Landslide is one type of a natural disaster in which a mass of rock, soil, or debris moves down a slope. The occurrence of landslides usually happens in mountainous or hilly areas, generally causing severe destruction to infrastructure, human life, and property. Landslides always come during the rainy season, typically making mountainous regions less accessible to humans. The main causes of landslides can be divided into either natural operations or human-oriented operations.
| GS Paper | GS Paper I, GS Paper III |
| Topics for UPSC Prelims | Basic Concepts of Disaster ManagementLandslide Zonation Mapping |
| Topics for UPSC Mains | National and State Policies on Disaster Management, Role of NDMA , Landslide Mitigation |
A landslide is movement of mass rock, earth, or debris down slope. This natural disaster occurs if the stability that maintains a slope is destroyed, thus causing such material to slide off or fall. Landslides may occur as a result of heavy rainfall, earthquakes, volcanic activity, or deforestation and construction activities. They can be fast and cause severe destruction in property, structures, or loss of human life.
Types of Landslides are various types of mass movements of soil, rock, or debris down a slope. These types vary based on the material involved and patterns of movement, ranging from rapid rockfalls to slow-moving soil creeps.
There are rockfalls which happen when loose rocks fall away from the steep slope or cliff because of weathering, erosion, or sudden disturbances such as earthquakes. The falls are completely free falling through the air, accumulating speeds. It is mainly fast and potentially very destructive, mainly when the falling rocks hit buildings, roads, or people at the bottom.
Debris flows is the flow of loose soil, rock fragments, organic material, and water down a slope. Such movements are triggered through heavy rainfall melting snow, or volcanic activity. Extremely dangerous, debris flows travel fast, covering huge distances, causing destruction across areas, uprooting homes, roads, and vegetation.
Slow-moving earth flows with a mix of fine-grained soil and clay with silt, water. They have gento-moderate slopes, but they acquire a more or less curved appearance, flow-like. They change the landscape by depositing material downslope, especially slowly over considerable time. Though slow, their gradual destruction is destructive to roads, buildings, and agricultural land.
Slumps have the characteristics of downward and outward rotation of rock or soil with a curved ground surface. This type of landslide leaves a series of terraces or steps as material moves in blocks. Slumps are very common on over-steepened slopes through erosion or even construction processes and can cause serious damage to structures and roadways.
It is the slow, gradual movement of soil, rock, or debris down a slope. Creep occurs due to various factors, such as freeze-thaw cycles and soil moisture fluctuations, or gravity is acting on unstable slopes. Creep can be impossible to monitor on a day-to-day basis, although creep can wreak havoc on a building’s structural integrity over time. Trees lean, pole heights diminish, fences move, and building foundations crack.
Heavy rainfalls, earthquake, volcanic activities, and fast melting of snow are some of the natural elements that contribute to landslide events that cause slope softening. However, there is a very important contribution from humankind.
For a long or heavy precipitation, the soil on slopes will saturate and become heavy; it slides due to loss of strength and friction properties. This disables the soil and rocks from holding themselves with much force, and they start sliding down along the slippery layer of mud created by saturation.
Earthquakes may trigger sudden ground movements that destabilize the slopes, thus causing landslides. Shaking in the form of ground movement dislodges rocks, soil, and debris, making them liable to sliding. Even slight shaking can release huge landslides from mountainous regions if the slopes have been weakened by factors such as deforestation.
Trees and other vegetation species stabilize the soil. It, therefore, becomes a human influence when forests are cleared for agricultural purposes, urbanization, or logging. The roots that stabilize the soil are dug up in this process. The soil is exposed and loose. The soil is quickly susceptible to flooding and eventually sliding.
Roods, constructions, and many other infrastructures in steep slopes usually bring about soil instability. Trenching from excavations mining as well as other land scaping tends to destroy the natural stratum of the earth; therefore it greatly reduces the strength of the slope. Poor planning of the use of land, lack of drainage, and uncontrolled construction enhance the probability of landslides.
Volcanic eruptions shake the ground, melt snow, and release volcanic debris, all which can cause landslides. The heat from an eruption may melt the ice and snow on the slopes of a volcano, resulting in vast amounts of water, mud, and rocks streaming downhill that then cause widespread landslides and destruction.
This landslide effect may be disastrous, destroying houses and roads together with infrastructure facilities, meaning a heavy loss on the economic side. The effect of landslide can cause injuries or even death, plus result in the mass devastation of communities.
Generally, many landslides cause a great loss of human life; fast-moving debris, rocks, and soils engulf homes, vehicles, and humans, and rescue operations may be challenging in landslide-prone areas because roads are blocked and conditions are unstable, which increases the death toll aggravating survivors’ psychology.
The landslide causes deforestation and loss of vegetation along with soil erosion. This changes the natural landscape, creates disruption in local ecosystems, and interference in habitats of wildlife. It also reduces land fertility and leads to less agricultural usage in any area due to the removal of the topsoil. Apart from this, a landslide can alter the course of rivers, which leads to flooding and affects the supply of water available in the area.
The economic impact of landslides is more profound. This is because they destroy infrastructure like roads, bridges, and utility systems, and also interrupt the daily life and business of people. The cost of repairing, reconstructing, and rehabilitating affected communities can be high. Landslides can also lower tourism, which impacts the income of those dependent on tourist activities.
Landslides cut many roads, railways, and communication routes that separate affected areas from aid support. Such cases hinder an immediate response to emergencies; delivery of aid is also delayed, which makes it difficult for people to be evacuated from affected areas. Long-lasting isolation leads to food and medical supply shortages, and the case worsens while delay proves to hinder recovery processes.
Landslides may cause obstruction of rivers and build natural dams. These dams eventually may lead to the formation of lakes and are often prone to sudden flooding in case a break in the dam occurs. This may have resulted in greater downstream flooding and put many lives and properties at risk miles away from the original site of the landslide and multiplied the damage created by the disaster.
Managing landslide risks encompasses several methods. Growing trees on slopes helps stabilize soil in the presence of roots and restricts water from infiltrating deeper. Construction of retaining walls prevents soil from sliding.
Landslide is a natural hazard which poses serious threats of life, property, and the environment too. Understanding what a landslide is, its causes of landslide, and its effects of landslide can help mitigating the impact of landslides. Awareness, proper land management, and early warning systems have always played a crucial role in avoiding tremendous devastation caused by landslides.
| Landslides UPSC Notes |
| 1. Landslides are natural disasters involving the downward movement of rock, earth, or debris along a slope. 2. They are triggered by factors like heavy rainfall, earthquakes, volcanic activity, deforestation, and human activities like mining. 3. Landslides lead to loss of lives, property, and infrastructure, severely impacting human settlements in hilly regions. 4. They disrupt transportation and communication networks, causing economic setbacks, especially in remote and mountainous areas. 5. Prevention and mitigation include slope stabilization, afforestation, proper drainage systems, and monitoring vulnerable regions. 6. Warning systems, early detection through satellite imagery, and public awareness can reduce landslide-related damages. 7. Government policies focus on risk assessment, hazard mapping, and community-based disaster preparedness to tackle landslides. 8. Sustainable land-use practices and avoiding construction on steep slopes are crucial in reducing landslide occurrences. |
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