Podcast
Questions and Answers
What was the primary cause of the June 1966 landslides on Hong Kong Island?
What was the primary cause of the June 1966 landslides on Hong Kong Island?
Which type of rock is more resilient and less prone to failure in Hong Kong Island's highlands?
Which type of rock is more resilient and less prone to failure in Hong Kong Island's highlands?
What role does the Geotechnical Engineering Office play regarding slope safety on Hong Kong Island?
What role does the Geotechnical Engineering Office play regarding slope safety on Hong Kong Island?
What significant change in mass movement occurrences was noted since 1977?
What significant change in mass movement occurrences was noted since 1977?
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What is a consequence of poor slope maintenance in Hong Kong?
What is a consequence of poor slope maintenance in Hong Kong?
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What is one feature of garden mulching that aids in slope stabilization?
What is one feature of garden mulching that aids in slope stabilization?
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How are drainage systems beneficial in managing landslides on steep slopes?
How are drainage systems beneficial in managing landslides on steep slopes?
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What is an outcome of vegetation on slopes during landslide events?
What is an outcome of vegetation on slopes during landslide events?
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Study Notes
Hong Kong Island Landslides
- Dense Population: Hong Kong Island is densely populated (7 million people in 1075 km²). 230 surrounding islands also exist.
- Landslide History: Frequent landslides, particularly during the rainy season (May-September), due to steep slopes.
- Mass Movement Data (1960s-70s): Natural landslides were less significant than human-related ones (187 natural landslips vs 371 human-related landslips per 100 km²).
- Fatalities: 470 deaths between 1947 and 1997 linked to landslides.
- Geology: Lowlands have sedimentary rock formations, while high ground is granite and volcanic rock. Granite is more prone to weathering and failure compared to the volcanic rock.
- June 1966 Landslide: A major rainstorm event resulted in 64 fatalities, 2500 homes were made uninhabitable, and 8000 people evacuated. It saw 1650 mm of rainfall in 15 days, causing 700 landslides.
- Vegetation Role: Vegetation plays a role - smaller landslides were halted, leading to bigger washouts.
- Causes of Landslides: Excavation, construction, traffic, and steep terrain (up to 30°) are all contributing factors.
- Mitigation Efforts: The Geotechnical Engineering Office manages slope safety systems with 700 workers.
- Slope Database: A catalogue of slopes (57,000 man-made) is maintained for risk assessment and safety protocols installation.
- Enforcement: Private owners face HK$50,000 fines and one-year imprisonment for non-compliance.
- Successes: Landslide risk reduction was successful, with a 50% decrease since 1977. Future risks are rising with construction at higher elevations and tighter spaces.
- Drainage: Drainage systems are implemented to remove excess rainwater, but inadequate maintenance remains a concern/issue.
- Slope Stabilization Methods: Constructing man-made slopes, grading to minimize risk, installing drains and impervious hard coverings are used.
- Greening Techniques (Environmental Friendly):
- Mulching: Creates vegetation protection, helps maintain slope stability, withstands rain erosion, and retains water.
- Long-Rooted Grass: Installed via drilled holes with added fertiliser and soil. Environmentally friendly, cost-effective, and low-maintenance solution for steep slopes.
- Fibre Reinforced: Mixes polyester fibres into the soil to resist tension. Low maintenance, erosion-resistant, good for habitat restoration, and aesthetically pleasing.
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Description
Explore the dangers of landslides on Hong Kong Island, a region grappling with overpopulation and steep terrains. This quiz delves into the incident history, geological factors, and the impact of human activities on landslide occurrences. Understand the significance of rainfall and vegetation in landslide dynamics.
