(a) Landslide is a major problem in Himalayan region. Discuss its causes and mitigation measures. 20 (b) Appraise why drought is…

(a) Landslides in the Himalaya: causes and mitigation

A landslide is the downslope movement of rock, debris or soil under gravity. The Himalaya is the most landslide-prone mountain region in India.

Natural causes: young, folded and fractured rocks with weak lithology; steep slopes; very heavy monsoon rainfall and cloudbursts that saturate the slope; frequent earthquakes in seismic zones IV and V; and river undercutting at the toe of slopes. Glacial lake outbursts and snow melt add to the risk.

Human causes: deforestation, which removes root binding; road building by cutting slopes without support; unplanned construction of towns and hydropower tunnels; mining and quarrying; overgrazing; and tourism pressure, as seen in the Kedarnath disaster of 2013, the Char Dham road works, Joshimath subsidence (2023) and the Himachal monsoon losses of 2023.

Mitigation:

• Hazard zonation and susceptibility mapping by the Geological Survey of India, with land-use rules that bar building on unstable slopes.
• Early warning from rain and slope sensors, with community drills and evacuation plans, under the NDMA landslide guidelines.
• Engineering measures: retaining walls, rock bolts, benching, gabions, and proper drainage of surface and subsurface water.
• Bio-engineering: afforestation, vetiver and shrub planting on slopes.
• Scientific road design, regulated tunnelling, and carrying-capacity limits for tourism and hydropower.

(b) Why drought is among India's commonest climatic extremes

India's rainfall depends on the south-west monsoon, which is highly variable in time and space.

Reasons: the monsoon is erratic, with long breaks, delayed onset and early withdrawal; El Niño years often reduce rainfall; rainfall variability is large in west Rajasthan, Gujarat, the Deccan interior and Rayalaseema. About half of the net sown area is rainfed, so crops depend on rain. Nearly two-thirds of the net sown area is vulnerable to drought in varying degrees, and about 16 per cent of the country's area is drought-prone (NDMA), with notable droughts in 1987, 2002, 2009 and 2014–15.

Human factors add to it: over-use of groundwater, deforestation, loss of tanks and wetlands, and poor soil moisture management. Climate change is making dry spells and heavy rain events more common, so that droughts and floods can occur in the same season.

Remedies include watershed development, micro-irrigation, drought-tolerant crops, crop insurance, and timely forecasts and relief.

(c) Ecological and economic challenges of river linking

The National River Linking Project plans about 30 links, 14 Himalayan and 16 peninsular, to move water from surplus to deficit basins; Ken–Betwa is the first to be approved.

Ecological challenges: submergence of forests and wildlife habitats (Ken–Betwa affects the Panna Tiger Reserve); change in river flow and sediment, which hurts fisheries, wetlands, floodplains and delta ecosystems and increases salinity in estuaries; risk of waterlogging and spread of invasive species or diseases; and effect on groundwater recharge. Many "surplus" rivers have no surplus in the dry season.

Economic challenges: very high cost and long gestation; displacement and loss of land and livelihoods of many families; inter-State disputes over water sharing; energy needed to lift water; and uncertain benefits against cheaper options such as watershed management, efficient irrigation and demand management. Any link therefore needs hydrological, environmental and social studies, and State consent, before it is built.