QUES . Enumerate the factors responsible for high frequency and magnitude of landslide in the mountain ecosystem.UPSC IES/ISS EXAM 2022 General Studies . 200 Words . 5 Marks
HINTS:
What is a Landslide?
A landslide is defined as the movement of a mass of rock, debris, or earth down a slope. Landslides are a type of “mass wasting,” which denotes any down-slope movement of soil and rock under the direct influence of gravity.
Landslides are one of the natural hazards that affect at least 15 per cent of the land area of our
country.
What are the factors responsible for high frequency and magnitude of landslide in the mountain ecosystem?
Almost every landslide has multiple causes. Slope movement occurs when forces acting down-slope (mainly due to gravity) exceed the strength of the earth materials that compose the slope.
Causes include factors that increase the effects of down-slope forces and factors that contribute to low or reduced strength. Landslides can be initiated in slopes already on the verge of movement by rainfall, snowmelt, changes in water level, stream erosion, changes in ground water, earthquakes, volcanic activity, disturbance by human activities, or any combination of these factors.
Heavy rain: Heavy rain is the main cause of landslides.
Deforestation: Deforestation is another major cause of landslides. Tree, brushes and grasses keep the soil particles compact. Mountain slope looses their protective cover by felling of trees. The rain water flows on such slopes with unimpeded speed.
Earthquakes and volcanic explosions: Earthquake is a common feature in the Himalaya. Tremors destabilize the mountains and the rocks tumble downwards. Volcanic explosions also trigger landslides in the mountainous areas.
Building of roads: Roads are built in mountainous areas for development. During the process of the construction of road, a large amount of rocks and debris has to be removed. This process dislodges the rock structure and changes the angle of slopes. Consequently landslides are triggered. For example widening of roads under the Char Dham Project and the 6-km Helang-Marwari bypass (under Char Dham Project) may have weakened slopes and further destabilising the local topography leading to Joshimath Crisis.
Shifting agriculture: In the North Eastern part of India, the number and frequency of landslides has increased due to the practice of shifting agriculture.
Construction of houses and other buildings: For giving shelter to the ever increasing population and promotion of tourism more and more house and hotels are being built. In building processes large amount of debris created. This causes the landslides.
Thus, efforts like risk assessment and mapping, early warning systems, capacity building, and emergency response and rehabilitation should be carried out to minimize the occurrence of landslides and mitigate their impacts.
