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| Titel |
The use of topographic indices as predictors of the energy fluxes in the Rur catchment |
| VerfasserIn |
Alessandra Trevisan, Victor Venema, Stefan Kollet, Clemens Simmer |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250110122
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| Publikation (Nr.) |
 EGU/EGU2015-10095.pdf |
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| Zusammenfassung |
| Subsurface hydrodynamics is a fundamental component of the hydrologic cycle and a key
factor in the determination of the land surface processes. Therefore, we simulate the
ground-vegetation-atmosphere system with a fully coupled subsurface-land surface model
over the Rur catchment, Germany.
The 3D parallel watershed model ParFlow computes the water flow at the surface and in
the subsurface, while the physical and biogeochemical processes at the land surface are
simulated by the Community Land Model CLM. The weather prediction and climate model
of the German weather service, COSMO, provides the atmospheric forcing for the
simulation. The exchange of variables and energy fluxes between the models ensures the
physical consistency of the system.
This study is part of the MiKlip program on seamless decadal climate prediction.
For this purpose decadal runs are needed, which are not feasible with the above
mentioned model environment at high resolution. In order to reduce the computational
burden of a fully coupled simulation, a Model Complexity Reduction Approach is
proposed, which intelligently combines full complex system runs and simplified
simulations. To correct the simplified runs towards the full runs, statistical rules are
applied. We assess the influence of selected predictors on the energy fluxes at the
surface.
The computational domain (on the order of 106 km2) presents heterogeneous land use,
soil texture and topography, which were the first intuitive classifiers of the different
grid cells. The analysis of individual and correlated effects on the energy fluxes,
suggested to focus on the topography and particularly on compound indices, such
as modified topographic wetness index (TI) and depth-to-water index (DTW) as
proxies for the availability of soil moisture for transpiration and evaporation. TI and
DTW were determined based on the slope of the cell, the specific contributing area
and distance to surface water, thus both carry information on the specific grid cell
and the grid cells that are hydrologically related to it. The first-order effects of
vegetation (e.g. root depth) and soil composition (e.g. porosity, hydraulic conductivity)
are also taken into account for their relation to the topography of the catchment. |
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