Disaster preparedness is the first step in any disaster management process. Explain how hazard zonation mapping will help disaster mitigation in the case of landslides.

Preparedness as the first step

• The disaster-management cycle is prevention, mitigation, preparedness, response, recovery. Preparedness is the hinge: plans, maps, stocks, trained people, and public awareness that make the later steps possible.
• The Disaster Management Act, 2005 and National Disaster Management Authority (NDMA) guidelines put hazard, vulnerability, and risk assessment at the front. Without that, a State Disaster Management Plan is a list of phone numbers.
• For landslides, preparedness means: a zonation map, building rules that follow it, drainage and slope works in amber zones, relocation from red zones, early warning (rainfall thresholds, sensors), and community drills. Response (NDRF, SDRF) still matters; it cannot substitute a house built on a debris fan.

What landslide hazard zonation mapping is

• The Geological Survey of India (GSI) and partner agencies prepare macro, meso, and micro zonation: from regional susceptibility to site-specific slope maps.
• Inputs typically include slope angle and aspect, lithology and structure, soil depth, land use and land cover, drainage, rainfall intensity, seismicity, and past slide inventory.
• Output is usually classes such as low, moderate, high, and very high (or similar colour bands). BIS standards and NDMA landslide guidelines tell States how to use those classes in planning.
• Mapping is not a one-time poster. Roads, hydropower cuts, and climate-heavier cloudbursts change susceptibility; maps need update after major events and after new hill cutting.

How the map helps mitigation

• Avoidance: refuse or strictly condition construction, schools, and hydropower camps in very high hazard zones. This is the cheapest mitigation.
• Regulation: hill municipal bye-laws and town-and-country planning can ban multi-storey loads on red slopes and demand retaining and drainage on amber slopes.
• Engineering targeting: limited public money for check walls, rock bolts, catch drains, and bio-engineering goes first to high-hazard inhabited stretches and strategic roads (for example hill National Highways).
• Early warning: couple zonation with India Meteorological Department rainfall thresholds and local piezometers; evacuate only the mapped catchments, not an entire district blindly.
• Insurance and relief norms: premia and ex-gratia can reflect mapped risk so reconstruction is not repeated on the same scar.
• Environmental clearance and road alignment: the map should sit in EIA for hill roads and dams so a new cut does not create the next slide.
• Community mitigation: local people can mark springs and old scars; the scientific map plus panchayat memory is stronger than either alone.

Indian context

• Landslide risk is concentrated in the Himalaya, North-East, Western Ghats, and Konkan / Nilgiri belts. Kedarnath 2013, later Kerala hill events, and repeated slides on NH corridors in Uttarakhand, Himachal, and the North-East show the cost of building without a map.
• National Landslide Risk Management Strategy and GSI’s national programme aim at coverage; many inhabited micro-slopes are still unmapped at the scale a gram panchayat can use.
• Recommendations: finish inhabited micro-zonation, put maps on a public GIS, bind building permissions to them, maintain hill drainage as a yearly budget line, and stop unscientific road widening that steepens toes of slopes.