Rainy weeks have sparked fears that Bangkok will be submerged, prompting authorities to implement flood measures ranging from unclogging the dilapidated drainage system to monitoring water levels around the clock.
However, the capital needs urban planning to keep land for water absorption to prevent flooding, worsened by global warming.
"Urban flooding is caused by higher rainfall, which now exceeds the drainage capacity of 60mm per hour," said Asst Prof Wijitbusaba Marome, the director of the Urban Futures and Policy Research Unit at Thammasat University.
Bangkok and several big cities in Thailand are so fragile when it comes to flooding. Only an hour of rain, for example, can cause flooding that subsequently leads to many other problems such as traffic congestion, accidents and so forth. Urban planning is therefore crucial as a flood prevention protocol, a factor that could bring about a sustainable city.
Wijitbusaba said the city's sewerage system fails to deal with the volume of water because it is an old combined system that carries used water and rain. When population density increases, it overloads the drainage facility. "Urban construction leads to loss of land for collecting water," she said.
Asst Prof Wijitbusaba Marome, director of the Urban Futures and Policy Research Unit at Thammasat University. Asst Prof Wijitbusaba Marome
Flooding is further compounded by the impact of climate change. She said Bangkok and its adjacent provinces are less than 1m above sea level, but some areas are now sinking.
"When pipes are not at the same level, they have difficulty draining sewage," she said.
The Bangkok Metropolitan Administration (BMA) is using the pipe jacking technique to increase water storage area, constructing tunnels for releasing water, and expanding river dykes to prevent flooding. It is also working with the Royal Irrigation Department to regulate the amount of upstream water.
Wijitbusaba said, however, structural measures are not flexible because they are designed to address specific issues. In fact, current flooding results from a combination of rain, runoff and tidal bore. Non-structural measures should be implemented, especially urban planning.
She cited the Netherlands as an example of positive land management.
"The country uses riverside areas for collecting water. If water exceeds the level of dams, it will overflow communities, but using empty land is more flexible."
Wijitbusaba said authorities should integrate urban planning that involves zoning and regulating density into management. Urban expansion into low-lying areas, like Bangkok, increases the risk of flooding and takes away land that can be used for water collection. The rate of urbanisation now surpasses the amount of rain.
"If we can manage this, it will help reduce the risk of damage," she said.
According to the principle of urban planning, residents should use available services, like drainage and public transport, for cost-effectiveness. Wijitbusaba is working on the Global Futures Cities Programme with the BMA and the UK. It seeks to curb urban sprawl by developing residential areas around public transportation systems.
"Mostly, developers focus on building high-rises, but there are social and environmental aspects. Besides flooding, local people should not be displaced because real estate prices are going up," she said.
Wijitbusaba said cities must be resilient or adaptable to change. When it comes to water, resilient cities consider it in terms of demand and supply. For example, they find ways to cope with heavy rain by storing it for future use.
"On the other hand, we release flood into the sea and borrow water from the agricultural sector for urban consumption. That is why city dwellers never feel the impact of drought," she said.
When asked how to create resilience, she said the government should take a comprehensive approach to water management -- flood, drought and tidal bore -- and invest in basic infrastructure without creating new risks, including urban expansion over waterways.
Meanwhile, citizens should form networks and educate themselves because increasing public awareness will put pressure on the public and private sectors.
"Real estate developers are starting to think about resilience because they can face lawsuits [over flooding]. When customers resell houses in flood-prone areas, it can taint their company image," she said.
Greenpeace Southeast Asia released a report in June. Seven cities in Asia could be impacted by sea-level rise and coastal flooding by 2030. Bangkok's vulnerability to inundation is caused by monsoon, soft soil, urbanisation and land subsidence. If a flood occurs in 2030, over 96% of Bangkok's land is at risk of submersion.
Former Bangkok governor Bhichit Rattakul, who is now the president of the Thai Network for Disaster Resilience, dismissed the possibility of moving the capital city. However, he suggested that the Chao Phraya delta should be developed to prepare for heavy floods.
"The Royal Irrigation Department should improve 12 lowland areas [the lower Chao Phraya River basin] that can hold 1.5 billion cubic metres of water and set up new communities there," he said.
Building Sustainable Cities is a 13-part series that explores essential elements & insights on how individuals and businesses can take action to forge a cleaner, greener tomorrow in collaboration with UOB Thailand. You can view the whole series here.
