https://www.thestar.com.my/news/nation/2024/09/21/landslide-hits-area-near-brinchang-cameron-highlands - the latest news
Following news Source : I look back at the Star (dated 30/01/2024) and found the news which may hold the key and mitigation to the problem)
Excerpt :
According to Natural Resources and Environmental Sustainability Ministry, the Minerals and Geoscience Department has conducted investigation on the site to identify the cause as well as to determine the danger zone and control zone of the incident area to ensure the safety of rescuers while search and rescue operations were carried out.
“The initial investigation found that the cause of this incident was due to continuous rain starting from 3pm on Jan 24 with cumulative daily rainfall reaching 126mm on Jan 25.
"This continuous rain caused the high and steep natural slopes (more than 35 degrees) based on granite rocks to collapse.
"In order to avoid the risk of landslides, the ministry is recommending the local authorities to take into account inputs from the Slope Hazard and Risk Map Production Project (PBRC) in development planning and regulating agricultural activities in slope areas.
My take on this issue
The recent landslide, especially on steep natural slopes, can be triggered by several factors, often in combination.
POSSIBLE PRIMARY CAUSES
1) Heavy and Continuous Rainfall
Excessive rain saturates the soil, reducing its stability. On steep slopes, water infiltration increases pore water pressure, weakening the slope and causing landslides.
2) Steep Slopes
Steeper Slopes are naturally more prone to gravitational instability. When coupled with other factors like rain, they are more likely to fail.
3) Granite Rock Formation
Despite its’ strength, it can have fractures and joints that allow water infiltration. Over time, this can weather and weaken the rock.
4) Deforestation and Land Use Changes
The removal of vegetation (trees, shrubs, etc.) destabilizes slopes as roots help anchor the soil. Tourist development, construction, or logging can exacerbate the risk.
5) Soil Creep and Erosion
Gradual erosion at the base of slopes (due to water runoff, for example) can destabilize the upper parts of the slope over time.
6) Undercutting of Slopes
Construction activities (like road building) that cut into slopes can remove natural support, leading to landslides.
7) Human Activity
Overloading slopes with buildings, infrastructure, or foot traffic can increase pressure on already unstable slopes.
POSSIBLE MITIGATION
To reduce landslide risk in such areas, a combination of engineering, vegetation, and management approaches should be considered.
1) Slope Stabilization and Engineering Solutions
- Retaining Walls - Build retaining structures at the base of slopes to hold back soil and rocks.
- Terracing or Benching - Cut the slope into smaller, less steep sections to reduce the risk of mass movement.
- Drainage Systems - Install proper drainage systems (e.g., French drains, surface ditches) to channel water away from the slopes and prevent water from saturating the soil.
- Rock Bolts and Netting - Install rock bolts and steel mesh netting in areas prone to rockfalls to hold loose rocks in place.
- Vegetation and Reforestation - Replanting Vegetation: Use deep-rooted trees, shrubs, and grasses to help anchor the soil. Native species should be prioritized as they are adapted to local conditions.
- Bioengineering Methods - Use bioengineering techniques like geotextiles, vegetated retaining walls, and planting bamboo or vetiver grass to stabilize the soil.
2) Monitoring and Early Warning Systems
- Rainfall Monitoring - Set up rain gauges and water sensors to monitor critical levels of rainfall that could trigger landslides.
- Geotechnical Monitoring - Use GPS, inclinometers, or landslide sensors to monitor slope movement and detect early signs of instability.
3) Tourism Management and Zoning
- Zoning Restrictions - Limit construction and development in high-risk zones or prohibit building in areas with steep slopes or near active landslide sites
- Tourist Education - Provide tourists with information on landslide risks, especially during heavy rain periods, and establish clear evacuation plans.
4) Regular Slope Maintenance
- Clearing Drainage Paths - Ensure that drains, culverts, and ditches are clear of debris so water doesn’t accumulate.
- Slope Inspections - Conduct routine inspections of slopes and drainage systems, especially after heavy rainfall, to identify early signs of instability.
