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| Titel |
A comparative analysis of projected impacts of climate change on river runoff from global and catchment-scale hydrological models |
| VerfasserIn |
S. N. Gosling, R. G. Taylor, N. W. Arnell, M. C. Todd |
| 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. 1 ; Nr. 15, no. 1 (2011-01-21), S.279-294 |
| Datensatznummer |
250012602
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| Publikation (Nr.) |
 copernicus.org/hess-15-279-2011.pdf |
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| Zusammenfassung |
We present a comparative analysis of projected impacts of climate change on
river runoff from two types of distributed hydrological model, a global
hydrological model (GHM) and catchment-scale hydrological models (CHM).
Analyses are conducted for six catchments that are global in coverage and
feature strong contrasts in spatial scale as well as climatic and
developmental conditions. These include the Liard (Canada), Mekong (SE
Asia), Okavango (SW Africa), Rio Grande (Brazil), Xiangxi (China) and
Harper's Brook (UK). A single GHM (Mac-PDM.09) is applied to all catchments
whilst different CHMs are applied for each catchment. The CHMs include SLURP
v. 12.2 (Liard), SLURP v. 12.7 (Mekong), Pitman (Okavango), MGB-IPH (Rio
Grande), AV-SWAT-X 2005 (Xiangxi) and Cat-PDM (Harper's Brook). The CHMs
typically simulate water resource impacts based on a more explicit
representation of catchment water resources than that available from the GHM
and the CHMs include river routing, whereas the GHM does not. Simulations of
mean annual runoff, mean monthly runoff and high (Q5) and low (Q95) monthly
runoff under baseline (1961–1990) and climate change scenarios are
presented. We compare the simulated runoff response of each hydrological
model to (1) prescribed increases in global-mean air temperature of 1.0,
2.0, 3.0, 4.0, 5.0 and 6.0 °C relative to baseline from the UKMO HadCM3
Global Climate Model (GCM) to explore response to different amounts of
climate forcing, and (2) a prescribed increase in global-mean air
temperature of 2.0 °C relative to baseline for seven GCMs to explore
response to climate model structural uncertainty.
We find that the differences in projected changes of mean annual runoff
between the two types of hydrological model can be substantial for a given
GCM (e.g. an absolute GHM-CHM difference in mean annual runoff
percentage change for UKMO HadCM3 2 °C warming of up to 25%), and
they are generally larger for indicators of high and low monthly runoff.
However, they are relatively small in comparison to the range of projections
across the seven GCMs. Hence, for the six catchments and seven GCMs we
considered, climate model structural uncertainty is greater than the
uncertainty associated with the type of hydrological model applied. Moreover,
shifts in the seasonal cycle of runoff with climate change are represented
similarly by both hydrological models, although for some catchments the
monthly timing of high and low flows differs. This implies that for studies
that seek to quantify and assess the role of climate model uncertainty on
catchment-scale runoff, it may be equally as feasible to apply a GHM
(Mac-PDM.09 here) as it is to apply a CHM, especially when climate modelling
uncertainty across the range of available GCMs is as large as it currently
is. Whilst the GHM is able to represent the broad climate change signal that
is represented by the CHMs, we find however, that for some catchments there
are differences between GHMs and CHMs in mean annual runoff due to
differences in potential evapotranspiration estimation methods, in the
representation of the seasonality of runoff, and in the magnitude of changes
in extreme (Q5, Q95) monthly runoff, all of which have implications for
future water management issues. |
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