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| Titel |
Lessons learned from integrated hydrological modeling of ephemeral catchments with different land uses |
| VerfasserIn |
Matteo Camporese, Joshua Dean, Edoardo Daly |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250132930
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| Publikation (Nr.) |
 EGU/EGU2016-13483.pdf |
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| Zusammenfassung |
| Land use, in particular tree cover, has a strong influence on evapotranspiration (ET) and thus
a large effect on the water budget of ephemeral catchments in arid and semi-arid climates.
Unfortunately, the dearth of medium to long-term experimental observations in such areas
limits the understanding of the interplay between catchment geology, land use, and
climate in driving catchment water balance. Here we use four years (2011-2014) of
rainfall, streamflow, and groundwater level measurements to estimate the water
balance components in two small, adjacent, ephemeral catchments in a semi-arid
region of south-eastern Australia; one catchment was predominantly covered with a
eucalypt plantation established in July 2008 and the other was dedicated to grazing
pasture.
The integrated hydrological model CATHY (CATchment HYdrology) was calibrated
against the data in the two catchments using streamflow and groundwater level
observations in 2011; the data in the following years (2012-2014) were used for the model
validation.
The model was able to adequately reproduce the periods of flow in both catchments in all
years, although streamflow and groundwater levels were better reproduced in the pasture than
in the plantation. This can partly be attributed to the root growth of the trees, which is difficult
to estimate; the declining water storage in the eucalypt catchment could only be obtained
when including a simple model of root growth dynamics. Other sources of uncertainty could
be due to an imperfect description of the surface topography and bedrock geology, which
prevent us from accurately reproducing the effects of the tree furrows and subsurface wetness
connectivity.
The water balances estimated from both data and model showed a significant increase in
ET in the eucalypt plantation catchment at the expense of groundwater storage: ET accounted
for 95-104% of rainfall in the pasture catchment and 104-119% in the eucalypt
catchment across the four years studied. However, the observed streamflow decline in
the plantation was significantly less than predicted by the model, with streamflow
discharge ranging from 1 to 4% of rainfall in both catchments for the entire study
period.
Overall, the observed data and model simulations suggest the response of ephemeral
catchments to land use change is driven by complex interactions between climate, geology
and vegetation; long-term, data-rich, highly parameterized hyper-resolution modeling studies
are required to further separate these factors. |
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