Sifting through the mud and floods

Communities in Chiang Rai and Chiang Mai provinces have been hit by two waves of flooding in the past several weeks, with locals describing these as the worst floods in decades.
Although the floodwater in most areas has since receded, residents and volunteers are still clearing the sludge covering the streets and people’s homes.
The heavy flooding and its aftermath have left many pondering the factors that contributed to the disaster.
The Bangkok Post talked to experts in water management and engineering who suggested the authorities reconsider urban planning and seek collaboration with Myanmar to address future cross-boundary flood risks.
Change of land use
Thanapon Piman, a senior researcher at the Stockholm Environment Institute, said the flood that ravaged Mae Sai district of Chiang Rai province was unusual — not only for its frequency but also for the massive amount of mud it brought with it.
This could be attributed to the seasonal rainfall that began in August, combined with the influence of Typhoon Yagi, which brought heavy rain to Myanmar. The excess water, along with mud, flowed into the Mae Sai River, suggesting there was a change in land use in headwater areas.
Mr Thanapon said the mud had two sources: natural landslides and agriculture or mining in forest areas. Meanwhile, exposed topsoil became mud in the river.
“However, while there are no statistics on this, my assumption is the large amount of mud didn’t come solely from nearby areas,” he said. “Over 80% of it likely originates from the Mae Sai River watershed.”
The flood was not caused by the release of excess water from upstream dams in Laos and China as some thought, he said. Coping with future flood risks is a huge challenge, especially when the Thai side is located downstream.
In the short term, apart from rehabilitating flood-ravaged communities, opening water-level monitoring stations in the headwaters of the Mae Sai River is a must-do to serve as an early warning system, he said.
Next is developing a more efficient disaster response plan or improving city planning, Mr Thanapon said.
However, that would be an uphill task because the area is a special economic zone and people are unlikely to relocate. An evacuation plan should be in place to ensure those in risk-prone areas are safely evacuated during a flood.
In the long term, the central government must step in because local authorities do not have adequate resources to manage the situation — whether to restore flood protection barriers or improve water drainage capacity through the irrigation system.
Mr Thanapon stressed the need to foster collaboration with Myanmar, saying cooperation must be multi-dimensional, engaging communities, businesses and academic input.
This is a cross-border issue that affects both countries, and the area is not only under the control of the Myanmar government but also under the control of ethnic minorities and armed groups, he added.
“Managing water is easier than tackling the issue of mud, as the latter involves land use and requires much more time,” he said. “We need to persuade our neighbour to be aware of the soil erosion problem.
“Both sides also have a lot of work to do because there is no data on the amount of mud, which is essential for planning and decision-making,” he said.
Flood mitigation needed
Suchatvee Suwansawat, a former president of the Engineering Institute of Thailand, said the flooding was caused by global warming and human activities, such as deforestation and encroachment on riverbanks.
The issue requires a strong will from the government, particularly Prime Minister Paetongtarn Shinawatra, who must bring together state agencies to develop an urban plan and ensure it is strictly enforced to ensure sustainability, he said.
Mr Suchatvee said communities in water retention areas should be made aware of the situation and offered incentives to relocate.
“It happens every year, and how bad depends on the amount of water. If the government and the public do not cooperate, it will get worse each year,” he said.
Mr Thanapon said several buildings on the Thai side near the First Friendship Bridge obstruct the water flow and dismantling them could enable faster drainage and allow for the construction of flood barriers.
Regarding Mae Sai’s Sailom Joy Market, a border market severely hit by floods, he said if businesses are to remain in their current locations, the buildings must be at least two storeys high to allow occupants to move to the upper floors during a flood.
He admitted residents may struggle to finance renovations and the proposal may require the collaboration of multiple sectors. He noted that businesses may need to relocate if the situation is critical.
As for flooding in the city of Chiang Mai, Mr Thanapon said urban communities have limited knowledge about how to cope because they do not face the problem regularly.
He said the “Chiang Mai model” is not enough to deal with extremely high levels of floodwater.
That would require a multi-million-baht project, such as a large drainage tunnel beneath the city, to cope with flooding. However, stakeholders will have to determine whether such an investment is worth it.
On revising the city plan, he said its success relies on the cooperation of the public and those responsible for enforcing city planning laws.
He said people in Chiang Mai should realise that flooding can occur at any time, and given the amount of water, flooding is inevitable because there is no way to divert it elsewhere.
Key venues, such as hospitals, should explore methods to mitigate damage from flooding and consider the measures taken by the Shangri-La Hotel, which used a flood barrier to protect the premises.
“The public must understand that flooding is unavoidable, but its impact can be mitigated for key locations. Fortunately, this time the Bhumibol dam could still take water, which helped with drainage,” he said.
Reclaiming flood plains
Pianporn Deetes, campaign director for the Southeast Asia Programme at the International Rivers Network, said the flooding in Chiang Rai and Chiang Mai indicates water retention areas have been occupied by people amid uncontrolled expansion of cities.
Aerial photographs showed the rivers overflowed into the same areas that had flooded in the past, as if the rivers were reclaiming their former territory.
In the case of the Mae Sai River, she said the section near the 1st Friendship Bridge used to be much wider but structures on both the Thai and Myanmar sides have encroached on the riverbanks.
Upstream there are areas of exposed soil as the result of mining activities which may also contribute to the mudslides, she said.
“To reduce the severity of future flooding, it’s time we have a good understanding of extreme changes in climate. The earth is ‘boiling’ and we need nature-based solutions like preserving wetlands, rather than trying to control the river,” she said.
She agreed that international cooperation is needed to deal with transboundary flooding but said addressing the issue is a challenge for the government because the border areas involve several ethnic groups and participation from all sides is necessary.
Ms Pianporn also criticised authorities for their lack of preparedness in terms of warnings and responses.
She said those who suffer the most are the poor and the marginalised, and the government must find ways to help people rebuild their lives and livelihoods.
“I visited the Nam Kok community in Chiang Rai and saw the debris from small food shops. An electrician lost both his home and his tools while a community that grew vegetables was completely wiped out,” she said.