SUSPENDED SEDIMENT DYNAMICS CHANGES IN MEKONG RIVER BASIN: POSSIBLE IMPACTS OF DAMS AND CLIMATE CHANGE

Abstract

This paper evaluates the potential impact of climate change and dams on suspended sediment
(SS) dynamics in the Mekong River Basin (MRB). To this end, a distributed process-based sediment transport
model was used to examine the potential impact of future climate and dams on suspended sediment dynamics
changes in the MRB. Climate scenarios from two GCMs outputs together with effects of 3 existing, 5 under
construction and 11 planned dams were considered in the scenario analysis. The simulation results show that
the reductions in annual suspended sediment load (SSL) are likely to range from a 20 to 33%, 41 to 62%, and
71 to 81% for existing, under construction, and planned dams respectively in case of no climate change for
baseline scenario (1991-2000). Moreover, the reductions on sediment concentration (SSC) are even greater
(23% to 78%) due to the potential impact of dams. In contrast, the SSL and SSC shows 40% to 92% increase
in the near future (2041-2050) and 28% to 90% in the far future (2090-2099). As the projected climate change
impact of sediment varies remarkably between the different climate models, the uncertainty should be taken
into account in sediment management. Overall, the changes in SSL and SSC can have a great implication for
planned reservoirs and related sediment management.