impact: overview

The Mekong River has the highest levels of biodiversity per unit area anywhere on the planet, including iconic and critically endangered species such as Irrawaddy River Dolphins. The Mekong’s hydrological and morphodynamic processes help sustain this ecosystem and a wide range of associated environmental services that impact on the lives of the region’s inhabitants, many of whom are poor and highly vulnerable to environmental change. For example, the Tonlé Sap Lake, SE Asia’s largest freshwater lake and the Mekong’s main fish nursery, provides the main source of protein for more than 3 million people. The Tonlé Sap Lake is fed by a reverse flow that is generated when water levels on the Mekong exceed those on the Tonlé Sap River, the tributary channel that normally drains the lake. Morphological changes at the junction of the Tonlé Sap and Mekong Rivers could therefore have a profound impact on the dynamics of this reverse flow and hence the sustainability of the lake.

However, of the many environmental problems extant within the Mekong Basin, arguably the most pressing concerns the sustainability of its delta. Home to more than 17 million people, and SE Asia’s most important rice basket, changes in fluvial sediment delivery to the Mekong delta have fundamental implications for flood risk, food security and migration because:

  1. fluvial sediment delivery is required for delta building and thus controls flood risk as sea-levels rise,
  2. reductions in fluvial sediment supply accelerate coastal erosion, which in turn can displace large numbers of people, and;
  3. fine-grained sediment deposition delivers the nutrients that sustain agricultural productivity.

The most challenging policy issues involve evaluating, and responding to, the impacts of future changes in sediment regimes associated with climate change and the likely construction of numerous hydropower dams on the Mekong and its tributaries in Cambodia and Laos . The STELAR team are contributing to these debates by working closely

Landsat 5 mosaic of the Mekong River delta

Landsat mosaic of the Mekong River delta

rice production on the Mekong River delta

the Mekong River delta is SE Asia's main rice producing area

with end-users to implement our models for a tailored suite of climate change and hydropower development scenarios. On these pages we highlight some of the ways in which the findings from our work are being used to achieve societal impact.