Going with the flow

Going with the flow

Engineers say flood-prone Bangkok should learn to live with water rather than trying to keep it out, write Pratch Rujivanarom and Supoj Wancharoen

The capital of Thailand is always faced with water problems. The historic flood in 2011 that submerged 65 provinces across the country, including several districts of Bangkok, was just an extreme example.

Almost every year after heavy rainfall, Bangkok roads are inundated with floodwater.

This is one of the major annoyances that urban citizens have to endure, as flash floods on Bangkok's streets are accompanied by serious traffic congestion and travel difficulties.

Past governments and Bangkok governors have tried in vain to solve Bangkok's chronic flood problem. Now we have the threat of rising sea levels caused by climate change to worry about as well.

So, water management and city planning experts have come up with suggestions to radically reform the city's drainage system and city planning as they once again set to work on how to solve the city's flooding problems.

poor drainage system

"The first and foremost problem that causes constant flash floods in the capital is the poor state of the city's drainage and flood prevention system," said Chawalit Chantararat, board member of TEAM Group Plc and chairman of the Consulting Engineers Association of Thailand.

He said that as Bangkok continues to face chronic flooding from heavy downpours, riverine floods, and surges in seawater levels, the city's drainage and flood prevention system is unable to properly drain rainwater or prevent rising rivers from overflowing to the city.

"Even though a series of floodwalls have been constructed along the Chao Phraya River in Bangkok, some areas are still not protected by floodwalls and remain weak spots in our flood prevention system. Some of these floodwalls are also in a state of disrepair and have a water leakage problem," Mr Chawalit said.

"Since Bangkok is facing more floods from rivers overflowing due to rising sea levels, Bangkok's riverine floodwalls need to be strengthened and extended to cover all riverside flood-prone areas. More water gates are also needed at the mouths of canals to prevent floodwater from pushing deep into the city."

Bangkok's drainage system also requires urgent improvement, as the city's drains are often clogged with garbage and sediment, or have subsided and broken, due to a lack of proper maintenance, which hindered water drainage capacity.

This is why Bangkok often floods even after a few hours of rain.

"We also need to dredge Bangkok's many canals to allow water to drain more efficiently, as well as construct more water retention areas such as monkey-cheek ponds and underground water banks to hold floodwater and keep the city dry," he said.

"It is more important than ever for Bangkok to step up flood preparedness since we are going to see more and more flood events as climate change intensifies."

City plan should be revised

However, not every expert agrees that constructing hard flood prevention structures can solve Bangkok's water problem.

Decha Boonkham, a National Artist of Thailand in the field of landscape architecture, said that instead of defying floods, we should revise the city plan to live with water.

"When looking at the lower Chao Phraya River Basin from a satellite image, we can see that Bangkok and its vicinity sit in a low-lying flood plain that naturally floods every year, which means we are living around water," Mr Decha said.

"Considering the way Bangkok people lived in the past, in a kind of oriental Venice, we can see clearly that locals in this region lived in harmony with water up until the modern era, when we started to live as urban dwellers, whose lives are cut off from water."

He said that as Bangkok grew, the city expanded into natural floodways to the east and west, causing seasonal floods to be longer and more intense, as the city blocked the waterways.

"Back in 1960, Bangkok drafted its first modern city plan. This first plan clearly acknowledged the seasonal flood nature of this area and designated zones for floodways to the east and west of the city," he said.

"However, this city plan has never actually been used, as the city grew rapidly in the following decades without any planning."

He said the sustainable solution for Bangkok to solve its water problem is to revise the city plan and make way for water to coexist with the city.

This can be done in many ways such as limiting the expansion of the city to flood-prone areas and reconsider future urban development plans to ensure they are suitable.

Weeraphan Shinawatra, a city planner for the Society for the Conservation of National Treasure and Environment (SCONTE), agreed the real problem that intensifies flooding in Bangkok is poor city planning, as uncontrolled urban expansion eats away at floodways, causing massive floods such as those of 2011.

Authorities are planning to build the third outermost ring road around Bangkok. He said it should comprise north–south floodways along with a new ring road to serve as water highways to drain floodwater during flood season out to the sea.

Apart from unplanned urbanisation, Mr Weeraphan said hard flood prevention structures such as concrete floodwalls, water gates, and river embankments are also part of the problem, as they further separate people from water and defy nature.

Floodwalls are a dangerous way to prevent flood, he said, pointing out that if the floodwater in the river is high enough, water can seep underground and destabilise the structure, causing the floodwall to collapse and generating severe flash floods, similar to flooding of New Orleans during Hurricane Katrina in 2005.

Furthermore, he said these floodwalls also block water from draining into the river, causing floods behind floodwalls, as many riverside communities experienced after their tall concrete embankments were constructed.

"We need to rethink the ways we deal with flood. We cannot defy nature, but we can cope and live with it, just like our ancestors did," he said.

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