Fears of flooding have returned again with news the Royal Irrigation Department (RID) will discharge more water from the Chao Phraya dam in Chai Nat to accommodate run-off from the North.
Indeed, "the Great Bangkok Flood of 2022" was among trending topics on social media which went into a frenzy on July 20 as up to 150mm of rain fell in parts of the capital between 7pm-1am.
For some long-term residents, videos of pedestrians caught off-guard in knee-high water and stalled motorcycles may recall the devastating 2011 floods.
Residents of Bangkok are well-accustomed to monsoon rains and annual flooding, especially after Wan Khao Phansa, or Buddhist Lent. Over the decades, the Bangkok Metropolitan Administration (BMA) has invested massively in water drainage infrastructure. During 2011-2021, City Hall spent 50 billion baht on flood drainage.
The Department of Draining and Sewerage received the largest share of the BMA's annual budget: around 7 billion baht, or 10% of City Hall's budget to build and take care of water tunnels, dykes, pumps, and increased storage capacity to control releases and divert excess water to the Chao Phraya River, and eventually the sea.
But each year, the system seems to fail. Why? Part of the problem stems from unpredictable weather patterns which are likely to intensify in the future. As the Intergovernmental Panel on Climate Change (IPCC) points out, increases in monsoon precipitation in Asia, including Thailand, are "very likely" due to climate change.
But is unpredictable weather the sole cause of this yearly ritual? On July 20, the morning after the latest floods, city officials had to remove over 300kg of garbage, from plastic bags to household items such as mattresses and chairs, from 14 major flood drainage canals such as the Rama IX canal.
Without the garbage, the drainage capacity of these canals is 60mm per hour, well below the 120-150mm of rain dumped earlier this month. But in reality, their actual capacity is likely far less.
This problem is further compounded by city authorities' lack of ability to maintain or upgrade existing infrastructure. Drainage pipes are still at their original 50cm to 80cm width despite discussions over the years to increase their diameter.
After the latest round of floods, Bangkok governor Chadchart Sittipunt pleaded with residents near canals to keep their rubbish at home until municipal services could reach them. During a time of peril, such requests are likely heeded, but old habits die hard.
The BMA must encourage communities near canals not to litter. However, BMA has not done enough to solve the garbage issue.
Even worse, City Hall has again delayed hiking the collection fee, the third time since the Covid-19 pandemic. Without financial resources for waste management, needless to say residents' habits will never change.
Diversifying flood-prevention solutions away from controlling water flow and diversion is vital. One option is nature-based solutions such as urban watersheds.
The wetlands at Benjakitti Park, for example, will increase green coverage and also serve as an embankment and flood absorber to ease pressure on strained drainage systems.
Besides the loss of life, the 2011 floods cost the economy 1.43 trillion baht. With the country still recovering from the economic downturn caused by Covid-19, it needs a new strategy to prevent another catastrophe.
