Two years ago, extreme rainfall inundated Hong Kong, turning roads into raging rapids, submerging car
s and flooding malls, making it one of the city’s most costly weather events ever. When another round of record-breaking r
ains drenched the city last month, the damage and disruption were comparatively minimal.
“I was looking outside the window, seeing the rain coming down, and I was expecting way more impact than I s
aw afterward,” said Andreas Prein, a weather expert who was in town for a forum on extreme rainfall the same week
of the deluge. Other overseas attendees also remarked on how quickly Hong Kong returned to business-as-normal: the
y gathered for drinks downtown within a couple hours of the rains subsiding.
The severe storm notched the highest-ever August daily rainfall total, but it was also up against the city’s sharpened flood management strategy: In t
he past two years, Hong Kong has more than doubled its annual spe
nding on stormwater drainage to an estimated HK$3.17 billion ($407 million) to address the evolving threat from extreme rains turbocharged by a warming climate.
Other regions have also spent handsomely in their quest to tame stormwaters. Tokyo boasts a world-class flo
od defense system, Singapore has splashed out on drainage infrastructure, and the Netherlands continues to rely on its network of barriers, dams and wind-powered pumps. But
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globally, work on climate-proofing has slowed and the gap between required and needed adaptation finance is at least $187 billion a year, according to the United Nations.
For now, billions in investments in sprawling infrastructure in Hong Kong have kept the full wrath of natur
al disasters in check. That vital but little-known work began decades earlier, long before climate risks entered the public consciousness. Much of Hong Kong is densely packed and perched on, or built at the foot
f, steep slopes. The city averages 2,400 millimeters (94.5 inches) of precipitation annually — nearly double what New York City gets — and tropical rain is notoriously hard to predict. As a coastal city, storm sur
ges and rising sea levels put additional stress on its drains.
This combination of factors “is quite unique to Hong Kong,” said Huan-Feng Duan, professor of hydraulics an
d water resources at the Hong Kong Polytechnic University. “The very fast flooding issue means it requires a very high standard of research and also engineering.”
Now, ever-higher temperatures are risking more intense rains, requiring more improvements to Hong Kong’s extreme-weather response.
Driving that effort is the Drainage Services Department, which oversees some 2,800 kilometers (1,70
0 miles)of stormwater drains — more than the length of the city’s public roads. In the nearly four decades since its establishment, the DSD has invested over HK$32 billi
on in drainage works to reduce flooding impact. That’s no longer enough.