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| Titel |
Process-based modeling of vegetation dynamics, snow, evapotranspiration and soil moisture patterns in an alpine catchment |
| VerfasserIn |
Giacomo Bertoldi, Stefano Della Chiesa, Michael Engel, Georg Niedrist, Johannes G. Brenner, Stefano Endrizzi, Matteo Dall'Amico, Emanuele Cordano, Ulrike Tappeiner, Riccardo Rigon |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250096345
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| Publikation (Nr.) |
 EGU/EGU2014-11842.pdf |
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| Zusammenfassung |
| Mountain regions are particularly sensitive to climate change and at the same time
they represent a key water resource not only locally but as well for lowland areas.
Because of the complexity of mountain landscapes and the high climatic variability
at a local scale, detailed quantification of key water budget components as snow
cover, soil moisture and groundwater recharge is required. Therefore, there is a
strong need to improve the capability of hydrological models to identify patterns
in complex terrain (i.e. when variability of spatial characteristics counts), and to
quantify changes of the water cycle components explicitly, considering interactions
and feedbacks with climate and vegetation. Process-based hydrological models
represent promising tools for addressing those needs. However, even if their inherent
complexity sometimes limits their applicability for operational purpose, they offer
great potential in terms of tools to test hypotheses, which can be verified in the
field.
GEOtop is a hydrological model that calculates the energy and mass exchanges between
soil, vegetation, and atmosphere, accounting for land cover, water redistribution, snow
processes, glacier mass budget and the effects of complex terrain and thus is one of the
few models that was built with this complexity in mind. Recently, it has also been
coupled with a dynamic vegetation model in order to simulate alpine grassland
ecosystems.
In this contribution, we want to present an application of the GEOtop model in simulating
above ground biomass (Bag) production, evapotranspiration (ET), soil moisture (SM) and
snow water equivalent (SWE) patterns for a catchment of about 100 km2, located in the
Venosta/Vinschgau valley in the European Alps. Despite the Alps are one of the “water
towers of Europe”, water scarcity issues can affect the region where the model
is applied, and an intensive hydrological and ecological monitoring activity with
ground observations and remote-sensing products has been established in the last five
years.
Simulations results showed that, along south-facing slopes, ET and Bag did not decrease
with elevation, as it happens along north facing slopes, but showed a maximum at an
intermediate elevation around ca. 1500 m a.s.l., because of the contrasting trends of a
shorter vegetation season at higher elevations and water stress at lower elevations.
Therefore, results suggest that in this region south-facing pastures and woodlands
below the elevation band of 1000 – 1500 m a.s.l. are the locations exposed to more
frequent water stress conditions. Future climate change will likely worsen drought
frequency.
This contribution highlights that the collected data set permits a multi-scale and
multi-process evaluation of the model. Plot scale observations of evapotranspiration, soil
moisture and snow cover, combined with remote sensing observations of snow and soil
moisture help to discriminate between uncertainties in input data (i.e. snow/rainfall
partitioning) and model parameterization. Moreover, we want to show with practical
examples how, when dealing with coupled process-based eco-hydrological models is
essential considering the physical consistency between different processes as modeled in
GEOtop. For example, accounting the role of subsurface water lateral distribution
on surface soil moisture; considering both water and energy budget constrains;
introducing the control of snow cover on vegetation phenology. This introduces additional
constraints in model parameterization that allow a better understanding of some
processes dynamics, and can lead to a more coherent and accurate estimation of the
catchment hydrological behavior than the one, which is possible with simpler models. |
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