Manila is reeling after a super typhoon. We must prepare fast-growing megacities for worsening disasters

Super Typhoon Gaemi was strong enough to sink an oil tanker. Philippine Coast Guard/AP^[9]

Hiding in plain sight

The Philippines has the highest disaster risk^[10] of any country. The Pacific archipelago nation stretches 1,850km north to south and lies directly in the path of many typhoons. The nation is also on the Ring of Fire^[11], putting it at risk from earthquakes and volcanic eruptions.

But disaster risk isn’t just about how many disasters strike. It’s also about how vulnerable a country is, on both social and infrastructure fronts. Recent research has found^[12] the capital of the Philippines, Manila, is particularly vulnerable.

Manila is one of the densest cities in the world, housing more than 42,000 people per square kilometre. An estimated 15 million people now live^[13] in the metropolitan Manila region – ten times the population in 1950. Several large rivers and about 30 tributaries^[14] run through the city.

As the city has grown, concrete surfaces have multiplied and green space has shrunk. Gutters, stormwater drains and flood management infrastructure have not kept pace.

The scale of flooding this week has brought back memories of Typhoon Ketsana (known as Ondoy in the Philippines) which hit Manila in 2009. Some areas went under three metres of floodwater.

Super Typhoon Gaemi has had a similar impact. Roads became impassable. Rivers broke their banks. Residents of informal settlements – often built near rivers – had to flee. The city’s drains could not cope^[15].

Low-income families often build houses in flood-prone areas near rivers. Wirestock Creators/Shutterstock^[16]

Intense rainfall in the catchments forced dam managers to open floodgates^[17], compounding flooding from urban rainfall.

Floodwaters carry debris and waste through cities and homes. When they recede, they leave behind a higher risk of disease^[18].

Flood damage is projected to worsen^[19] by the end of the decade, as urbanisation continues without enough infrastructure investment.

The Philippines government claims poor waste management contributed to the flooding, saying dumped garbage blocked waterways and clogged drainage systems^[20].

Certainly, poor waste management can make flooding worse^[21]. But we cannot simply say the scale of this disaster is due to waste management issues, just as we can’t say climate change was solely to blame. Sprawling, wide-reaching disasters like this have many causes.

What would it take to cut disaster risk?

As climate change loads the dice for more and worse disasters, leaders in the Philippines will have to tackle their nation’s systemic vulnerabilities to disaster, as will other frontline nations.

We’re starting to see evidence climate-boosted disasters hit people in emerging urban centres harder. Typhoons are at their most lethal^[22] when they strike fast-growing megacities in emerging economies.

In 2007, the world passed an urbanisation milestone^[23]. For the first time in recorded human history, more people lived in cities than in rural areas. Since then, urbanisation has only accelerated, as people from rural areas head to burgeoning megacities such as Lagos in Nigeria and Dhaka in Bangladesh. But residents of these cities are often more at risk from flooding and other climate-boosted extreme weather events.

What can we do? As Filipinos braced for Typhoon Gaemi, many frantically looked for information. Data on dangerous flood areas from open access hazard assessment tools^[24] proved useful to boost individual preparedness.

But governments must actually plan for and tackle root causes of flooding to make fast-growing cities better able to resist the disasters of the future.

University of Sydney Masters students Sheryn See and Isaac Besarra contributed to this article.

Read more https://theconversation.com/manila-is-reeling-after-a-super-typhoon-we-must-prepare-fast-growing-megacities-for-worsening-disasters-235598

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