Hong Kong is a very wet country due to tropical storms that bring heavy rainfall. This, coupled with Hong Kong's rapid urban development on hilly terrains, has led to widespread occurrences of devastating landslides.
The rainfall is very high but seasonal, averaging 2000 mm (78.7 in) in the wet season from May to October. The precipitation occurs in heavy downpours that last several days. As a result, the rainfall fully saturates the soil several times throughout the season, and when the soil is fully saturated, the strength is significantly lower. This increases the chance for a mass movement.
Focusing on 1972 in Hong Kong, they faced a series of landslides, the worst in Hong Kong's history. This year, Hong Kong faced two deadly landslides that occurred on the same day, claiming 138 lives. The landslides in Hong Kong are rarely slow; they occur almost instantaneously, making them very dangerous. This tragedy, however, led Hong Kong to be more proactive at mitigating landslides, their most dangerous threat.
After the 1970s, Hong Kong's government set up the Landslip Preventative Measures (LPM) program to deal with slopes that could result in landslides. The program essentially observes slopes that could be potential threats, and they gain more info on an identified slope by continually following it. If needed, LPM designs and constructs an upgraded incline that lessens the chance of a landslide. This system works very effectively for Hong Kong as future landslides were less common and had fewer deaths.
An image of one of the twin landslides from 1972
Sources:
http://www.geog.com.cn/EN/10.11821/xb1997S1013
https://qjegh.lyellcollection.org/content/8/1/31
https://storymaps.arcgis.com/stories/c3d76d90cd474bf58b4a4c1464aa1dbe
Interesting post Tyson, India's recent rainfall average is 876.8mm which is far less than Hong Kong yet India seems to suffer from landslides at a higher rate. I wish India could implement a system such as, "the Landslip Preventative Measures (LPM) program to deal with slopes that could result in landslides".
ReplyDeleteVery interesting reflection! This reminded me of an article I read (below) about how most global non-seismically triggered landslides were located mostly in India/China/etc..I guess the heavy rains/monzoon season impacts these countries very seriously!
ReplyDeleteThat image you posted is amazing. It gives us a good visual of the big scale of these events!
https://nhess.copernicus.org/articles/18/2161/2018/
I find it interesting that this country contains tropical weather, this is one of those countries that has a different type of humidity and rain levels compared to the U.S. Which I realize that there country looks cold and rainy most of the time but in reality it is very hot a humid at the times it looks cold.
ReplyDeleteHi Tyson, I really enjoyed your post about landslides in Hong Kong. That's amazing how much rainy months and tropical storms that hit that region which from the picture it affected many people in that area. It happens so quickly and hopefully in the future people are aware of the slopes which have been affected or could still be a potential hazard have some safety regulations in mind. This is exactly how my country that I have has endured heavy rains and earthquakes which lead to landslides or flooding because people have to find a clean source of water when they start developing in the area.
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