Thai battle against global warming hits the roof
WHEN Bangkok’s oldest university called for ideas for a symbol to mark its centenary year, landscape architect Kotchakorn Voraakhom successfully pitched a design for a park.
It was intended not only as a welcome green space in the middle of the congested Thai city of 10 million people, but as a place that could also retain large amounts of water, reducing monsoon flooding around Chulalongkorn University.
Parks and “green roofs” planted with vegetation soak up rain during the annual monsoon and help dense urban centres like Bangkok adapt to climate change, Kotchakorn said.
“We need to be thinking about everything we build in the context of mitigating climate-change impact It can’t be just about aesthetics, but also about serving a purpose. This was Bangkok’s first park in many years, so we had to make it count.”.
The city, built on the floodplains of the Chao Phraya River, is expected to be one of the urban areas hit hardest by warming temperatures.
Once a network of canals that earned it the moniker “Venice of the East”, Bangkok has filled in many of those water channels for construction, and is sinking by more than 1cm each year, according to climate experts.
Flooding in many parts of the city is common during the annual monsoon. The rains in 2011 brought the worst floods in decades, putting a fifth of the city under water.
“With so much construction and fewer canals, there is nowhere for the water to go,” said Kotchakorn, who heads Bangkok-based landscape architecture firm Landprocess.
“But instead of building embankments along the river or thinking of ways to get rid of the water, we should be thinking about how to live with the water, how to manage the water.”
A plan to build a promenade along the river will worsen floods in Bangkok, environmentalists warn.
The Thai capital also has one of the lowest ratios of green space: 3.3m² a person compared with New York City’s 23.1m² and Singapore’s 66m², according to the Siemens Green City Index.
A “metro forest” project in a Bangkok suburb has converted 0.8 hectares of abandoned land into a local forest with native trees to make a start on reversing urban sprawl.
The city’s 4.5ha Chulalongkorn Centenary Park designed by Kotchakorn is inclined at a 3º angle, so that rain and flood water flow to its lowest point into a retention pond.
At the park’s highest end, a museum is topped by a green roof covered with native plants, which filter rainwater before it is stored in large tanks underground.
Rainwater also flows through the park’s lawn and wetlands where native vegetation filters the water, while its walkways are made of porous concrete.
The park holds huge amounts of water that can be discharged later or used in the dry season, much like a monkey holds food in its cheeks until it needs to eat, said Kotchakorn, echoing the idea of Thailand’s revered late King Bhumibol Adulyadej to contain flooding in the capital city.
“No water that falls into the park is wasted,” said Kotchakorn, who is also creating a 15ha park and green roof for Bangkok’s Thammasat University.
While infrastructure upgrades are an essential part of tackling urban flood risk, “softer” measures are also crucial, said Diane Archer, a Stockholm Environment Institute researcher in Bangkok. A key part is working with locals so that they can learn to take action themselves.
“This includes highlighting the important role that green roofs and permeability of driveways and yards can play in reducing surface (water) run-off, with added benefits in reducing urban heat island effects,” she said.