HK mass movement Flashcards
Causes
60% of land in HK is mountainous
most landslides occur during or after rainstorms
tropical climate increases rate of chemical weathering, which decreases shear strength of slopes
granite and volcanic rocks on higher ground are prone to failure and are seriously weathered
previously very dense population with lack of management meant shanty towns built on slopes increased chance of mass movement
1972 landslides
138 deaths
management response
1977 introduced territorial landslide early warning system
needs to be constantly improved as prospect of increasingly intense rainfall due to climate change
geotechnical engineering office
updating, maintaining slopes
landslide potential index indicates areas that are most at risk
however only 10% of people asked had heard of landslide potential index
if slope does not comply with regulation, fine and imprisonment
HK observatory determines incoming rainfall to cross check with previous mass movements and determine if warning is required
landslide potential index estimates risk of landslides after rainfall
GPS sensors on slopes to detect movement
monitoring of landslide barriers
retaining walls in place to keep slopes in place
new warning system which gives forecast 6 hrs ahead compared to 3 hrs
slopes have signs indicating risk of landslides
maintenance of slopes
mulching system - high water retaining capacity
resistance to rain erosion
ability to hold position in steep slopes
long rooted grass - natural
cheap
fast and easy
can be applied on steep slopes
fibre reinforced soil system - low maintenance
fibre strengthens soil
visual improvement
restoration of habitats
challenges
Hong Kong is compact and has money available to invest in technology needed.
However, countries like Sierra Leone do not have the capabilities. 2017, landslide killed 1000+. Authorities have little data to provide to their citizens about the likelihood of a disaster.
