Why Vietnam Needs Both Concrete and Nature to Fight Floods

Flooding is becoming one of Vietnam’s most pressing environmental and economic challenges. According to the World Bank, floods and other climate-related disasters cost Vietnam an estimated 1 to 1.5 per cent of GDP annually, with these losses expected to rise as climate risks intensify. Across the country, rising sea levels, more intense rainfall and rapid urbanisation are increasing pressure on existing flood protection systems. These systems include floodwalls, levees, drainage networks, embankments and tidal flood-control gates, many of which are increasingly strained by rapid urbanisation and climate change. In Ho Chi Minh City (HCMC) alone, more than half of the city’s land lies below 1.5 metres above sea level, leaving large areas highly exposed to tidal and pluvial flooding despite extensive flood-control investments.

In response, researchers, planners and international organisations increasingly promote Nature-based Solutions (NbS), including Blue-Green Infrastructure, Sponge Cities, wetland restoration and mangrove rehabilitation. In Vietnam, these approaches are often promoted for multiple objectives, including ecosystem restoration, carbon sequestration and climate adaptation, with flood mitigation being one of several anticipated benefits. These approaches can help manage floodwaters while delivering environmental, social and climate-related benefits.

On paper, the argument appears compelling. Yet Vietnam’s largest cities continue to invest heavily in floodwalls, flood gates, embankments and drainage systems. In HCMC, the city’s flagship tidal flood control project is estimated to cost nearly VND10 trillion (about USD430 million), illustrating a continuing reliance on large-scale engineered solutions to protect urban areas from increasing flood risks. This raises an important question: If nature-based solutions are so promising, why does Vietnam still rely on concrete-based flood defences such as floodwalls, levees and embankments to protect its cities?

The answer is more nuanced than many flood adaptation debates suggest. In dense urban environments, the main barriers are not just political or institutional, but often physical, economic and structural. Many discussions about flood management focus on technical performance: Can a wetland store more water? Can a retention basin reduce peak flood levels? Can green spaces improve drainage?

These questions are important. However, flood adaptation is not simply about moving water. It also involves economic activity, urban development and public confidence. Infrastructure such as floodwalls and levees often provide benefits beyond flood protection, safeguarding land values, supporting development and attracting investment.

As a result, replacing or reducing grey infrastructure is rarely a purely technical decision. Developers may face restrictions on future projects, governments may need to sacrifice valuable urban land for flood retention and communities may be concerned about the economic and social consequences of land-use changes. This is one reason why many climate adaptation projects encounter political and institutional resistance even when their environmental benefits are widely recognised.

Many NbS require land. That land may already be used for housing, development, infrastructure or agriculture. In rapidly urbanising areas such as HCMC and the Mekong Delta, land is increasingly contested between adaptation and development.

This helps to explain why Vietnam’s largest cities have increasingly pursued engineering-based responses to flooding. Hanoi has invested in underground stormwater reservoirs to temporarily store floodwaters during heavy rainfall, while HCMC has built flood-control gates and embankments to address tidal flooding and storm surges.

These projects do not necessarily reflect a rejection of NbS; rather, they recognise that in dense urban environments, land is limited and flood risks require immediate responses. More broadly, these examples highlight an oft-overlooked reality: successful flood adaptation requires balancing environmental benefits with economic and social interests. When communities, developers or governments perceive that they are losing benefits associated with existing infrastructure, resistance can emerge even when long-term climate outcomes are positive.

This does not mean NbS are ineffective. Instead, it suggests that their greatest potential may lie in peri-urban areas, river corridors and ecosystem restoration projects where land constraints are less severe, such as the peri-urban districts surrounding HCMC, the Mekong Delta’s floodplainsand mangrove restoration areas along Vietnam’s southern coastline.

Countries such as the Netherlands are frequently cited as global leaders in flood management. Projects such as Room for the River demonstrate how engineering and natural systems can be integrated to improve resilience while creating environmental and recreational benefits.

These projects provide valuable lessons. However, successful adaptation strategies cannot simply be transplanted. The Netherlands operates within a different governance, planning, economic and land management context. Vietnam faces its own challenges, including rapid urbanisation, competing development priorities, population growth and increasing exposure to climate-related hazards. Thus, a strategy that succeeds in Rotterdam may not automatically succeed in HCMC or the Mekong Delta.

For countries such as Vietnam, hybrid approaches may offer a more realistic pathway than replacing existing flood-defence systems.

Across Asia, governments increasingly look abroad for climate adaptation solutions. Yet successful solutions depend on local governance, economic incentives and development priorities. The goal should not be to copy international models, but to adapt useful lessons to local conditions.

Too often, flood management debates are framed as a choice between grey and green infrastructure. Rather than asking whether floodwalls should be replaced by nature-based solutions, policymakers should ask how both approaches can complement one another. For example, future floodwalls could be designed with provisions for future height increases as sea levels rise. Levees could be integrated with public open spaces and ecological corridors.

Urban developments could incorporate retention areas, permeable surfaces and water-sensitive design features alongside conventional drainage systems. These hybrid approaches may be more politically acceptable, economically feasible and socially supported than attempting to entirely replace existing infrastructure.

For countries such as Vietnam, hybrid approaches may offer a more realistic pathway than replacing existing flood-defence systems. Most importantly, they recognise that cities must continue functioning while adapting to a changing climate. Vietnam’s flood future is unlikely to be entirely ‘green’, nor is it likely to remain entirely ‘grey’.

The challenge is to design solutions that acknowledge current economic and social realities while preparing for future climate risks. Vietnam has invested heavily in flood protection, yet many cities remain caught in a cycle of responding to worsening floods with ever-larger engineering projects while climate risks and urban pressures grow. NbS have an important technical role to play in Vietnam’s flood resilience, but their success will depend on whether NbS can be integrated into existing systems while maintaining economic opportunities and community support.

The most realistic future may be one in which engineering and nature work together. The broader lesson extends beyond Vietnam. Across Southeast Asia, governments face growing pressure to adapt to climate change while maintaining economic growth and urban development. The challenge is not identifying what works in theory, but aligning environmental goals with local realities.

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