Building Saigon River islets could destroy local balance

Almost all scientific methods are based on observations of natural rules and phenomena. This lesson was taught to me upon first learning about research methodology. I continued to teach this lesson to future generations of researchers in France, where I am currently teaching.

Young generations in France are now very concerned about limiting the forceful impacts of humans on nature. For example, due to mass urbanization over the past few hundred years, many rivers and streams in the southeast region of France have been replaced by sewer systems, has led to worsening droughts in the dry season, and floods in the rainy season. The French regret the mistakes they have made in the past, especially with regard to their natural environment.

Teaching these young students in France made me reflect on my hometown, Ho Chi Minh City, which was once dubbed the "Pearl of the Far East."

Recently, a consulting joint venture between the Association of Vietnamese Scientists and Experts, a Paris-based strategic consulting firm, and L’Institut Paris Region, the oldest and largest urban planning agency in France, proposed the construction of small-garden islets in the middle of the Saigon River, one of HCMC’s main waterways. The proposal, as submitted to the HCMC Department of Planning and Architecture, though showing some prospects towards a modern city, looked rather narrow and stuffy to me.

An artist's impression of pedestrian bridges connecting with garden islands on the Saigon River. Photo courtesy of the French consulting consortium

Water surfaces play a crucial role in regulating temperatures in the city. Large water surfaces like rivers and lakes help store rainwater, which not only helps the city with drainage issues after large downpours, but also helps the city cool down and maintain a steady temperature.

The Saigon River is a vital part of temperature regulation in HCMC, a city with high temperatures year-round. The width of the river passing through the city is approximately 200 meters. If local authorities decide to construct small islets on the Saigon River, these slices of land will fragment the water surface area, which could then decrease by 30%.

After the small islet construction, on paper, the water surface of the Saigon River would be approximately that of the Seine River in Paris, with some natural islets. However, in reality, the two rivers would be fundamentally different.

First, the islets in the Seine River are built on natural ground, which still absorbs water, unlike concrete-built artificial islets. During rainfalls, these islets in the Seine River still help to transfer the water underground, while THE concrete-built islets proposed for the Saigon River would be unable to serve this function.

Second, there is a larger distance between the water to the bank on the Seine River compared to the Saigon River, which is better for drainage. Therefore, if not calculated carefully, small islets could choke the Saigon River’s water drainage mechanism and flood the city whenever it rains.

Additionally, all the small islets in the Seine River are naturally constructed after thousands of years thanks to water flows, while the streams in the Saigon River would be artificially altered by the small islets.

The Saigon River passes through various provinces, including Binh Phuoc, Tay Ninh, and Binh Duong, before ending up at HCMC and joining with the Dong Nai River. With the construction of small islets, Saigon River’s stream would be significantly altered, which could result in land erosion.

Globally, there have been various artificial islands and islets constructed on large rivers all over the world.

Some well-known examples include the 200-meter-width Seonyudo and Nodeulseom small islands on the 800-meter Han River, Seoul. Instead of building completely from scratch using artificial concrete, these islands were built atop small, natural sand dunes and rocks in the middle of the river.

The Little Island on the west coast of Manhattan (New York, U.S.) was constructed and became a 0.97 square hectare park in the middle of the Hudson River, with a width of over 1,000 meters.

The construction of islands on the Saigon River would have more detrimental effects on HCMC than similar construction projects in other countries. This is due to the high temperature of HCMC, averaging at 26 degrees Celsius year-round. Other countries have lower temperatures, such as Paris, where temperatures range only from 14 to 26 degrees Celsius in the summer. The difference in average temperatures between HCMC and Paris suggests that any reduction in water surface in HCMC would exaggerate the already boiling atmosphere in the city.

Realistically, with the heat in HCMC, no individual would venture for a walk outside to enjoy the islets, which defeats the purpose of the project.

Learning from foreign countries is good, but it should be done selectively. There are different ways that local authorities of HCMC could learn from Paris regarding the commercialization and development of its main rivers. One of these ways is waterway tourism, which brought in over 40 million euro in revenues for Paris in 2023, without the risks of increasing the city’s heat.

The development of the Saigon River is a socio-economic problem with natural constraints. The optimum solution for this type of problem usually comes from detailed research and respecting natural laws, while striving to minimize the forceful impacts of humans on nature and facilitate sustainable development.

Simply copying the solutions of other countries and territories without carefully considering the natural characteristics of terrains, weather, and environment could lead to improper interventions and lasting damages.

*Vo Nhat Vinh is an R&D expert based in France.