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| Titel |
Large-scale runoff generation – parsimonious parameterisation using high-resolution topography |
| VerfasserIn |
L. Gong, S. Halldin, C.-Y. Xu |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 15, no. 8 ; Nr. 15, no. 8 (2011-08-11), S.2481-2494 |
| Datensatznummer |
250012921
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| Publikation (Nr.) |
 copernicus.org/hess-15-2481-2011.pdf |
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| Zusammenfassung |
| World water resources have primarily been analysed by global-scale
hydrological models in the last decades. Runoff generation in many of these
models are based on process formulations developed at catchments scales. The
division between slow runoff (baseflow) and fast runoff is primarily
governed by slope and spatial distribution of effective water storage
capacity, both acting at very small scales. Many hydrological models, e.g.
VIC, account for the spatial storage variability in terms of statistical
distributions; such models are generally proven to perform well. The
statistical approaches, however, use the same runoff-generation parameters
everywhere in a basin. The TOPMODEL concept, on the other hand, links the
effective maximum storage capacity with real-world topography. Recent
availability of global high-quality, high-resolution topographic data makes
TOPMODEL attractive as a basis for a physically-based runoff-generation
algorithm at large scales, even if its assumptions are not valid in flat
terrain or for deep groundwater systems. We present a new runoff-generation
algorithm for large-scale hydrology based on TOPMODEL concepts intended to
overcome these problems. The TRG (topography-derived runoff generation)
algorithm relaxes the TOPMODEL equilibrium assumption so baseflow generation
is not tied to topography. TRG only uses the topographic index to distribute
average storage to each topographic index class. The maximum storage
capacity is proportional to the range of topographic index and is scaled by
one parameter. The distribution of storage capacity within large-scale grid
cells is obtained numerically through topographic analysis. The new
topography-derived distribution function is then inserted into a
runoff-generation framework similar VIC's. Different basin parts are
parameterised by different storage capacities, and different shapes of the
storage-distribution curves depend on their topographic characteristics. The
TRG algorithm is driven by the HydroSHEDS dataset with a resolution of 3"
(around 90 m at the equator). The TRG algorithm was validated against the
VIC algorithm in a common model framework in 3 river basins in different
climates. The TRG algorithm performed equally well or marginally better than
the VIC algorithm with one less parameter to be calibrated. The TRG
algorithm also lacked equifinality problems and offered a realistic spatial
pattern for runoff generation and evaporation. |
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