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| Titel |
A multimodel ensemble approach to assessment of climate change impacts on the hydrology and water resources of the Colorado River Basin |
| VerfasserIn |
N. S. Christensen, D. P. Lettenmaier |
| 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 ; 11, no. 4 ; Nr. 11, no. 4 (2007-07-09), S.1417-1434 |
| Datensatznummer |
250009396
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| Publikation (Nr.) |
 copernicus.org/hess-11-1417-2007.pdf |
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| Zusammenfassung |
| Implications of 21st century climate change on the hydrology and water
resources of the Colorado River Basin were assessed using a multimodel
ensemble approach in which downscaled and bias corrected output from 11
General Circulation Models (GCMs) was used to drive macroscale hydrology and
water resources models. Downscaled climate scenarios (ensembles) were used
as forcings to the Variable Infiltration Capacity (VIC) macroscale hydrology
model, which in turn forced the Colorado River Reservoir Model (CRMM).
Ensembles of downscaled precipitation and temperature, and derived
streamflows and reservoir system performance were assessed through
comparison with current climate simulations for the 1950–1999 historical
period. For each of the 11 GCMs, two emissions scenarios (IPCC SRES A2 and
B1, corresponding to relatively unconstrained growth in emissions, and
elimination of global emissions increases by 2100) were represented. Results
for the A2 and B1 climate scenarios were divided into three periods:
2010–2039, 2040–2069, and 2070–2099. The mean temperature change averaged
over the 11 ensembles for the Colorado basin for the A2 emission scenario
ranged from 1.2 to 4.4°C for periods 1–3, and for the B1 scenario from
1.3 to 2.7°C. Precipitation changes were modest, with ensemble mean
changes ranging from −1 to −2% for the A2 scenario, and from +1 to −1%
for the B1 scenario. An analysis of seasonal precipitation patterns
showed that most GCMs had modest reductions in summer precipitation and
increases in winter precipitation. Derived April 1 snow water equivalent
declined for all ensemble members and time periods, with maximum (ensemble
mean) reductions of 38% for the A2 scenario in period 3. Runoff
changes were mostly the result of a dominance of increased
evapotranspiration over the seasonal precipitation shifts, with ensemble
mean runoff changes of −1, −6, and −11% for the A2 ensembles, and 0,
−7, and −8% for the B1 ensembles. These hydrological changes were
reflected in reservoir system performance. Average total basin reservoir
storage and average hydropower production generally declined, however there
was a large range across the ensembles. Releases from Glen Canyon Dam to the
Lower Basin were reduced for all periods and both emissions scenarios in the
ensemble mean. The fraction of years in which shortages occurred increased
by approximately 20% by period 3 for both emissions scenarios. |
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