Sierra Leone and Hong Kong Flashcards
The mudflow in Sierra Leone happened in…
2017.
The saturated soil flowed down the…
Sugar Loaf mountain and hit the slum areas of Freetown.
Number of poeple died in Sierra Leone was…
1100.
Sierra Leone is LLIC…
(Leas-low…), so it has poor development, due to historical factors and poor neighbours.
Deforestation on Sugar Loaf mountain decreased…
the interception, so more surface runoff.
Slump development on…
the slopes increased the shear stress. No drainage on the slope=more surface runoff and throughflow.
Residents ignored the rule…
not to build on the Sugar Loaf mountain(2014) and it is a national park.
Natural causes of mudflow:
- intense rainfall
- steep topography
The vulnerability of Freetown is…
exacerbated by: diseases, poor sanitation, lack of aid.
Hong Kong has a long history of…
landslides, due to intense precipitation, steep topography and dense human development
The risk of the Domino effect is due to…
gentrification on the slopes, causing building smashing to the next and so on.
In Hong Kong in…
1996, rainstorms triggered landslides and 64 people were killed and 2500 made homeless.
In June 1996 over…
700 landslides were recorded.
(Hong Kong) Vegetation may increase…
the problem as the trees held back many small landslides and allowed larger washouts to occur
Hong Kong consists of…
islands, with natural steep topography >30 degrees.
(Hong Kong) Geology:
-made of sedimentary rocks such as granite-prone to failure and weathering
(Hong Kong) Slope Safety System was…
set up, with over 700 employees, investigating and researching the causes of landslides.
(Hong Kong) Private owners of…
buildings on slopes had to take responsibility and maintain the slope. Neglect could lead to imprisonment.
(Hong Kong) Due to measures taken after 1996, the risk was reduced by…
50%.
(Hong Kong) Surface drains are vulnerable to…
blockage, increasing the risk of landslide even more. Confusion over responsibility=many not maintained.
(Hong Kong) Man-made slopes were…
the main methods of stabilisation. Slopes were protected from infiltration and erosive effect by impermeable covers.
(Hong Kong) Greening techniques were used to…
increase the interception.
Types of Greening techniques:
- Mulching system
- Long-rooting grass
- Fibre reinforced soil system
The mulching system involves…
protective cover which makes possible for vegetation to grow and secure the place.
The long-root grass is fast…
growing and cost-effective(low maintenance).
Fibre reinforced soil system involves…
mixing polyester fibre into sandy soils. This resists the tension created by the component of the wight down the slope.
