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| Titel |
Applying simple water-energy balance frameworks to predict the climate sensitivity of streamflow over the continental United States |
| VerfasserIn |
M. Renner, C. Bernhofer |
| 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 ; 16, no. 8 ; Nr. 16, no. 8 (2012-08-07), S.2531-2546 |
| Datensatznummer |
250013411
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| Publikation (Nr.) |
 copernicus.org/hess-16-2531-2012.pdf |
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| Zusammenfassung |
The prediction of climate effects on terrestrial ecosystems and water
resources is one of the major research questions in hydrology. Conceptual
water-energy balance models can be used to gain a first order estimate of how
long-term average streamflow is changing with a change in water and energy
supply. A common framework for investigation of this question is based on the
Budyko hypothesis, which links hydrological response to aridity. Recently,
Renner et al. (2012) introduced the climate change impact hypothesis
(CCUW), which is based on the assumption that the total efficiency of the
catchment ecosystem to use the available water and energy for actual
evapotranspiration remains constant even under climate changes.
Here, we confront the climate sensitivity approaches (the Budyko approach of Roderick
and Farquhar, 2011, and the CCUW) with data of more than 400 basins
distributed over the continental United States. We first estimate the
sensitivity of streamflow to changes in precipitation using long-term average
data of the period 1949 to 2003. This provides a hydro-climatic status of the
respective basins as well as their expected proportional effect to changes in
climate. Next, we test the ability of both approaches to predict climate
impacts on streamflow by splitting the data into two periods. We (i) analyse
the long-term average changes in hydro-climatology and (ii) derive a
statistical classification of potential climate and basin change impacts
based on the significance of observed changes in runoff, precipitation and
potential evapotranspiration. Then we (iii) use the different climate
sensitivity methods to predict the change in streamflow given the observed
changes in water and energy supply and (iv) evaluate the predictions by (v)
using the statistical classification scheme and (vi) a conceptual approach to
separate the impacts of changes in climate from basin characteristics change
on streamflow. This allows us to evaluate the observed changes in streamflow
as well as to assess the impact of basin changes on the validity of climate
sensitivity approaches.
The apparent increase of streamflow of the majority of basins in the US is
dominated by an increase in precipitation. It is further evident that impacts
of changes in basin characteristics appear simultaneously with climate
changes. There are coherent spatial patterns with catchments where basin
changes compensate for climatic changes being dominant in the western and
central parts of the US. A hot spot of basin changes leading to excessive
runoff is found within the US Midwest.
The impact of basin changes on the prediction is large and can be twice as much as the observed change signal.
Although the CCUW and the Budyko approach yield similar predictions for most
basins, the data of water-limited basins support the Budyko framework rather
than the CCUW approach, which is known to be invalid under limiting climatic
conditions. |
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