Flood victims swept away in “a year’s worth of rainfall”

Taiwan has been hit hard by Typhoon Morakot. Fourteen are dead, 51 officially missing, and hundreds more unaccounted for. Bridges and even damns have been swept away by "unseen" amounts of rainfall, displacing over a million people. A meteorologist visiting the country filmed the following footage on his digital camera.

Typhoon Morakot swept into Taiwan on Friday after leaving over 20 people dead in the Philippines. The result of 2.5m rainfall and wind speeds of 85 mph, the typhoon toppled a six storey hotel, left cars submerged under water and sparked huge landslides, leaving the whereabouts of one entire village unknown. It moved on to China's east coast on Sunday afternoon, where over a million people have been evacuated in face of 120 mph gales.

“The most rainfall I've ever seen and will probably ever see in my life”

Nick Engerer, 23, is a graduate meteorologist from Ohio, US. He was travelling with a fellow storm chaser when the storm hit Taiwan. The following videos were filmed by him and uploaded to YouTube.

As a meteorologist this is the most rainfall I've ever seen and will probably ever see in my life. Over two metres of rainfall in a few days - that's almost as much as Taiwan normally has in a year! In a thunderstorm you see around 3 - 4 inches (7.5 - 10 cm), which we consider a lot. In a hurricane it's around 20 - 30 inches (50 - 75 cm), which is loads. So 8 - 9 feet (around 1 metre) is, as far as I know, something so far unseen.

If this had happened in Europe or the US the damage would have been far greater. Taiwan is experienced in both heavy rainfall and strong earthquakes. It's an island with steep mountains, meaning that once a typhoon arrives there, it can keep raining by feeding from the warm waters surrounding the island and therefore stay powerful for some time. When the typhoon moved on to China it was not as hard-hitting because the circulation of water was weakened.

The infrastructure is superb here. The sewers are good, the bridges are strong. Because typhoons have been handled well in the past, people aren't scared when a typhoon is on its way. It's very unusual for people to die and everyone here is really shocked that so many lives have been lost.

This bridge, east of Chiayi City in the Alishan mountains (in central-eastern Taiwan), was swept away on Saturday night. Once a bridge is washed away there are whole towns/ cities with no access to the mainland. Those cities are gradually being evacuated by zip wires and it's probably going to take one or two years to replace all the bridges.

There's a 400-metre span missing from this bridge southwest of Kaohsiung City (southwest Taiwan). This event unfortunately claimed the lives of several people as the bridge collapsed in sections, leaving one car stranded on a part which was then washed away. The reason they're so fast to rebuild the road (at the end of the clip) is because it leads to a big industrial area including a petroleum refinery.

It blew my mind when I saw this damn in the Bajhang River washed away. The amount of water that it takes to wash away such an enormous chunk of concrete is unthinkable. Plus, when a damn gives way it puts a lot of pressure on the next one, so there's little doubt what happened downstream. What's sure is that Taiwan was hit really badly, and we're only just now beginning to hear about all the death and tragedy."

Comments

That's really tragic. I've

Submitted by Unregistered user on Thu, 13/08/2009 - 09:29.

That's really tragic. I've seen such flooding also in the Philippines when Mt Pinatubo was actually raging when it erupted in 1991. And it's really scary. Houses where swallowed by the raging waters and the residents can't do anything than to cry and hope that no one in their family were taken by the flood.

Unregistered user

Worse in Europe?

Submitted by Lo (not verified) on Tue, 11/08/2009 - 15:10.

Interesting (and worrying) when you say that the US or Europe would have been even harder hit by a storm of that magnitude. How is Taiwan's infrastructure better prepared than that of the western world?

Unregistered user

Infastructure

Submitted by Nick Engerer on Fri, 14/08/2009 - 12:51.

Hi and thanks for your comment.

I made the statement that the infastructure of Taiwan is better suited for an event such as this for two reasons.

The first: Taiwan was is located along any active plate tectonics region and was formed long ago by volcanoes. It is also very tropical. When large mountains such as the one of Taiwan (up to 13k ft!) exist in such a tropical region surrounded by warm ocean water, the place is bound to get a lot of precipitation. When air is forced to move over mountains, it is lifted and it cools (because the air pressure drops it must cool, recall your Chem classes PV = nRT !). As it cools, it reaches the dewpoint and the air condenses and you get I(orographic) rain... in this case you get A　LOT of it because the air is so saturated through such a thick layer. For this reason, Taiwan over thousands of years had become incredibly efficient at draining water. The water levels here returned to normanl very quickly after the Typhoon moved out of the region (levels were falling before the event even ended!). Such is not the case anywhere in Europe or the US, where the topography has not been so well conditioned to large amounts of rainfall; so such a rainfall event would have more of an impact.

The second reason: The people of Taiwan have been subject to intense Typhoon storms for many many years... these people have know well before bridges were built and roads were laid that they needed to be prepared to Typhoons and lots of rain. For this reason, the islands infastructure has been built to withstand much more water than could ever be expected. Even after 3 meters of rain in 72 hours in some locations(and that is an ABSURD amount of rainfall, more rain than Taiwan usually gets in a year), the man made reservoirs in the mountains had plenty of additional volume, and only 12-15 bridges were washed out, with a handful of dams failing. If you were to ask any civil engineer or hydrologist in Europe or the US what that amount of rainfall would to over an area of the same square mileage as Taiwan, the reply would be something along the lines of "massive devastation to property and debilitating destruction to infastructure".

I hope this answers your comment completely. Thanks for reading the article!

Nick Engerer
engerer@ou.edu
NDSEG Fellow
Univ. Oklahoma
(330) 283-6841
Homepage

Nick Engerer

United States
Meteorologist

Errors

Submitted by Nick Engerer on Fri, 14/08/2009 - 13:35.

Sorry for the grammatical errors...using a mandaring keyboard/computer set up and it is hard to type/edit things here.

Thanks

Nick Engerer
engerer@ou.edu
NDSEG Fellow
Univ. Oklahoma
(330) 283-6841
Homepage

Nick Engerer

United States
Meteorologist

Just think about Hurricane

Submitted by Lily (not verified) on Tue, 11/08/2009 - 15:45.

Just think about Hurricane Katrina. That was just a class 3 Hurricane, and it was so "devastating." Largely because the infrastructure was inappropriate. Taiwan gets hit by multiple class 4 and class 5 hurricanes every year. That means almost all houses and buildings have their own mini water reserve, in case storm drains overflow into clean water reservoirs, as can happen every 3-4 years. Buildings are made mostly out of concrete, and major rivers (like the one in Taipei) are encased in enormous expansive contingency riverbeds and walls, where one wonders "is that really necessary?" And then something like this hits, and one thinks, "ah....that's why." In general, in the western world, the threat from hurriccanes is not dire enough to prompt communities to demand such infrastructure.

Unregistered user