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| Titel |
Water balance simulations for major German river basins |
| VerfasserIn |
Matthias Zink, Rohini Kumar, Luis Samaniego |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250052997
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| Zusammenfassung |
| Accurate and reliable predictions of water fluxes and state variables such as soil moisture or
evapotranspiration in large river basins are required for flood forecasting, drought mitigation,
climate change impact assessment, water resource management, among others. The objective
of this study is to simulate the water balance of the five largest rivers within Germany:
Danube, Elbe, Rhine, Weser, and Ems. To achieve this goal, the recently developed, process
based spatial distributed hydrological model mHM (Samaniego et. al., 2010, WRR) was set
up in these basins. mHM uses a multiscale parameter regionalization (MPR) scheme,
which relates model parameters to catchment characteristics through a set of transfer
functions and few global parameters. The latter could be estimated via calibration at
locations where discharge information is available. At ungauged locations, MPR
offers a possibility to use the global parameters obtained at other similar locations
to run the model. mHM was driven by grided fields of daily meteorological data
(e.g. precipitation, temperature), which were interpolated from point measurements
using external drift Kriging. Data of 5600 rain gauges and 1100 meteorological
stations obtained from German Weather Service (DWD) over Germany during the
period from 1950 to 2010 were used for this interpolation. Additional information
at a spatial resolution of 100Ã100Â m required to set up mHM comprise a digital
elevation model DEM (BKG) and its related characteristics (e.g. slope, aspect, flow
direction, flow accumulation), soil properties (BUEK, 1Â :Â 1Â 000Â 000), CORINE
land cover maps, and hydrological conductivity of geological formations (HUEK,
1Â :Â 1Â 000Â 000). Daily stream flow of more than 100 runoff gauging stations were
provided by GRDC and EWA. Model simulations were carried out on a spatial
resolution of 4Ã4Â km at hourly time steps. The model was calibrated in the period
from 1990 to 2000 and evaluated in two periods: 1960-1989 and 2001-2008. Two
years of data prior to both periods were set to spin-up the model. Evaluation runs
showed a good approximation of the observed daily streamflow. Nash-Sutcliffe
efficiencies (NSE) for these river basins varied between 0.7 and 0.9. Monthly and
yearly long term water balance were satisfactorily closed. Simulated and observed
values exhibited a correlation coefficient larger than 0.9 in all cases. Results of proxy
basin tests (i.e. crossvalidation) indicated that mHM is able to reproduce the daily
streamflow statistics reasonably well. The least NSE obtained in these tests was 0.5.
Currently we are investigating the ability of the model to reproduce extreme runoff
characteristics (e.g. magnitude frequency of floods and droughts) and other state
variables. |
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