Rain And Landslides In Sikkim

ALOK K. SHRIVASTAVA

Torrential rain across the state for three to four days, just ahead of the 50th anniversary of Sikkim becoming the 22nd State of the Indian Union, has caused widespread disturbance and havoc, including:

• Overflow of water in residential and market areas
• Damage to roads and accumulation of slush and mud
• Emergence of potholes leading to vehicle skidding and minor accidents
• Overflow of seasonal kholas and nallahs
• Traffic disruptions, adversely affecting tourism
• Choking of culverts and causeways
• Vehicles, both small and large, slipping off roads
• Damage to Bailey bridges
• Choking of urban drainage systems
• Large boulders (dungas) precariously hanging over roads and residential areas

Torrential rain—such as what is occurring now in Sikkim or during the monsoon season—often leads to landslides, landslips, rockslides, or mudflows. Such downslope movement of rocks, soil, and debris is not unusual; it has been occurring for years.

Landslides may occur in a variety of environments and are not isolated incidents—they are very much a part of the human environment.

In earlier times, a wireless message had to be sent from the district after such disturbances, requesting a bulldozer or earthmover. Today, JCBs are often available at nearby construction sites or even next door, making repair and restoration easier. The system of first responders at the panchayat or village level has also proven to be highly effective.

Landslides may be caused by intermittent or torrential rainfall, earthquakes, or construction activities (e.g., roads, power, or irrigation projects). On the other hand, overexploitation of earth’s resources—such as mining and deforestation—not only causes but also aggravates the situation. Global warming may also be an accelerating factor.

WHAT ACTUALLY HAPPENS?

Landslides generally occur when sufficient rainwater percolates into the earth mass. This affects the natural drainage and leads to severe damage to agricultural fields, homes, schools, roads, and livestock.

A landslide typically results in a rise in both surface and groundwater levels. Increased hydrostatic pressure in cracks, erosion at the top of slopes, and the sudden formation of waterfalls or rivulets further worsen the situation.

CAUSES RESPONSIBLE

Understanding the natural causes requires examining rock layers and the water discharge patterns. Notably, many old slide points—such as LekhoBir and Birik in Kalimpong District, and 9th Mile, Rangrang, and some areas between Melli and Jorethang—have stabilised over time.

Man-made causes include deforestation, cultivation, construction, blasting, vibration from machinery, and mining activities.

IMPACT OF LANDSLIDES

• Tremendous loss of life and property
• Damage to critical and expensive infrastructure
• Alteration of landscapes
• Disruption of transport services
• Damage to ecosystems and wildlife habitats
• Adverse effects on agriculture, horticulture, and animal husbandry
• Significant economic losses
• Displacement of people and sometimes institutions
• Changes in water sources
• Increased flood risk

HOW TO PREVENT & CHECK LANDSLIDES?

• Use of satellites and thermal imaging
• Installation of early warning systems (with or without cameras)
• Better land use planning
• Slope stabilization
• Fixing rock bolts and ground anchors
• Timely diversion of surface water
• Absorption of excess water
• Regular cleaning and maintenance of drainage systems
• Construction of piles and strong retaining walls
• Planting trees, shrubs, and grasses to bind the soil
• Preservation of existing vegetation to maintain soil stability
• Minimising alterations to natural slopes

RESPONSE AT NATIONAL LEVEL

Initially, natural disasters like landslides were addressed by the Ministry of Agriculture. However, the responsibility was later transferred to the Ministry of Home Affairs to keep pace with evolving scientific knowledge.

By 2005, the National Disaster Management Authority (NDMA) was set up under the Ministry of Home Affairs. State Disaster Management Authorities (SDMAs) were subsequently established in a big way. 

WORK AT MANGAN

Thanks to NDMA’s interest and intervention, Mangan Bazar was saved from sinking. Techniques such as piles, bolts, improved retaining walls, and water diversion were successfully implemented. Past disasters caused by rising waters in Raphong and Lanthekholas no longer occur. Mangan and Sighik now appear to be stabilised.

NATIONAL DISASTER RESPONSE FORCE (NDRF)

To ensure rapid response, the National Disaster Response Force (NDRF), with counterparts in all states, was established.

Today, not only rescue and relief operations are swift, but mitigation measures are also undertaken on priority.

Well-equipped and highly trained, NDRF personnel are deployed internationally as well—in countries such as Türkiye, Myanmar, and Nepal. They have the capability to set up field hospitals within two to three days.

Their tireless service during the COVID-19 pandemic, in close coordination with the Health Ministry and state governments, is a testament to their dedication.