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| Titel |
A weather dependent approach to estimate the annual course of vegetation parameters for water balance simulations on the meso- and macroscale |
| VerfasserIn |
K. Förster, M. Gelleszun, G. Meon |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7340
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| Digitales Dokument |
URL |
| Erschienen |
In: Proceedings of the 15th Workshop on Large-scale Hydrological Modelling ; Nr. 32 (2012-12-11), S.15-21 |
| Datensatznummer |
250017320
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| Publikation (Nr.) |
 copernicus.org/adgeo-32-15-2012.pdf |
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| Zusammenfassung |
| In order to simulate long-term water balances hydrologic models have to be
parameterized for several types of vegetation. Furthermore, a seasonal
dependence of vegetation parameters has to be accomplished for a successful
application. Many approaches neglect inter-annual variability and shifts due
to climate change. In this paper a more comprehensive approach from
literature was evaluated and applied to long-term water balance simulations,
which incorporates temperature, humidity and maximum bright sunshine hours
per day to calculate a growing season index (GSI). A validation of this
threshold-related approach is carried out by comparisons with normalized
difference vegetation index (NDVI) data and observations from the
phenological network in the state of Lower Saxony. The annual courses of GSI
and NDVI show a good agreement for numerous sites. A comparison with
long-term observations of leaf onset and offset taken from the phenological
network also revealed a good model performance. The observed trends
indicating a shift toward an earlier leaf onset of 3 days per decade in the
lowlands were reproduced very well. The GSI approach was implemented in the
hydrologic model Panta Rhei. For the common vegetation parameters like leaf
area index, vegetated fraction, albedo and the vegetation height a minimum
value and a maximum value were defined for each land surface class. These
parameters were scaled with the computed GSI for every time step to obtain a
seasonal course for each parameter. Two simulations were carried out each for
the current climate and for future climate scenarios. The first run was
parameterized with a static annual course of vegetation parameters. The
second run incorporates the new GSI approach. For the current climate both
models produced comparable results regarding the water balance. Although
there are no significant changes in modeled mean annual evapotranspiration
and runoff depth in climate change scenarios, mean monthly values of these
water balance components are shifted toward a lower runoff in spring and
higher values during the winter months. |
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