The Mekong delta in Vietnam is experiencing high rates of land subsidence due to excessive groundwater extraction, driven by rapid urbanization, land-use change, and intensification of agricultural and economic activities. If anthropogenically-induced subsidence is not mitigated soon, it will seriously increase flood risk and may drive out-migration of millions of delta inhabitants.
In 2014, as part of the Urbanizing Deltas of the World programme, researchers at the Water, Climate and Future Deltas hub launched the Rise and Fall project to investigate land subsidence in the Mekong delta. One of their major findings was that the average elevation of the delta is only 80 cm above mean sea level which is much lower than the formerly estimated 2.6 m. This contributed to making land subsidence a growing concern and increased the urgency of implementing measures to mitigate subsidence. However, most investments in the region still focus on economic development and livelihood. There is no long-term mitigation and adaptation strategy that addresses land subsidence. Rather, residents adapt once they have been flooded.
Current policy approach
On the national level, the Vietnamese government has developed standards to limit groundwater extraction in the Mekong delta. However, law enforcement falls short because professional and financial capacities are lacking to control a large number of wells which leads to higher extraction volumes than permitted. Moreover, the centralised structure of the Vietnamese governance hinders the implementation of tailor-made measures by limiting the role of farmers in decision-making, as key users and in possession of practical knowledge of groundwater extraction and water need. Instead, solutions initiated at the community level are not formally recognized and actively disseminated by authorities.
Recommendations from the Rise and Fall project
Developing strategies to reduce the rate of groundwater extraction has to be top priority
“Developing strategies to reduce the rate of groundwater extraction has to be top priority”, says Philip Minderhoud, researcher in land subsidence, geomorphology and hydrogeology in deltas. The national government therefore needs to work on policy formulation on regulating groundwater extraction and on steering future economic and spatial development i.e. required land-use change. It should also focus on improving surface water quality and promoting other alternative freshwater sources, such as rainwater harvesting.
Stakeholder involvement and long-term programme
During this process, the involvement of local stakeholders, in particular local governments and resource users (especially farmers), is crucial. Carel Dieperink, senior researcher in multilevel water governance: “Alternatives to groundwater use must be actively promoted through governmental campaigns to ensure public support”. Furthermore, funding and a long-term programme to tackle land subsidence in the Mekong delta are required to develop and implement adaptation measures, such as the development of evacuation plans and the cultivation of salt-resistant crops.