Bangkok: The sinking city faces severe climate challenges

Source(s): Urban Land Institute, the

By Ron Gluckman

Sceptics may question climate change, but in Bangkok, the impacts are already being felt—and are undeniable. Rainy season used to be as predictable as the bountiful rice crop, showering Thai fields like clockwork from mid-April into October, when the weather abruptly flips and it becomes bone-dry for six months. In recent years, though, rain has fallen unpredictably, causing flooding, damaging agriculture, destroying livelihoods, and threatening millions of people.

Meanwhile, temperatures are on the rise, and rapid urbanisation—combined with severe land subsidence—has put Bangkok on the watch list of the most vulnerable cities in Southeast Asia. However, events have focused attention, and some action, on the urgency of the problems. After a devastating flood early this decade, Bangkok launched numerous government-backed plans to address ecological issues and enlisted an array of international partners. Bangkok joined the 100 Resilient Cities project, which was established and funded by the Rockefeller Foundation and helps cities around the globe prepare for the myriad ecological and economic challenges of the 21st century.

“The government accepts that climate change is real,” says Supachai Tantikom, the chief resilience officer in Bangkok who was hired by the 100 Resilient Cities project as part of its standard agreement with cities in the project. In 2012, the government adopted a master plan that targets the reduction of carbon, traffic, and air pollution and the increasing of greenery.

The sinking city

Bangkok might seem a surprising addition to the climate change crisis list. Media coverage more often focuses on the impact of rising sea levels and surging tides on coastal residents, or on vulnerable low-lying islands. In Thailand, however, the effects of climate change are felt inland, along rivers and deltas, mainly in the crucial Chao Phraya River region. And Bangkok is particularly vulnerable, since this city of canals—called the Venice of Asia—is barely above sea level. Or it was. By some measures, it already has slipped below sea level; it is among the world’s fastest-sinking cities.

The capital of Thailand is sinking by up to two centimetres (0.8 in) each year, threatening this city of nearly 10 million. The Chao Phraya River has become prone to regular flooding, most critically in 2011, when heavy rains swelled waterways in the north, overflowing levies and swamping Bangkok for months. The 2011 flood caused over 800 deaths, cost an estimated US$50 billion, and affected 13 million people. The 2017 Global Climate Risk Index ranked Thailand among the top 10 countries in the world most affected by climate change.

The very survival of Bangkok is at stake as temperatures continue to rise each year, further contributing to rising water levels. The World Bank has predicted that 40 per cent of Bangkok could be inundated as early as 2030 due to extreme rainfall and changes in weather patterns.

One case study, from the 2017 Global Climate Risk Index by the nongovernmental organisation Germanwatch, looked at Bangkok, assuming a future temperature increase of four degrees Celsius. Under this scenario, the city would experience severe flooding, and around 40 per cent inundation by an extreme rainfall event and a 15-centimetre (6 in) sea-level rise (SLR) by 2030. Looking further, the study showed 70 per cent inundation and an 88-centimetre (35 in) SLR projected by 2080.

Concerns about flooding along the Chao Phraya River system are compounded by the surging seas expected with global warming. Thailand’s major water system irrigates much of the nation’s agriculture and provides sustenance to about half of the Thai population, including the urban sprawl from Bangkok through Samut Prakan, formerly a delta region prone to flooding and siltation for centuries.

The situation has always been unpredictable as evidenced by Wat Khun Samut Chin—sometimes called the Temple Sinking into the Sea. Once on land, the temple has been left on a tiny speck of an island, in a surging inland sea, thanks to erosion. On shore are the remains of forts that were moved repeatedly, as riverbanks fell away over the years. Greenpeace estimates that the waters of the Gulf of Thailand are rising four millimetres (0.2 in) a year, far above the global average.

Above and below: Chulalongkorn University Centennial Park in central Bangkok is conceived partly for public recreation and partly as a water-retention facility capable of holding up to 3.8 million litres (1 million gal) of rainwater runoff.
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Need for green and permeable surfaces

And then there is the severity of land subsidence in an urban landscape where concrete continues to spread and swallow up scant greenery. Bangkok has been called Asia’s least green city, with a scant 3.3 square metres (36 sq ft) of green space per person, according to the Siemens Green City Index. By comparison, Singapore offers 66 square metres (710 sq ft) and even New York City provides 23.1 square metres (249 sq ft), according to the report.

Paving over so much of the city has drastically reduced the permeable area, accelerating the sinking; Bangkok is reportedly sinking 10 times faster than sea level is rising. As the metropolitan area continues to sprawl and embrace a population exceeding 15 million, much of the city is now only half a metre (1.6 ft) above sea level, and many parts are already below it.

While it all sounds dire, one constant involved in planning for climate change in Bangkok is the need for better management of water flows, dams, and drainage. Everything flows around the Chao Phraya River. The Bangkok Metropolitan Authority (BMA) and national government have already committed to a matrix of responses that include raising levels of riverbanks, providing more drainage canals, and better coordinating the nationwide system of storage facilities and waterways. There also are proposals for more innovative measures, including digging new channels and building urban water storage systems.

Yet on the ground, those working hardest to meet the challenges of climate change concede that action has been slow. Climate change advocates noted that everyone remembers 2011, but there also is a tendency to think that those floods happened eight years ago­—and there has not been flooding like that since.

Waterflow management

Academics like Danny Marks say that history reveals a pattern of periodic flooding and droughts, “and Bangkok really isn’t doing much.” The Thai-American assistant professor of environmental studies at City University of Hong Kong has published numerous papers on the topic, and the ebbs and flows of the Chao Phraya River—by far the longest river in Thailand. Long ago dubbed “the Mother of All Rivers,” it has the prominence of the Nile, although it runs less than 400 kilometres (249 mi) from near Nakhon Sawan, where a trio of major upcountry rivers meet to form the Chao Phraya, which flows through Ayutthaya, down to Bangkok, and into the Gulf of Thailand.

More commonly called “the River of Kings,” it has been the lifeblood of the nation for centuries, connecting Ayutthaya—the ancient capital of Siam from the 14th century through the 18th century—to the newer capital of Bangkok. The latter was chosen after Ayutthaya was sacked because Bangkok was deemed easier to defend, with the Chao Phraya rerouted in an early waterworks project to create a new, more easily protected channel through the new capital.

So, as Marks points out, current concerns about dredging, storage, and diversions are nothing new. Thais have been managing the river system—for better or worse—for centuries.

The challenge now is to do much better, and soon; that became obvious after the floods of 2011. Officials have reason to be cautious about water releases from upcountry, where a lack of water during the dry season can devastate the vital rice fields, which rely on extensive irrigation. But with heavy rains in 2011, and dams kept full with the dry months in mind, there was nowhere to release water until it was too late. Bangkok and other areas downriver were flooded for months. Many industries fled to neighbouring countries and never returned. After the floods, more generous water releases were partially blamed for droughts.

The key, therefore, is to strike a balance between flood and drought. Over the next 35 years, the Royal Irrigation Department (RID) estimates that the area affected by floods will nearly triple, from 266,000 hectares (656,000 ac) to 660,000 hectares (1.63 million ac). Droughts will last longer, and major floods may occur as often as every seven years. Costs incurred by floods will skyrocket, the RID warned, from the present figure of about US$800 million per year, to US$5 billion annually.

“The projects we have in the pipeline are not just flood prevention measures, they also involve building facilities to store water for harvesting, which will help farmers during the dry season,” Deputy Prime Minister General Chatchai Sarikulya told the media during a recent trip to Chai Nat Province to address government plans.

Proposals include dredging and widening of drainage canals to the north of Bangkok, as well as construction of new waterways and storage facilities.

Other proposed projects include massive flood barriers, mainly around the capital, together with construction of what is effectively a new river—a 258-kilometre-long (160 mi), 160-metre-wide (525 ft) channel for US$6.5 billion—that would bypass Bangkok entirely. However, such schemes worry environmentalists and face heated opposition from local communities because of the enormous amount of relocations and land seizures that would be required.

“Monkey’s cheeks”

One smaller plan that has gained wide international attention is an innovative water storage park built by Thai landscape architect Kotchakorn Voraakhom. With her firm, Landprocess, she has specialised in the design of parks, gardens, and green roofs. In 2017, she unveiled Chulalongkorn University Centennial Park, a green oasis on 4.5 hectares (11 ac) of university land, with an amphitheatre and museum. More impressive is what is underneath: storage for collecting and cleaning water. The park has what is called Thailand’s largest green roof, covered with native grass and weeds. Besides providing more greenery and reducing the urban heat problem, the nearly 3.8 million litres (1 million gal) of storage could help with floods and drought.

Hailed for its innovation, the scheme is largely dismissed even by environmentalists as a well-meaning drop in the bucket. But the concept of water storage schemes—or, as Thais call them, “monkey’s cheeks”—is immensely popular.

This term was coined by King Bhumibol, Thailand’s beloved monarch, who reigned from 1946 until his death 70 years later. The king noted that monkeys hold food in their mouths until they need to eat. He reasoned that Bangkok needed to store water until the city could use it.

Urban planners and environmentalists like to talk about monkey’s cheeks, but they have not taken the next step: requiring them. “It would be good to have monkey’s cheeks for every new high-rise,” says Banasopit Mekvichai, one of the region’s top urban planners, a professor at Chulalongkorn University, and former deputy governor of the Bangkok Metropolitan Administration. She supports more parks, green space, and retaining ponds.

The reality, though, is that Bangkok has actually been moving in the other direction. Since 2014, when the military staged a coup, big infrastructure projects have become a means of boosting the stagnant economy. IconSiam, the largest shopping mall in Southeast Asia, with two super-tall residential towers, recently opened right on the Chao Phraya River. At about US$1.7 billion, it was the largest project in Thai history, eclipsing the Chao Phraya Estates, another development with two huge luxury hotels and another skyscraper, also on the river. But both are small compared with One Bangkok, a massive, integrated US$3.5 billion project comprising offices, retail, hotels, and residences on the old Night Bazaar site, smack in the middle of the city.

All these projects, critics say, eat up land that might have provided more greenery and natural water circulation. “We need more permeable surfaces, like parks,” notes Diane Archer, who grew up in Bangkok and is a research fellow at the local office of the Stockholm Environment Institute. “The problems are only getting more prolonged as we pave over the canals, ponds, and greenery with concrete.”

Urban heat island effect

Paving over canals, ponds, and greenery with concrete also intensifies heat island effects, another concern related to climate change, where an urban area is much warmer than surrounding rural areas due to human activities. The difference is usually more significant at night and can be attributed to concrete and other materials that retain and then radiate heat, and the lack of shade, greenery, and cooling water.

Bangkok became intensely focused on similar issues earlier this year, amidst a horrid bout of air pollution. The skies were choked with smog, residents clamoured for air masks, and planes seeded the clouds in hopes of triggering rain while guards at high-rises used garden hoses in hopes of washing away the toxic pollution. “It galvanised attention on some of the issues,” says Supachai Tantikom.

Pollution results from a variety of causes, including agricultural burning upcountry, but construction in the city kicks up storms of dust. In addition to all the real estate development, Bangkok is in the midst of a fivefold expansion of its outdated, 20-year-old subway system. “When that is done, we should be in better shape,” he says. He concedes, however, that Bangkok needs more than hope. “We really need to act on these plans.”

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