- Hat Yai’s economy is still struggling to recover from the devastating November 2025 floods, raising fears that repeated disasters could drive businesses and investment away from the southern Thai tourism hub.
- Flood risk is rising due to urban expansion, altered drainage, upstream land-use change and increasingly intense rainfall linked to climate change.
- Decades of costly engineering fixes have failed to keep pace, and without major land-use reforms and nature-based solutions, the city risks locking itself into a cycle of worsening floods.
- This post is an analysis. The views expressed are those of the authors, not necessarily of Mongabay.
Every year, Chinese New Year festivals in southern Thailand’s Hat Yai attract tourists, mostly from neighboring Malaysia, generating a significant proportion of annual income for a city dependent on tourism.
But not this year.
Three months after the November 2025 flood disaster, the new year is being celebrated with continuing cleaning, scrubbing mud from people’s homes and shops, and clearing away piles of water-damaged vehicles, furniture and rotting rubbish. More than 40% of hotels, shops and restaurants remain shut. Some might not reopen at all.
It’s not just about cleaning up and reviving the city with festivals, but convincing businesses and the private sector to stay in the largest economic hub in southern Thailand. The business sector is still reeling from the effects of COVID-19 lockdowns. Somporn Siriporananon, a former vice president of the Chamber of Commerce of Songkhla province, where Hat Yai is located, said he’s extremely anxious about the slow recovery.
“The business sector doesn’t have the confidence to invest in recovery or new ventures,” he said. “The risk of another large flood is too high and there is a general feeling it might not be worth it. This is especially the case for the SMEs [small and medium-sized enterprises].”
Such apprehension is understandable. In the last 40 years, Hat Yai has experienced four major flood disasters, each more costly and deadlier than the last. The 1988 disaster caused losses of 4 billion baht, or about $158 million at the exchange rate back then. The 2000 and 2010 floods each caused losses of 17 billion to 18 billion baht ($423 million to $568 million at contemporary exchange rates).
The most recent disaster, last November, left a death toll of 170 and is estimated to have cost 20 billion to 25 billion baht ($618 million to $773 million). The Thai government’s Geo-Informatics and Space Technology Development Agency (GISTDA) estimates a cost of 1.2 billion baht ($37 million) just to repair inundated houses within Hat Yai municipality, one of five that make up the wider Hat Yai–Songkhla metropolitan area. Somporn said the indirect effects of the floods, through sluggish recovery and business shutdown, could push the actual losses to 300 billion to 400 billion baht ($9.2 billion to $12.3 billion).
Hat Yai is especially vulnerable to flooding. It lies in a low-lying floodplain, widely described as a frying pan, into which two river systems, the U-Thapao and Sadao, flow before draining out into the Songkhla Lake Basin. The wider Hat Yai urban region has expanded dramatically in recent decades and now encompasses a total area of 1,200 square kilometers (460 square miles). This expansion has intensified despite the most recent urban development and land zoning plan dating back 14 years, since just after the last flood disaster. Much of the expansion has been against the natural flow of water, filling in the floodplain, and constructing roads that block drainage.
As Hat Yai’s urban area grows, the flood risk is intensifying. Much of the upper catchment in the wider basin has been converted to rubber plantations. Songkhla Lake into which the floodwaters drain has also become progressively shallower, due to sedimentation and erosion. Moreover, with climate change, the monsoon season is getting wetter and extreme rainfall events are occurring more frequently. Hat Yai could face another flood disaster, as soon as in five years’ time, but also potentially this coming rainy season.
The history of hard infrastructure solutions
Since last November’s disaster, there’s been much discussion on ways to mitigate and prepare for future floods. A broad range of measures and approaches — improving flood modeling, strengthening early-warning systems (EWS) and supporting institutional coordination to implementing more effective land-use planning — have been discussed.
Historically, Hat Yai has relied on hard infrastructure to improve the drainage that the patterns of urban expansion have undermined. Each disaster prompted investments in constructing large-scale drainage or levee systems, with the promise that such infrastructure would protect the ever-expanding city. However, these interventions have failed in each of the major floods.
The primary flood infrastructure protecting Hat Yai is Khlong R.1, a canal constructed to divert some water from the U-Tapao River to drain more quickly into Songkhla Lake.
Khlong R.1 was first constructed in response to the 1988 flood disaster. After the 2000 flood disaster, Khlong R.1 was widened to increase the flow capacity to 465 cubic meters per second (16,421 cubic feet per second), costing more than 2.7 billion baht (about $64 million at the time).
Yet even the widened Khlong R.1 was still inadequate. In response to the 2010 disaster, an investment of 5 billion baht ($158 million at the time) was made to increase the canal’s flow capacity to 1,200 m3/s (nearly 42,400 ft3/s). Another 5 billion baht was allocated for constructing five reservoirs and a 22-kilometer-long (13.7-mile) drainage canal running in parallel to Khlong R.1 in the second phase, which was completed in 2022.
Each upgrading of Khlong R.1 was designed to meet the previous disaster. In the same period that Khlong R.1 was being upgraded, the urban area of Hat Yai continued to expand. The current flow capacity of 1,200 m3/s was based on the 2010 disaster. But 15 years ago, the climate regime and land-use patterns were different from those that prevail today in Hat Yai. The construction of Khlong R.1 also generated a sense of security and encouraged further expansion of housing and commercial properties in the area that the canal was designed to drain.
In addition to these canals, a system of 19 pumps is also in place to provide additional drainage capacity during a flood event. Powered by diesel, the operation of these pumps requires an enormous budget; in 2025, only five pumps were operational.
The focus on engineering solutions also involves reframing existing infrastructure plans for urban expansion as contributing to flood protection. Most significantly, only two days before the 2025 flood began, the Department of Highways announced its plan for a 66-km (41-mi) ring road that was originally designed to encourage the further expansion of the city and enhance cross-border road logistics, as a barrier that will improve flood protection for the expanding urban area. Running along the side the road will be a canal, 50 m wide by 4 m deep (164 by 13 ft). With the inclusion of what’s being called a waterway, the ring road has been touted as a mechanism to improve drainage by driving floodwaters away from the city and toward Songkhla Lake. In this way, the ring road will act as a levee protecting the urban area from floodwaters coming from outside the city.
With many years’ experience working in Hat Yai, Thongchai Roachanakanan, a senior climate change and flood expert who recently retired from the Department of Public Works and Town and Country Planning, said it may have the opposite effect.
“As far as I can see, this ring road project will change the natural drainage pattern vastly,” he said. “Moreover, the project will stimulate urban development along the new road. Certainly, many housing developments will come first followed by a number of commercial investments. In short, the larger urban area of Hat Yai will block the natural drainage system completely.”
Hat Yai is on course to become the second-largest metropolitan area in Thailand, after Bangkok and ahead of Chiang Mai, with plans for a special economic zone in neighboring Chana district and road and rail links to Malaysia. With a budget of 12 billion to 13 billion baht ($370 million to $400 million) and construction due to begin in 2027, the real drive behind the ring road appears to be to promote exactly the kind of urban growth that has been a major factor in intensifying Hat Yai’s flood risk. Ironically, in 2025, as the inner city flooded, one of the suggestions discussed in Thai media was to blow a hole in the existing Road 414 to accelerate the drainage of the floodwaters from the inundated city.
Building such a road-levee systems creates additional risks. The experience of Hat Yai and similarly vulnerable cities around the world also points to the risk of catastrophic flooding should the levee system fail. And of course, if flooding occurs because of direct rainfall within the city rather than runoff from the wider catchment, the road will trap the water, further intensifying the impacts of the flood.
Nature-based solutions
In response to the limitations of gray infrastructure to deal with climate-related flood risk, across the world there’s growing interest in nature-based solutions (NbS): interventions to rehabilitate natural systems that contribute to improved drainage and flood protection. The repertoire of NbS technologies includes familiar actions, such as reforestations in upstream areas, restoring wetlands, reconnecting floodplains, rewiggling rivers and replanting coastal mangroves. A critical feature of NbS is that they’re implemented at the landscape scale, often covering multiple ecosystems, while delivering benefits for both people and nature.
Within the grand ambitions for the Ha Yai metropolitan region, beyond the ring road and waterway, the main NbS is leaving the districts by the lake as flood-retention areas, facilitating drainage from the growing city.
Chakrit Bhocharuang, from the Songkhla Community Foundation, a local civil society organization supporting early-warning systems and disaster response, supports the idea of integrating softer, more natural infrastructure approaches into development of new urban areas and flood mitigation.
“The flood has destroyed confidence in flood protection and compels people to think about land-use planning again,” he said. “We need a city ecosystem with improved green space and road systems that can handle flooding.”
Nature-based approaches pose questions for cities like Hat Yai that have been built in areas that by nature are prone to flooding. For Hat Yai, NbS are a means of retrofitting a city that has grown against nature. With so much of the natural drainage of Hat Yai and the wider landscape already dramatically refashioned, reclaiming natural drainage channels and flood retention areas would inevitably require relocating housing and businesses, with the associated costs and challenges of doing so in ways that are just and equitable.
For Chakrit, these are institutional, political and economic challenges. The main obstacle to implementing NbS in Hat Yai, he said, “is a planning problem and there’s no incentive for local authorities to work together on this scale. As a result, hard infrastructure projects will always be prioritized.”
For effective flood protection, large-scale nature-based approaches, preferably at the Songkhla Lake Basin level, would be needed. Currently there’s no real administrative or institutional framework to operate at this scale. For each of the local authorities within the Hat Yai urban area, the main incentive that drives land-use planning is to maximize direct economic benefits, which itself depends on expansion and construction. Even collaborating across local authorities for a comprehensive city plan has proved difficult due to these competing interests. The potential for even greater cooperation for NbS seems limited.
Conclusion
That Hat Yai is vulnerable to flooding has long been recognized, and in many ways is a statement of the blinding obvious. A city located in a low-lying recession in a floodplain is inevitably vulnerable. But with a history of intensifying flood disasters with ever-growing impacts on people and the economy, Hat Yai is at a critical juncture. Further growth along the lines of the past would appear to be less viable. However, forging an alternative pathway is also enormously challenging, and would require correcting the land-use planning failures of the past, and planning at an ecological scale — for which there is no precedent in Thailand.
Banner image: Flooding in HaT Yai, November 2010. Image by Government of Thailand via Wikimedia Commons (CC BY 2.0).
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