The Mekong River Basin: Landscape-scale Changes to Biophysical Processes
Abstract
In the Mekong River Basin, a dynamic interplay of tectonics and hydrology has created a biophysical system in which sediment and nutrients borne by the annual floodpulse support an extraordinarily high aquatic productivity. While millions of people depend on the river for their livelihood, the six riparian countries of the Mekong are experiencing rapid economic growth and aim to exploit river resources for direct economic benefits. Construction of hydropower dams, aggregate mines, flood-control dykes, and groundwater-irrigated agriculture have all provided short-term economic benefits, but threaten the natural functioning of the river and its floodplains. The survival of the Mekong Delta as a landform is threatened by reduction in sediment supply, dykes that prevent sediment deposition over the Delta surface, accelerated subsidence from groundwater pumping, and rising sea level. Ongoing and recently published research indicate that continued business as usual will put nearly half of the Delta's land surface below sea level by 2100, with the remaining areas impacted by salinization and frequent flooding. Planning to date has not recognized the existential nature of the threat to the Delta or the need to approach drivers of subsidence on a basin-scale rather than via local measures. Similarly, the extremely productive riverine fishery (including Tonle Sap) is threatened by dams via at least three mechanisms: preventing reproduction of important fish species by blocking fish migration, alterations to hydrology, and reduced sediment and nutrient loads due to trapping by dams. Many livelihoods in the basin depend on ecosystem services that will be strongly impacted by alterations of flow, nutrient, and sediment transport processes that drive river and delta morpho-dynamics. These threats can be understood and addressed only in the context of processes in the entire river basin. Making the unique human-biophysical system of the Mekong resilient to change and to find equitable trade-offs between biodiversity, ecosystem services, and economic development will require envisioning management plans that accommodate connected flow and sediment transport processes on the scale of the whole basin.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMEP34A..01K
- Keywords:
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- 0442 Estuarine and nearshore processes;
- BIOGEOSCIENCES;
- 0481 Restoration;
- BIOGEOSCIENCES;
- 1813 Eco-hydrology;
- HYDROLOGY;
- 1825 Geomorphology: fluvial;
- HYDROLOGY