3.4 The human impact Flashcards
1
Q
Example of human actions leading to a landslide
A
- Abbotsford landslide, Dunedin New Zealand
2
Q
What human activities caused the landslide
A
- There were cracks in their driveway, brickwork and floors
- A leaking water pipe had been pulled apart
- Deforestation
3
Q
Explain how these human actions caused the landslide
A
- Water pipe: this water made the layers of clay on the hill soft and the sandstone above it was sliding on this slippery surface
- Deforestation: reduced the evapotranspiration in the area and there was less binding of the soil by plant roots
- Urbanisation: in previous 40 years, they had modified the slopes by cutting and infilling and altered the surface drainage (speeding up the removal of surface water)
- Quarrying of material at the toe of the slope removed support from the base
4
Q
Explain pinning
A
- The attachment of wire nets or concrete blocks to a rock face or slope so that the risk of rock falls + erosion is reduced
5
Q
Explain netting
A
- A net is placed over the slope to collect fragments of scree which can safely be removed at a later date
- Used in areas of tourism
6
Q
A
7
Q
Grading explain
A
- Refers to the re-profiling of slopes so that they become more stable
8
Q
Explain aforestation
A
- The planting of new forest in parts of a slope to increase interception and reduce overland flow
- May take some years to be effective as young trees intercept small amounts of water
9
Q
Drainage explain
A
- Drainage can be inserted into the slope to remove water
- Prevents water build up which leads to landslides
10
Q
Other methods to reduce chances of landslide
A
- Reinforce rock walls with cement or anchor bolts
- Sealing surfaces cracks to prevent water infiltrating through
- Flattening the slope
- Walls at the foot of the slope
11
Q
Between 1960 and 1970, how many landslides were natural and how many were human related
A
- 200 natural vs around 400 human related
12
Q
What does Hong Kong do (GEO - Geotechnical Engineering Office) + GOVERNMENT
A
- Investigates and researches the causes of significant and serious landslides ot improve the SLOPE SAFETY SYSTEMS
- ONE OF HONG KONG’S GOVERNMENT INTERVENTIONS IS TO ENSURE THE PRIVATE OWNERS OF SLOPES TAKE RESPONSIBILITY FOR SLOPE SAFETY
- If a slope owner does not comply with the regulation, prosecution will be HK$50,000 fine and even IMPRISONMENT FOR UP TO A YEAR
13
Q
Has this been a success?
A
- YES - SINCE 1977 THE RISK OF LANDSLIDES HAS REDUCED BY 50%
14
Q
What are greening techniques
A
- Refer to the use of natural vegetation to reduce the risk of mass movements
15
Q
Greening techniques: explain mulching
A
- Refers to the use of a protective cover on the slope
- This allows plants to grow securely through it providing more strength to the slope and secures the protective sheet in place
