The widespread flow of rock, rubble, or soil down a slope is simply characterised as a landslide. They are frequently associated with earthquakes, floods, and volcanoes. Furthermore, excessive rains might trigger a landslide, which can obstruct the river’s flow for an extended period of time.
The Himalayas are the result of the Indian and Eurasian plates colliding. The Indian plate’s northward advance towards China generates continual stress on the rocks, making them friable, fragile, and prone to landslides and earthquakes.
The sluggish movement of the Indian crust, roughly 5 cm/year, generates tension, which is ascribed to natural calamities. Some landslides cause one-of-a-kind and unprecedented disasters.
Aside from the Himalayas, the Northeastern hill ranges, the Western Ghats, the Nilgiris, the Eastern Ghats, and the Vindhyans, which cover roughly 15% of the continent, landslides and avalanches are among the primary hydro-geological hazards that threaten huge sections of India.
Based on historical data, frequency, and precise causal links with the governing components such as geology, geomorphic agents, slope, land use, plant cover, and human activities, India has been classified into a number of zones.
This zone comprises the Himalayas, Andaman and Nicobar Islands, heavy rainfall regions with steep slopes in the Western Ghats and Nilgiris, the northeastern regions, and areas prone to ground shaking due to earthquakes, among other things. It also includes areas with a high concentration of human activity, including construction of roads and dams.
This category also includes locations with circumstances that are almost equivalent to those found in the extremely high vulnerability zone. The sole distinction between these two is how the regulating variables are combined, how fiercely and frequently they occur. Except for the Assam plains, all Himalayan and northeastern states are included in the high susceptibility zones.
Landslides occur on occasion in locations that get less precipitation, such as the TransHimalayan areas of Ladakh and Spiti (Himachal Pradesh), undulated yet stable topography and low precipitation areas in the Aravali, rain shadow areas in the Western and Eastern Ghats, and the Deccan plateau. Subsidence and mining-related landslides are most common in Jharkhand, Orissa, Chhattisgarh, Madhya Pradesh, Maharashtra, Andhra Pradesh, Karnataka, Tamil Nadu, Goa, and Kerala.
According to the Disaster Management Act of 2005, the National Disaster Management Authority (NDMA), a statutory and apex organisation chaired by the Prime Minister, is tasked with developing disaster management policies, strategies, and guidelines to enable a fast and efficient response to catastrophes.
A Task Force of Experts has been established to develop a National Landslide Risk Management Strategy. The Task Force was divided into six expert Sub-Groups that addressed various aspects of landslide catastrophe risk reduction.
Landslides can be caused by both natural and man-made factors. Long-term climate changes may have a substantial influence on soil stability. Seismic activity has historically led to landslides across the world. When tectonic plates shift, the earth underneath them moves as well.
Weathering is a natural process of rock degradation that results in weak, landslide-prone rocks. Slope support is eroded by occasional flowing water, such as streams, rivers, wind, currents, ice, and waves, increasing the likelihood of landslides. Landslides can be caused by volcanic eruptions. The stratovolcano is a typical example of a volcano that is responsible for the majority of landslides worldwide.
Mining activities that employ blasting techniques dramatically amplify landslides. The vibrations from the explosives have the potential to harm the soil in other landslide-prone areas. Clearcutting is a type of wood harvesting that entails the removal of all old trees from the region. This procedure is dangerous since it eliminates the local mechanical root system totally.
Property is destroyed due to a landslide. Its renovation and reconstruction cost millions of dollars. A landslide’s powerful flow of mud, debris, and boulders may inflict severe damage to personal property as well as other important infrastructures such as highways, trains, recreational destinations, buildings, and communication networks.
Communities at the foot of hills and mountains are more vulnerable to landslides. Most disaster-prone places are densely inhabited, making life much more difficult. The movement of mud, rock, and debris destroys the natural beauty of a location.
The material carried by landslides obstruct or impede their natural flow. It has a major impact on many river ecosystems, including fish, since it interferes with the normal flow of water. It can result in the diversion of river water, which can cause flooding and property damage.
Communities depending on the river water or coasts for household activities, livelihood, and irrigation will suffer from it. Landslides make the development and other infrastructural projects risky as well as costly, which, in turn, adversely affects the developmental activities in these areas.
It is always advisable to adopt area-specific measures to deal with landslides. Restriction on the construction and other developmental activities such as roads and dams, limiting agriculture to valleys and areas with moderate slopes, and control on the development of large settlements in the high vulnerability zones, should be enforced.
Hazard mapping to locate areas prone to landslides. Hence, such areas can be avoided for building settlements. Some positive actions like promoting large-scale afforestation programs and the construction of bunds to reduce water flow.
Terrace farming should be encouraged in the northeastern hill states where Jhumming (Slash and Burn/Shifting Cultivation) is still prevalent. To warn people residing in landslide-prone areas in advance. Advancement in scientific techniques will empower us to understand what factors cause landslides and how to manage them.
Landslide-related disasters are typically much less dramatic than those brought on by earthquakes, volcanic eruptions, tsunamis, and cyclones, but their effects on the environment and the country’s economy are no less catastrophic. They are mostly influenced by extremely localized factors, in contrast to other disasters that are sudden or unpredictable, and are generally controlled by macro or regional factors.
Therefore, gathering information and keeping an eye on the probability of a landslide is not only challenging but also quite expensive. However, certain mitigation methods can undoubtedly aid in lowering the cause and effect related to them.