Heavy, continuous rains in 2025 have caused severe flooding in many areas of Hanoi, paralyzing traffic and disrupting residents’ daily lives.

As the urban drainage system reveals clear limitations under the pressure of urbanization and climate change, the solution to flooding cannot be limited to just increasing the capacity of sewers and pumping stations. A comprehensive approach is needed, spanning from planning and infrastructure to urban space.

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The flooding situation is not only occurring in traditional low-lying areas but has also spread to newly developed zones, which were expected to have synchronized infrastructure. The heavy rains this year are not just an extreme phenomenon of climate change but also point to gaps in Hanoi’s adaptive capacity.

Current temporary solutions often focus on improving drainage capacity. However, viewing flooding only from a drainage engineering perspective addresses just the symptoms of the problem. Reality shows that even when pumping systems operate at full capacity – as during the rain on September 30, 2025, when the Yen So Station operated all 20 pumps – there is still no way out. “When concrete overwhelms permeable surface areas, when ponds and lakes – natural ‘water reservoirs’ – are filled in to make way for high-rises, and when new urban areas inadvertently become artificial embankments blocking drainage paths, then flooding is the inevitable consequence of a development process that lacks respect for hydrological laws. It is time for Hanoi to adopt a new planning mindset; the city needs to ‘live with water’ rather than just ‘fight against water.'”

Sharing a similar viewpoint, it is recognized that the urban drainage system has not been invested in synchronously according to planning. The inner-city area covers over 313 square kilometers, but currently only about 77.5 square kilometers in the To Lich river basin have a relatively complete drainage system, accounting for less than 25% of the area. The Ta Nhue, Huu Nhue, and North of the Red River basins are still in the process of preparation or investment implementation.

According to leadership, the primary cause of flooding in Hanoi is rainfall far exceeding the system’s drainage capacity. Many rain events have an intensity nearly double the design capacity, causing the entire system to be overloaded. Additionally, water levels in rivers on Hanoi’s outskirts have risen above warning levels, including the Nhue River at the Thanh Liet dam reaching about 5.7 – 5.9 (higher than the planned control level of 4.5) and receding slowly. Meanwhile, the ground elevation in some urban areas and residential zones within the Ta Nhue and Huu Nhue basins is at a level of 5 – 5.5, making gravity drainage impossible and leading to waterlogging. The agricultural drainage system – which is a primary outlet for the city – has not been renovated to meet urban drainage requirements. Furthermore, many planned key projects, pumping stations, and regulating lakes have not been invested in or are not operating at full design capacity.

In addition, rapid urban development, lacking synchronization in ground levels between new urban areas and existing residential zones, along with internal drainage infrastructure not being effectively connected to the general system, has increased the risk of localized flooding.

Prolonged, high-intensity rainfall, combined with high tides and sea-level rise, has turned urban flooding into a systemic issue in Vietnam’s major cities. The traditional drainage system (gray infrastructure) is gradually revealing its limitations under the pressure of urbanization and extreme weather. In this context, urban green spaces need to be reconsidered as a core component of green infrastructure.

Unlike the traditional view that sees greenery merely as decorative, modern urban planning views green spaces as a sustainable stormwater management solution. Green spaces perform many important hydrological functions, helping to reduce surface runoff and regulate rainwater.

Organizing urban green spaces not only meets landscape and aesthetic requirements but is also an important strategy for cities to adapt to flooding and climate change. Green space planning must move beyond mere landscaping to become a core component of green technical infrastructure. Integrating drainage and rainwater regulation functions into the structure of green spaces will help create hydrological buffer zones capable of infiltration, water storage, and slowing surface runoff.

A new approach to flood prevention and control is proposed: retain water upstream, reduce flooding midstream, and prevent flooding downstream. Thus, the urban drainage system must

Hanoi

Hanoi is the capital of Vietnam, with a history spanning over a thousand years since its establishment as the capital of the Đại Việt kingdom in 1010. It is renowned for its well-preserved French colonial architecture in the Old Quarter, ancient temples like the Temple of Literature, and its pivotal role as the political and cultural heart of the country throughout various dynasties and modern conflicts.

To Lich river

The To Lich River is a historically significant waterway flowing through Hanoi, Vietnam, which was once a major tributary of the Red River and a vital part of the ancient city’s trade and drainage system. Over recent decades, it has become severely polluted due to urbanization and industrial waste, symbolizing the environmental challenges of rapid development. Efforts have been made to clean and restore the river, reflecting its enduring cultural and ecological importance to the capital.

Ta Nhue basin

The Ta Nhue basin is a river basin located in northern Vietnam, primarily within the Hanoi metropolitan area. Historically, it was a vital agricultural region, but in recent decades it has undergone rapid urbanization and industrialization, which has significantly altered its landscape and posed environmental challenges.

Huu Nhue basin

The Huu Nhue basin is a historical irrigation system located in northern Vietnam, primarily in the Red River Delta. It was originally constructed during the 18th century under the Later Le dynasty to provide water for agriculture and flood control for the surrounding regions. Today, it remains a vital part of the local water management infrastructure and a testament to traditional Vietnamese hydraulic engineering.

Red River

The Red River is a major waterway in North America, flowing roughly 1,360 miles from the Texas Panhandle through Oklahoma, Texas, Arkansas, and Louisiana into the Mississippi River. Historically, it was a vital trade and transportation route for Native American tribes and later for European settlers, forming part of the border between Texas and Oklahoma. Its name is derived from the reddish silt it carries from its basin, and it was the scene of significant 19th-century riverboat commerce and frontier conflicts.

Nhue River

The Nhue River is a major tributary of the Red River in northern Vietnam, flowing through Hanoi and Ha Nam province. Historically, it has been a vital water source for agriculture, transportation, and daily life for centuries, shaping the development of the ancient Red River Delta civilization. Today, it faces significant environmental challenges due to urbanization and industrial pollution.

Thanh Liet dam

The Thanh Liet Dam is a modern irrigation dam located in Thanh Tri District, Hanoi, Vietnam. It was constructed in the late 1970s to control flooding and provide water for agriculture in the southern part of the capital. Today, it serves as a vital piece of local infrastructure and has also become a popular scenic spot for nearby residents.

Yen So Station

Yen So Station is a modern metro station located in Hanoi, Vietnam, serving the city’s elevated Line 3 of the Hanoi Metro. It opened in 2021 as part of the Nhon-Hanoi Station metro line project, which was developed to alleviate the capital’s significant traffic congestion. The station’s name is derived from the nearby Yen So Park and historical Yen So Village, an area with centuries of local history.