Opportunities for Future Elevation Gain from Sedimentation in the Mekong Delta

The Mekong Delta is one of the largest in the world, home to more than 17 million people and supporting internationally important agricultural productivity. Deltaic land naturally subsides as recently deposited sediment compacts, and so requires constant sediment input to maintain elevation relative to sea level. These processes are complicated by human activities, which prevent sediment deposition indirectly through reducing fluvial sediment supply and directly through the construction of infrastructure such as flood defences on deltas, impeding floods which deliver sediment to the land. On top of that, anthropogenic activities increase the rate of subsidence through over-exploitation of groundwater and other land-use practices. This research presents the potential for fluvial sediment delivery to compensate for sea-level rise and subsidence in the Mekong Delta during the 21st century. We use detailed elevation data and subsidence scenarios in combination with regional sea-level rise and fluvial sediment flux projections to quantify the potential for maintaining elevation relative to sea level in the Mekong delta. We present localised sedimentation scenarios in specific areas as examples, although the potential for sediment-based adaptation is complicated by existing land use. A change in water and sediment management is required to effectively use natural resources and employ these adaptation methods.