Landslide

A landslide is a highly dangerous phenomenon where rocks, soil, or debris slide down a mountain slope or hill, or even a geological layer. It can be triggered by factors like heavy rain, earthquakes, or human activities.

Causes #

Natural factors #

Natural factors, such as heavy rainfall, floods, earthquakes, snowmelt, temperature changes, and strong winds, have a significant impact on the occurrence of landslides. These factors can weaken the stability of slopes and increase the likelihood of landslides.

• Heavy rain: Heavy rain saturates the soil, reducing its strength and cohesion. The excess water increases the weight on the slope, making it more susceptible to sliding.
• Floods: Floods can erode the base of slopes, destabilising them. The rushing water removes the support at the bottom of the slope, leading to slope failure and landslides.
• Earthquakes: Earthquakes shake the ground, disturbing the balance of forces and triggering landslides. The seismic activity can cause the slope to lose its stability and collapse.
• Snowmelt and temperature changes: Snowmelt and temperature changes impact slopes by increasing pore water pressure and weakening the soil. As the snow melts or temperatures fluctuate, the water infiltrates the soil, reducing its strength and making it more prone to landslides.
• Strong winds: Strong winds push against slopes, destabilising them. The force exerted by the wind can cause the slope material to shift and slide, resulting in a landslide.

Human activities #

Human activities can have a significant impact on slope stability.

• Mining: Mining operations can disrupt the natural stability of slopes by removing large amounts of soil and rock. Excavations and underground tunnels can weaken the surrounding slopes, making them more prone to sliding. Poorly managed mining activities can also lead to the accumulation of waste materials, further exacerbating the risk of landslides.
• Improper construction: Improper construction practices, such as inelegant slope design, insufficient drainage systems, or the use of unsuitable materials, can compromise slope stability. Poorly constructed retaining walls or structures can fail under the weight of the soil, triggering landslides. Insufficient planning and engineering can also result in increased erosion and water infiltration, weakening the slope.
• Deforestation: Tree roots play a crucial role in anchoring the soil and providing stability. Deforestation can lead to increased water runoff, soil erosion, and decreased cohesion of the soil, making slopes more susceptible to sliding.
• Land use changes: Alterations in land use, such as urbanisation or agricultural activities, can modify the natural landscape and slope conditions. Construction of buildings, roads, or infrastructure on slopes can disrupt the natural drainage patterns, increase water runoff, and disturb the balance of forces within the soil. Changes in land use can also lead to the removal of vegetation cover, further compromising slope stability.

Other factors #

• Impact of animals: While the impact of animals on slope stability and landslides is generally minimal compared to natural factors and human activities, certain animals can indirectly contribute to slope destabilisation.
  • Burrowing animals: The activities of burrowing animals, such as rodents or groundhogs, can indirectly undermine slope stability.
  • Ants and termites: The excavation of tunnels by ants and termites can weaken the structure of the soil on slopes, compromising their stability.
  • Livestock grazing: Excessive grazing of livestocks can result in the removal of vegetation cover on slopes, increasing the risk of soil erosion and landslides.
• Geographical characteristics: Certain geographical characteristics can indicate a higher susceptibility to landslides. These include areas with steep slopes, weak soil, sandy soil, clay soil, fragmented rock, or soil that experiences changes in water levels.
  • Steep slopes: Areas with steep slopes are more prone to landslides due to the increased gravitational force acting on the soil or rock.
  • Weak soil: Soil with low shear strength or cohesion is more susceptible to landslides as it lacks the ability to resist the downward forces acting on it.
  • Sandy soil: Sandy soil, characterised by loose particles with poor cohesion, is prone to landslides, especially when saturated with water.
  • Clay soil: Clay soil has a high water-holding capacity, which can increase pore water pressure and reduce its strength, making it susceptible to landslides.
  • Fragmented rock: Areas with fragmented or weak rock formations are more prone to landslides as the individual rock pieces can easily dislodge and slide.
  • Soil affected by water level changes: Changes in water levels, such as from heavy rainfall or fluctuating water tables, can significantly impact slope stability. Soil that is affected by these water level changes becomes saturated, reducing its strength and increasing the likelihood of landslides.

Impacts #

• Impact on human life: Landslides can lead to forced displacement of residents and disrupt their daily lives. It can result in the loss of livelihoods, weaken the local economy, and cause social instability.
• Environmental degradation: Landslides can result in the loss of vegetation cover and expose bare soil. This can increase the risk of erosion, sedimentation in rivers, and degradation of water quality.
• Secondary hazards: Landslides can trigger secondary hazards such as mudflows, flash floods, and tsunamis. These hazards can compound the impact and increase the risk to human life and infrastructure.
• Disruption of services: Landslides can disrupt essential services such as electricity, water supply, and communication networks. This can further impede rescue and recovery efforts, as well as impact the daily lives of affected communities.
• Economic losses: Landslides can result in significant economic losses. The destruction of infrastructure, property, and crops can lead to high costs for repairs and recovery. Additionally, landslides can disrupt transportation routes and impact trade and commerce.
• Long-term consequences: Landslides can have long-term consequences on the affected areas. The recovery process can be slow and costly, and communities may struggle to rebuild their lives and regain their livelihoods. In some cases, landslides can lead to permanent changes in the landscape and require adaptive measures for future risk reduction.

Preventive measures #

• Flood and landslide prevention: Constructing drainage systems, planting forests, and implementing environmental protection measures to reduce the impact of floods and landslides. Pay attention to build appropriate landslide prevention structures based on the local terrain and conditions.
• Minimise landslides: Implement measures to protect the ground surface, maintain infrastructure such as drainage systems, ditches, and adjustable dams to minimize the impact of landslides.
• Construct safe buildings and structures: Construct buildings and structures with sturdy designs, follow safety construction regulations, especially in areas with high landslide risk.
• Land management: Implement careful land management, limit excessive mining, illegal tree cutting, forest burning, and follow regulations on land use.
• Monitoring and warning: Regularly monitor and warnings about landslides, use technologies and sensors to detect early signs of landslides and alert the risk.
• Enhance community awareness: Strengthen education, communication, and raise awareness within the community about landslide risks, coping strategies, and prevention measures.