The Mekong Delta is facing a convergence of environmental pressures that are reshaping one of the world’s most important agricultural and ecological regions. Sea-level rise, saltwater intrusion, drought and flooding are unfolding alongside hydropower development, sand mining, groundwater extraction and intensive agriculture—making it increasingly difficult to separate the effects of climate change from those of human intervention.
In this interview, Edward Park, Head of the Humanities and Social Studies Education Department and Associate Professor of Physical Geography at Nanyang Technological University’s National Institute of Education, examines how the Mekong Delta has changed and how communities and policymakers are responding. As a Principal Investigator at the Earth Observatory of Singapore, Park draws on satellite remote sensing, hydrological modelling and field research to study sediment dynamics, sand mining, groundwater and human–river interactions. He discusses the evolution from engineering-heavy approaches such as dykes and flood-control infrastructure toward more flexible adaptation strategies, including crop diversification, rice–shrimp farming and the protection of natural ecosystems. He also explains why sediment loss and sand mining deserve to be considered part of the climate-adaptation debate, and what lessons the Mekong may offer other river deltas confronting a rapidly changing climate.
You are an Associate Professor of Physical Geography at Nanyang Technological University in Singapore, where your research focuses on the environmental and hydrological changes affecting the Mekong River and its delta. Could you give a timeline of these changes (sea-level rise, saltwater intrusion, floods, and droughts…)?
The environmental and hydrological changes in the Mekong Delta are best understood not as a single sequence of climate-related events, but as the cumulative result of interacting climatic and human pressures. Since the 1990s, increasing upstream dam development, with mega dams mostly on the main stream located in China, has altered natural flow regimes (both floods and droughts) and substantially reduced sediment delivery to the delta. Over the 2000s and 2010s, intensive riverbed sand mining and groundwater extraction added further pressure, contributing to channel incision, sediment starvation and land subsidence exacerbated untill now. At the same time, sea-level rise has increased the delta's relative exposure to urban flooding which could be increasingly observed in recent years. These processes have made droughts and saltwater intrusion particularly damaging. For example, reduced dry-season river flows can allow salinity to penetrate farther inland, while subsidence lowers the land surface relative to the sea. Importantly, recent modelling shows that sand mining itself is a substantial contributor to salinity intrusion, rather than merely a secondary environmental problem.
And what about a timeline of the adaptation measures? Could you describe what practical measures have been implemented?
Historically, adaptation in the Mekong Delta relied strongly on engineering approaches, including dykes (both large-scale ring dykes and agricultural polders), embankments, canals and water-control infrastructure which mostly increased after 1986 for national food security in Vietnam. These measures supported flood protection and intensive rice production, including double- and triple-cropping systems. However, as the limitations and unintended consequences of trying to control the delta have become clearer, particularly in the context of subsidence and changing salinity regimes, there has been a gradual shift toward a more flexible “living with the delta” approach. More recent adaptation therefore includes crop diversification, rice–shrimp systems, salt-tolerant crops, mangrove and wetland restoration, improved water management, and efforts to reduce groundwater extraction and excessive sand mining. The important change is not simply replacing hard infrastructure with nature-based solutions, but moving toward a combination of measures that works with the delta's natural processes while protecting people and critical infrastructure.
Could you explain why the Mekong River and its delta are relevant for adaptation measures? Is it because it is an ecosystem relevant to agriculture and food security? Is it because a large population depends on the river? Is it because of the biodiversity? Is it because of all these factors? Do these links increase the coordination needs?
It is all of these factors, and the important point is that they are deeply interconnected. The Mekong Delta is one of the world's major agricultural and aquaculture regions, supports about 18 millions of livelihoods, and contains highly valuable freshwater, coastal and wetland ecosystems. Changes in river flow, sediment supply or salinity therefore have consequences not only for ecosystems, but also for food production, freshwater availability, infrastructure and household incomes.. These connections make coordination particularly important. A decision made upstream about hydropower or sediment retention can affect water and sediment conditions hundreds of kilometres downstream. Likewise, local decisions concerning groundwater extraction or sand mining can have consequences beyond the immediate extraction site. The Mekong therefore requires coordination across scales, from local communities and provinces to national governments and the wider basin.
Was the Mekong River one of the first examples of cooperation between countries to define transnational nature-based adaptation measures? Why?
I would be careful about describing the Mekong as one of the first examples specifically of transnational nature-based adaptation. The basin certainly has a long history of transboundary cooperation. The Mekong Committee was established in 1957, and the Mekong River Commission was established in 1995, providing an institutional framework for cooperation among Cambodia, Lao PDR, Thailand and Vietnam. However, the early focus was primarily on water resources, development and navigation rather than what we would today call nature-based adaptation. The concept has evolved. Today, maintaining sediment connectivity, restoring wetlands and mangroves, and allowing more natural river and floodplain processes are increasingly recognized as components of sustainable basin management. The key lesson is that adaptation in a transboundary river cannot be managed solely within national borders.
Where is the funding coming from? Are there financial pools to which different countries contributed? Which country contributed the most? How to define contributions on a theoretical perspective?
Funding for Mekong adaptation and research comes from a combination of national governments, international development agencies, multilateral development banks, research institutions and bilateral or multilateral programmes. The World Bank and Asian Development Bank, for example, have supported infrastructure, environmental management and regional development initiatives in the Mekong region over the years.
I would be cautious, however, about identifying a single country as the largest contributor without looking at a specific funding programme and time period. More fundamentally, contributions should not be viewed only in financial terms. A fair framework could consider a country's capacity to pay, its historical contribution to environmental pressures, the benefits it receives from basin development, and the downstream or transboundary consequences of its activities. This becomes particularly important when discussing sediment, hydropower, and climate adaptation because the costs and benefits are distributed very unevenly across the basin.
Are these financial pools also helping research? What are the political and practical structures allowing research activities there? Are these structures mostly connected to universities?
Yes. Research funding is an important component of the broader Mekong governance landscape, supporting environmental monitoring, hydrological modelling, remote sensing, field research, capacity building and science–policy engagement. Universities and research institutes play an important role, but they are only one part of a larger network that also includes government agencies, intergovernmental organizations, development banks and international research programmes. One important lesson from the Mekong is that research becomes much more useful when it is connected to decision-making structures. For example, our work combines satellite observations, field measurements and modelling to quantify processes such as river incision by riverbed sand mining, sediment loss, groundwater change and salinity intrusion. Recent studies have increasingly moved beyond simply documenting environmental change toward quantifying the contribution of specific pressures, which makes the science more useful for management decisions. For instance, research programs at the Earth Observatory of Singapore (EOS) at NTU rely on competitive funding to collect the biophysical, geospatial, and socioeconomic data required to inform sustainable river management policies.
What’s your relationship with local communities?
Our relationship with local communities is essential because remote sensing and modelling can tell us where environmental changes are occurring, but they cannot by themselves explain how those changes affect people's lives. Field observations and engagement with local stakeholders, which have been carried out annually, help us understand how farmers, fishers and other river-dependent communities experience changes in water availability, salinity, flooding, erosion and land conditions.
This interaction also works in the opposite direction: local knowledge can help researchers identify processes or changes that may not be obvious from satellite data alone. Ultimately, adaptation measures have to be scientifically sound but also socially and economically workable. Local ownership and participation are therefore important if recommendations are to move beyond academic findings and become practical solutions.
How have the research projects practically contributed? Could you provide some examples of that?
One important contribution of our research has been to provide quantitative evidence about processes that were previously difficult to separate or measure. For example, our recent counterfactual modelling by Kumar et al. (2026) shows that sand mining in the Mekong Delta exceeds natural sediment supply by several times and contributes substantially to riverbed incision and salinity intrusion. We estimate that sand mining accounts for roughly 25–30% of total channel incision and 16–30% of the annual increase in salinity under the modelled conditions. Our more recent review paper by Park et al. (2026) and groundwater research by Cheng Cheng et al. (2026) also extend the understanding of sand mining beyond river morphology. Our works indicate that mining-induced riverbed incision can alter surface-water–groundwater interactions, contributing to groundwater decline and reducing hydraulic connectivity between rivers and aquifers. Also, sand mining strongly impacts on ecological and social aspects. These findings provide a stronger scientific basis for discussing sand-mining regulation, surface-groundwater management, and sediment conservation in multiple aspects together rather than as separate issues.
How long does it take to implement policies/measures defined at a university level? What’s the process? What’s “special” about this in the Mekong River? Why?
There is no fixed timeline. Moving from research to policy can take years because scientific evidence must be translated into policy options, considered by relevant agencies, reconciled with economic and social priorities, funded, and eventually implemented and monitored. Even when the scientific evidence is strong, implementation depends on institutional capacity and political priorities. The Mekong adds another layer of complexity because it is a transboundary system. A measure that benefits the downstream delta may require changes in activities upstream, such as hydropower operation or sediment management. This creates a scale mismatch between where an environmental problem is experienced and where some of its drivers originate. At the same time, some pressures, particularly sand mining and groundwater extraction, can be addressed locally and nationally much more quickly. This is why our work emphasizes locally actionable measures while longer-term basin cooperation continues.
How to balance hard infrastructure, such as dykes and seawalls, with nature-based solutions such as wetlands and mangrove restoration?
I would not frame this as a choice between hard infrastructure and nature-based solutions. Both have a role, but they should be applied according to the level of risk and the characteristics of each location. Dykes, seawalls and other engineered structures may remain necessary around densely populated areas, cities and critical infrastructure where the consequences of flooding are severe. However, relying exclusively on hard infrastructure can disconnect rivers from floodplains and constrain the delta's ability to respond naturally to changing conditions. Nature-based measures such as wetlands, floodplain restoration and mangrove conservation can provide flood and erosion protection while also supporting biodiversity, fisheries and carbon storage. The most resilient approach is therefore likely to be a hybrid strategy, with engineering used selectively and natural processes protected wherever possible.
Is the switch from rice monoculture to rice-shrimp farming something that happened just in the region?
Rice–shrimp farming is particularly prominent in the Mekong Delta, especially in coastal areas where increasing salinity has made year-round freshwater rice cultivation more difficult. It represents an adaptation to seasonal changes in water quality and salinity rather than simply a technological replacement of one crop with another. I should further note that rice monoculture was common in the history, when there was low food demand and rice-shrimp farming was switched to help farmers to earn more income with adaptation and resilience to climate and environmental changes. However, the underlying idea is not unique to the Mekong. Similar transitions toward brackish-water aquaculture, salt-tolerant crops, and diversified farming systems have occurred in other deltas and coastal regions experiencing salinization. What is distinctive in the Mekong is the very large scale and the way rice–shrimp systems have become integrated into local livelihoods and agricultural economies. More broadly, the important principle is to align production systems with the hydrological conditions of a particular landscape rather than attempting to maintain the same production system everywhere.
In general, do you think changing crop patterns is a more sustainable adaptation strategy than continuing to intensify rice production?
In many areas, yes—but I would avoid treating crop diversification as a universal solution. Where salinity, drought, or water scarcity are becoming persistent, trying to maintain intensive freshwater rice production can require increasing amounts of freshwater and groundwater. That can create a feedback loop in which agricultural intensification contributes to groundwater depletion and subsidence, while the resulting environmental change makes agriculture even more difficult. A more sustainable approach is therefore to match agricultural systems to local hydrological conditions. Depending on the location, this could involve rice–shrimp systems, seasonal aquaculture, salt-tolerant crops, less water-intensive agriculture, or maintaining areas for natural ecosystems. The objective should not simply be to produce more rice, but to maintain long-term livelihoods and food security without undermining the physical foundation of the delta.
How can your experience with this and other adaptation measures help in other regions? Can the Mekong River help with water management, for instance? Just in specific geographies?
The Mekong is valuable as a global case study because it illustrates how climate change interacts with other human pressures, including dams, sand mining, groundwater extraction and agricultural intensification. What is transferable is not necessarily a specific intervention, but the analytical framework: combining satellite observations, field measurements and process-based modelling to understand how multiple pressures interact. For example, our recent modelling framework separates the effect of sand mining from other drivers under otherwise identical conditions. This type of counterfactual approach can be applied to other large river deltas where multiple pressures make it difficult to identify the contribution of individual drivers. The lessons are therefore potentially relevant to other Asian (i.e., Yangtze Delta, Ganges-Brahmaputra-Meghna Delta) and African (i.e., Nile Delta, Niger) deltas, as well as major river systems such as the Amazon (South Ameria), although adaptation measures must always be tailored to local geography, governance and livelihoods.
Could regulating sand mining be considered a climate adaptation measure, rather than only an environmental management measure?
Absolutely. Intensive sand mining physically deepens the riverbed, which structurally facilitates the deeper inland intrusion of saltwater from the ocean, while severely exacerbating riverbank erosion. Because sand mining directly amplifies the worst impacts of sea-level rise and worsens delta subsidence, aggressively regulating and restricting it is one of the most immediate and effective climate adaptation measures policymakers can enact.
How important is maintaining sediment flow for the long-term resilience of the Mekong Delta?
Maintaining sediment supply is fundamental to the physical sustainability of a delta because deltas depend on sediment deposition to compensate for natural compaction, erosion and relative sea-level rise. In the Mekong, upstream dams have already substantially reduced sediment delivery, while sand mining removes additional sediment directly from the river system. Studies estimated that upstream dams had reduced sediment delivery by roughly up to 70–83%, with potentially greater reductions if planned development proceeds. But I would not describe sediment flow as the single factor determining the delta's future. Resilience depends on the interaction of sediment supply, water discharge, land subsidence, sea-level rise, groundwater extraction, sand mining, and land-use decisions. The key is to restore or maintain sediment connectivity while simultaneously reducing the processes that accelerate elevation loss.
Could you also explain the role of mangroves?
This is not in my field and study focus. I can understand that mangroves are an important component of coastal adaptation because their roots stabilize sediments and their vegetation can dissipate wave energy, helping reduce coastal erosion and storm impacts. They also provide habitat for fisheries, support biodiversity, and store substantial amounts of carbon. These multiple benefits make mangrove conservation particularly valuable in a delta where environmental and livelihood systems are closely connected. However, mangroves should not be viewed as a substitute for maintaining the delta's sediment supply. Mangroves can trap and stabilize sediment, but their capacity to keep pace with rising sea levels and coastal erosion depends partly on whether sufficient sediment is available. In other words, mangrove restoration works best as part of a broader strategy that maintains sediment and allows coastal ecosystems sufficient space to adjust.
The Mekong Delta faces climate change alongside hydropower development, sand mining, groundwater extraction, and rapid agricultural development. How should policymakers distinguish between climate adaptation and adaptation to these other human-induced environmental pressures?
Policymakers must recognize that human-induced environmental pressures—such as upstream dams and intensive sand extraction—are currently reshaping the river and destabilizing the delta at a much faster rate than global climate change alone. While global climate adaptation requires massive international coordination on carbon mitigation, adapting to human pressures requires immediate, enforceable local and regional regulations. Attributing delta degradation solely to climate change allows regional actors to deflect accountability for unsustainable extractive practices.
In conclusion, are there any other considerations to make about climate adaptation measures in the area? What could be improved?
The most important consideration is to stop treating the Mekong Delta as an isolated downstream problem. The delta is part of a connected river basin, so its long-term resilience depends on water, sediment and ecological connectivity across national boundaries. At the same time, we should not wait for perfect basin-wide cooperation before acting. Some of the most effective measures, such as reducing excessive groundwater extraction, tightening sand-mining controls, improving water-use efficiency and protecting natural ecosystems, can be implemented locally and nationally. I would also emphasize that adaptation should be measured not simply by how well we protect today's infrastructure, but by whether we maintain the delta's capacity to function in the future. That means combining selective engineering with nature-based approaches, adapting agricultural systems to changing water conditions, maintaining sediment connectivity, and improving monitoring and enforcement. The fundamental shift is from trying to control every aspect of the delta toward managing the pressures on it and working with its natural processes.
