Stefan Uhlenbrook and Dörthe Tetzlaff
This study addresses the effects of spatial and temporally
variable rainfall input data
on discharge simulation in a mountainous catchment.
The process-oriented catchment
model TAC-D was applied successfully to the meso scale
Brugga basin (40 km²) and the
sub-basin St. Wilhelmer Talbach (15.4 km²) located
at Southern Black Forest Mountains,
southwest Germany. Then the calibrated model was run
with two different precipitation
input data sets for three storm events:
- Basin precipitation was calculated using up to seven
ground stations and a regionalization
method that combines the inverse distance weighting
method with an elevation
- Weather radar data from a C-band radar were adjusted
using ground stations and the
basin precipitation was calculated.
This resulted in quite different precipitation patterns,
in particular for the storm cells with
limited spatial extent. Both precipitation data sets
were transferred to 50 x 50 m² grid, which
served as spatial discretization of the TACD model.
For the radar data an algorithm developed
by Jens Lange was used. The significance of the spatial
and temporal variability of the
precipitation input for flood modelling in mountainous
environments is clearly demonstrated.
Incorrect basin precipitation data can lead to large
errors in flood modelling. Radar data can help
to capture this variability of the precipitation, particularly
for events with very unequal rainfall
distribution. But they need to be adjusted using several
ground stations. For this a suitable
methodology is proposed. Finally the use of radar data
for hydrological modelling in mountainous
basins is discussed.