Fate of Mekong sediments - present understanding and uncertainties in future predictions Seminar

Fast growing economies in mainland Southeast Asia are facing the urge to find the balance between energy hungry development and environmental wellbeing. Whilst a large part of the population in countries such as Cambodia and Laos are depending on the natural resources for their livelihoods and food security, at the same time the large hydropower construction schemes in the Mekong –to largely meet the energy demands of the growth – are threatening the productive aquatic and floodplain ecosystems due to the altered flood pulse and trapped sediment loads.

At the same the population growth in the region is increasing the food demand and putting more pressure on the agriculture; planned to partly be overcome by large irrigation schemes, which would further impact on the flow regimes. The region is moreover facing rapid deforestation. Finally, climate change is predicted to add still another uncertainty factor to the future flow regimes, which are reportedly already experiencing abnormally high inter-annual variations within the last decades when looked at over a time-scale of several centuries.

All of these land surface disturbances have specific impacts on the river’s hydrology and sediment dynamics. The annual flood pulse, driven by monsoon climate, is essential for high productivity of aquatic ecosystems while sediment transport is critically important for aquatic ecology, fisheries, agriculture, water supply and river navigation. Although the understanding of the sediment transport in the Mekong is gradually growing, there are still many uncertainties related to the understanding of the current and future sediment fluxes. These are related to, for example
i. sediment dynamics in the floodplains
ii. impact of climate variability on sediment fluxes
iii. future climate change impacts on sediments
iv. cumulative impact of land surface disturbances on sediments loads

In the seminar presentation I will introduce the current understanding of Mekong’s hydrology and sediment dynamics. Moreover, the uncertainties in the future predictions of suspended sediment fluxes will be discussed.