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| Titel |
South Asia river-flow projections and their implications for water resources |
| VerfasserIn |
C. Mathison, A. J. Wiltshire, P. Falloon, A. J. Challinor |
| 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 ; 19, no. 12 ; Nr. 19, no. 12 (2015-12-07), S.4783-4810 |
| Datensatznummer |
250120864
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| Publikation (Nr.) |
 copernicus.org/hess-19-4783-2015.pdf |
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| Zusammenfassung |
| South Asia is a region with a large and rising population, a high dependence
on water intense industries, such as agriculture and a highly variable
climate. In recent years, fears over the changing Asian summer monsoon (ASM)
and rapidly retreating glaciers together with increasing demands for water
resources have caused concern over the reliability of water resources and the
potential impact on intensely irrigated crops in this region. Despite these
concerns, there is a lack of climate simulations with a high enough
resolution to capture the complex orography, and water resource analysis is
limited by a lack of observations of the water cycle for the region. In this
paper we present the first 25 km resolution regional climate projections of
river flow for the South Asia region. Two global climate models (GCMs), which
represent the ASM reasonably well are downscaled (1960–2100) using a
regional climate model (RCM). In the absence of robust observations,
ERA-Interim reanalysis is also downscaled providing a constrained estimate of
the water balance for the region for comparison against the GCMs
(1990–2006). The RCM river flow is routed using a river-routing model to
allow analysis of present-day and future river flows through comparison with
available river gauge observations. We examine how useful these simulations
are for understanding potential changes in water resources for the South Asia
region. In general the downscaled GCMs capture the seasonality of the river
flows but overestimate the maximum river flows compared to the observations
probably due to a positive rainfall bias and a lack of abstraction in the
model. The simulations suggest an increasing trend in annual mean river flows
for some of the river gauges in this analysis, in some cases almost doubling
by the end of the century. The future maximum river-flow rates still occur
during the ASM period, with a magnitude in some cases, greater than the
present-day natural variability. Increases in river flow could mean
additional water resources for irrigation, the largest usage of water in this
region, but has implications in terms of inundation risk. These projected
increases could be more than countered by changes in demand due to depleted
groundwater, increases in domestic use or expansion of water intense
industries. Including missing hydrological processes in the model would make
these projections more robust but could also change the sign of the
projections. |
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