Abstract
A MIKE SHE model of the Mekong, calibrated and validated for 12 gauging stations, is used to simulate climate change scenarios associated with a 2°C increase in global mean temperature projected by seven general circulation models (GCMs). Impacts of each scenario on the river ecosystem and, hence, uncertainty associated with different GCMs are assessed through an environmental flow method based on the range of variability approach. Ecologically relevant hydrological indicators are evaluated for the baseline and each scenario. Baseline-to-scenario change is assessed against thresholds that define likely risk of ecological impact. They are aggregated into single scores for high and low flows. The results demonstrate considerable inter-GCM differences in risk of change. Uncertainty is larger for low flows, with some GCMs projecting high and medium risk at the majority of locations, and others suggesting widespread no or low risk. Inter-GCM differences occur along the main Mekong, as well as within major tributaries.Editor Z.W. KundzewiczCitation Thompson, J.R., Laizé, C.L.R., Green, A.J., Acreman, M.C., and Kingston, D.G., 2014. Climate change uncertainty in environmental flows for the Mekong River. Hydrological Sciences Journal, 59 (3–4), 935–954.
Highlights
Southeast Asia’s Mekong River is one of the most iconic rivers in the world
Earlier assessments of the hydrological impacts and associated uncertainty of projections from the different general circulation models (GCMs) have been extended using the ecological risk due to flow alteration (ERFA) screening method. This permits the risk of alteration of the river ecosystem resulting from hydrological change to be determined and provides a means of assessing GCM-related uncertainty for projections of future environmental flows
The results demonstrate the critical importance of GCM-related uncertainty for assessing climate change impacts on environmental flows, with direct links clearly apparent from uncertainty in GCM projections to simulated discharge and, in turn, environmental flows
Summary
The Mekong’s waters bring direct benefits to people, including water for public supply, power generation, food—such as rice—as well as fish and aquatic plants. Its flow of river water has significant social and spiritual meaning to local communities and supports important species, such as the emblematic sub-population of the Irrawaddy dolphin (Orcaella brevirostris) and the Mekong giant catfish (Pangasianodon gigas; Hogan et al 2004). All of these attributes are commonly referred to as ecosystem services (Fischer et al 2009, Maltby and Acreman 2011). The world’s rivers are changing due to multiple pressures including land-use change, water diversions, dams and climate change, which will have implications for their ecosystem services (Millennium Ecosystem Assessment 2005, Vörösmarty et al 2010)
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