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Uncertainty in climate change projections of discharge for the Mekong River Basin

Kingston, DG; Thompson, JR; Kite, G; (2011) Uncertainty in climate change projections of discharge for the Mekong River Basin. Hydrology and Earth System Sciences , 15 (5) pp. 1459-1471. 10.5194/hess-15-1459-2011. Green open access

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Abstract

The Mekong River Basin is a key regional resource in Southeast Asia for sectors that include agriculture, fisheries and electricity production. Here we explore the potential impacts of climate change on freshwater resources within the river basin. We quantify uncertainty in these projections associated with GCM structure and climate sensitivity, as well as from hydrological model parameter specification. This is achieved by running pattern-scaled GCM scenarios through a semi-distributed hydrological model (SLURP) of the basin. Pattern-scaling allows investigation of specific thresholds of global climate change including the postulated 2 degrees C threshold of "dangerous" climate change. Impacts of a 2 degrees C rise in global mean temperature are investigated using seven different GCMs, providing an implicit analysis of uncertainty associated with GCM structure. Analysis of progressive changes in global mean temperature from 0.5 to 6 degrees C above the 1961-1990 baseline (using the HadCM3 GCM) reveals a relatively small but non-linear response of annual river discharge to increasing global mean temperature, ranging from a 5.4% decrease to 4.5% increase. Changes in mean monthly river discharge are greater (from -16% to +55%, with greatest decreases in July and August, greatest increases in May and June) and result from complex and contrasting intra-basin changes in precipitation, evaporation and snow storage/melt. Whilst overall results are highly GCM dependent (in both direction and magnitude), this uncertainty is primarily driven by differences in GCM projections of future precipitation. In contrast, there is strong consistency between GCMs in terms of both increased potential evapotranspiration and a shift to an earlier and less substantial snowmelt season. Indeed, in the upper Mekong (Lancang sub-basin), the temperature-related signal in discharge is strong enough to overwhelm the precipitation-related uncertainty in the direction of change in discharge, with scenarios from all GCMs leading to increased river flow from April-June and decreased flow from July-August.

Type: Article
Title: Uncertainty in climate change projections of discharge for the Mekong River Basin
Open access status: An open access version is available from UCL Discovery
DOI: 10.5194/hess-15-1459-2011
Language: English
Additional information: © D. G. Kingston, J. R. Thompson, and G. Kite. This work is distributed under the Creative Commons Attribution 3.0 License (CC BY) 3.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Keywords: WATER-RESOURCES, HYDROLOGICAL MODEL, CHANGE IMPACTS, GROUNDWATER, ENSEMBLE, COVER, VARIABILITY, STREAMFLOW, CATCHMENT, SCENARIOS
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL SLASH
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS > Dept of Geography
URI: https://discovery.ucl.ac.uk/id/eprint/1312528
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