Ho Chi Minh City’s severe land subsidence heightens flood risks: study

Studies presented at a seminar organized by the University of Natural Resources and Environment in late August showed that the city is sinking at an average rate of two to five centimeters per year.

In areas with weak geological foundations, particularly zones with dense commercial developments, subsidence is accelerating, reaching seven to eight centimeters per year.

The most affected areas lie along the Saigon River, from the Saigon Bridge to Ba Son Bridge, as well as in the southern part of the city.

A November 2024 report from the Ho Chi Minh City Department of Agriculture and Environment noted that subsidence began around 1990.

Current rates now exceed twice the pace of sea level rise, which is about one centimeter per year.

Comparisons of measurements from 2005 and 2014 by the Department of Surveying, Mapping, and Geographic Information showed up to 10 centimeters of sinking over ten years in some locations.

Overall, land subsidence has impacted 239 square kilometers, with the most severe areas sinking 44 to 73.3 centimeters over the past decade.

The lowering of ground levels, combined with rising tides and heavy rainfall during the rainy season, has caused severe waterlogging, affecting residents’ daily lives and socio-economic activities, experts warned.

Assoc. Prof. Dr. Le Trung Chon, director of the Research Institute for Sustainable Development at the University of Natural Resources and Environment, said the combined effects of subsidence, climate change, extreme weather, and rising tides could severely damage infrastructure, residential areas, and socio-economic development.

He identified four main drivers of land subsidence in the city: weak geological foundations in southern areas, declining groundwater levels, transportation and construction activities, and rapid urbanization.

If Ho Chi Minh City does not implement timely countermeasures, it could face a situation similar to Jakarta, which has prompted Indonesia to relocate its capital to Nusantara on Borneo Island.

Currently, the city’s subsidence rate has even surpassed that of Jakarta, Dr. Chon warned.

Dr. Chon also called for early implementation of a ground deformation simulation and forecasting system to enable timely measures and rapid, accurate decision-making.

In response to severe subsidence, extreme rainfall, and rising tides, city authorities have developed a comprehensive flood prevention and wastewater treatment project spanning from 2020 to 2045, complemented by a focused plan for the 2020–30 period.

To date, rainfall-related flood mitigation has been completed on five of 18 main streets, while only one of seven major routes has seen improvements in managing tidal flooding.

The city is accelerating the first phase of its tidal flood mitigation project, with a budget of VND10 trillion (US$379.2 million), which is now 93.33 percent complete.

An anti-erosion project on the Thanh Da Peninsula is also underway to address remaining tidal flood points in the Binh Quoi area, alongside canal dredging, maintenance, and reinforcement initiatives at both local and city levels.