non-distributed hydrological model, of the information on the spatial distribution of the rain coming from a database
of images from a meteorological radar. The method is based on a calculation of the distances between a catchment area’s rain fields, estimated by radar, and the
basin’s outlet. The distances are related to the average distance from the overall basin. This approach is used to calculate, for each time step, the ratio that describes
the rain field’s instantaneous position within the catchment area. The ratios have values between 0 (rain falling near the outlet) and 2 (rain falling at the basin’s extreme
limits relative to the outlet). Finally, these data are used to integrate information on the spatial distribution of the rain into a hydrological model, while manipulating the
transfer time estimated by the model. The model was applied to the Alzette catchment basin in 2006-2007 and most particularly during two rain events spaced three
days apart. The preliminary results show that the proposed approach serves to better simulate the arrival of successive flood waves coming from different parts of
the catchment area.