- 2075 Baisakh · 2 marks
Relative hazard
Short answer
Relative hazard ranks areas by degree of hazard compared to each other, without absolute probability. It assigns weighted ratings to causative factor classes (slope, lithology, etc.), overlays them in GIS to derive a hazard index, and zones the region from very low to very high hazard.
Describe relative hazard.
Relative hazard assessment ranks the different parts of a region according to their degree of hazard, relative to one another, without giving the exact probability or time of occurrence. It answers "which area is more hazardous?" rather than "how likely is the event?".
Method
- Choose the causative factors (slope, lithology, structure, land use, rainfall, distance to faults and streams, landslide inventory).
- Give each factor class a rating or weight (rating of low, moderate, high).
- Overlay the maps (GIS) and add the weighted values to give a hazard index.
- Divide the region into zones: very low, low, moderate, high, very high.
Uses
- Regional planning and land-use zoning.
- Priority for detailed investigation and mitigation.
- Quick, cheap hazard maps when data are limited.
It is qualitative or semi-quantitative, subjective, and not suitable for exact design.
✓ Answer checked by Claude Opus 5.5 (high effort)