Ho Chi Minh City Grapples with Rising Floods Amidst Climate Change

Ho Chi Minh City, one of the world's most climate-vulnerable cities, is facing escalating flood risks due to the combined effects of climate change, rapid urbanization, and land subsidence. On September 30, high tides merged with heavy rainfall, causing the Saigon River and its tributaries to overflow into the streets of Vietnam's commercial hub. Residents in low-lying areas have adapted to regular flooding, with some elevating their homes, but the disruptions remain significant.

Benjamin Horton, a professor of earth science at City University of Hong Kong, explained that climate change exacerbates flood risks by increasing sea levels and intensifying rainfall. These changes can overwhelm the city's drainage systems, particularly in densely populated areas. Much of Ho Chi Minh City's land is less than a meter above sea level, and its original drainage and canal system, built during the French colonial era for a population of 2 million, now struggles to cope with the city's rapid growth.

Adding to the vulnerability, parts of the city are sinking due to excessive groundwater extraction. This phenomenon, known as land subsidence, causes the ground to compact and sink as water is removed from underground layers. The consequence is increased risk for residents, with floodwaters inundating homes and businesses, disrupting transportation, damaging infrastructure, and potentially contaminating water supplies, thus raising public health concerns.

For business owners like Nguyen Ngoc Thuong, who runs a small eatery, floodwaters can reach knee-height during high tides or heavy rain. "It takes more than two hours for the water to go down. Some customers just walk through the water and sit down to eat," she noted.

In response to these challenges, Vietnam is pursuing an economic overhaul aiming for high-income country status by 2045. Ho Chi Minh City has been expanded through mergers with neighboring provinces, creating a megacity with diverse landscapes and urbanization levels. Authorities recognized that the existing drainage infrastructure, approved in 2001 and 2008, was inadequate for the expanded city.

In July, a $13 billion plan was launched to address 159 flood hot spots by 2030, which includes upgrading flood-control infrastructure. The city also adopted a climate action plan through 2030 to enhance drainage systems, expand green spaces, and improve resilience to heavy rain, high tides, and rising sea levels.

Horton emphasized that the problem is multifaceted. Rising sea levels impede the drainage of rainwater into the sea, while heavier rainfall increases the volume of water entering the city rapidly. In a sinking city, water accumulates faster and recedes more slowly. As global temperatures rise, floods that were once rare are becoming more frequent, deeper, and longer-lasting.

This trend is observable across the region. In mid-September, heavy rains in Thailand affected over 2.6 million people and caused at least 19 fatalities.

Meanwhile, residents like Nguyen Thi Nhua continue their daily lives, selling their goods from sidewalk stalls, even as floodwaters rise. "There are still customers who stop by, so I just keep my stall open when it rains or the tide comes in," she said, reflecting the resilience of those living in flood-prone areas.