Landslide - Reason, Types, Intimation and Awareness.

 

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One of the most catastrophic natural disasters, landslides are a form of mass wasting event in which rock, soil, and other material flow down a slope under the force of gravity. These geological occurrences are especially harmful because they can occur abruptly and without warning and majorly impact infrastructure, human settlements, and landscapes.

What is a Landslide?

Landslides are known as landslips or rockslides. A landslip occurs when a mass of rocks, debris, earth, or soil (a combination of earth and debris) slides downslope. Given the proper soil, moisture, and slope angle, they can appear on any terrain. Natural events like intense rain, strong winds, earthquakes, and volcanic activity can cause landslides. Human activity can also cause them, such as mining, construction, and deforestation.

Reason for landslide

Gravity is the major factor behind a landslip, which occurs when forces acting downslope exceed the strength of the earth's material that creates the slope. when a slope or area of land experiences certain gravity processes, that cause it to become unstable from stable. When the "glue" holding the rock and soil grains on the slope together weakens, the rock loses its ability to withstand the force of gravity pressing down on it. This can be caused by either an increase in the sheer strength of the slope material, a decrease in its sheer strength, or a combination of the two. sheer strength depends on two factors

1. Frictional strength: the resistance to movement between the slope material's interacting constituent particles.

2. Cohesive strength: the bonding between sand grains (high frictional strength) and fine grains (low frictional strength).

Factors causing landslide

The landslide is triggered by some natural erosion, intense rainfall, excavation, an earthquake, stream erosion, changes in groundwater level, volcanic activities, or snow melt, and disturbances by human activities like deforestation, irrigation, mining, and construction. Earthquakes, and shaking can induce landslides underwater. These landslides are called submarine landslide which leads to tsunami that damages coastal areas.

Types of Landslides

Landslides can be classified based on the type of material involved and the manner of movement:

1. Falls: Sudden drops of rock or soil from steep slopes or cliffs.

2. Slides: The movement of a cohesive block of material along a well-defined surface.

• Rotational Slides: Involve the rotation of a mass along a concave-upward surface.
• Translational Slides: Occur along a planar surface, with the mass moving more or less as a unit.

3. Flows: Movement of loose material that behaves like a fluid.

• Debris Flows: Mixtures of water, rock, soil, and organic matter moving rapidly downslope.
• Mudflows: Highly fluid mixtures of water and fine-grained materials.

4. Creeps / Topples: Slow, continual flow of dirt or rock down a slope, generally unnoticed except over lengthy periods.

Intimation of landslide 

• Cracks in slopes

• New seeps or springs in dry areas.

• Cracks, bulges, or depressions in the ground, roads, or pavement.

• Tress and boulders cracking together.

• Soil separating from the foundation.

• Underground utility water or telephone wires break.

• The ground slopes downwards in one direction and may shift its direction.

Calamity and Impacts

 Landslides have far-reaching impacts on the environment, human life, and infrastructure:

Environmental Impacts

• Alteration of Landscapes: Landslides can reshape landscapes by removing soil, rocks, and vegetation, and creating new landforms.

• Loss of Habitat: The destruction of vegetation and soil can lead to the loss of habitats for plants and animals.

• Water Quality: Landslides can introduce large amounts of sediment into rivers and streams, degrading water quality and affecting aquatic ecosystems.

Human and Economic Impacts

• Loss of Life and Property: Landslides can cause fatalities and damage or destroy homes, roads, and other infrastructure.

• Economic Costs: The repair and reconstruction of damaged infrastructure, as well as the loss of productivity, can impose significant economic burdens on affected communities.

• Displacement: People may be forced to leave their homes and relocate to safer areas, leading to social and psychological impacts.

Awareness to prevent

Landslides can be prevented and stabilized through sustainable land management techniques like replanting, grazing, and irrigation. 

Technical solutions like retaining walls, terraces, and drainage systems can be effective in controlling water flow.

Public awareness campaigns and planting trees can help prevent landslides. Limiting future development and construction in landslide-prone areas can also help. 

Implementing early warning systems on slopes can alert individuals to potential landslides, enabling timely evacuation and other protective measures.

Final Draft

Landslides are a complicated natural hazard with serious consequences for the environment, human life, and infrastructure. Understanding the origins and mechanisms of landslides, as well as implementing efficient preventative and mitigation techniques, can help communities lessen the dangers associated with them. We may work towards a safer and more resilient future against landslip threats by combining technical solutions, environmental management, and community planning.