Why in the news?

  • As per the recent study of the India Meteorological Department (IMD) there is an increasing trend of mini cloudburst.

Mini-Cloudbursts

  • Definition
    • A mini-cloudburst is a localized, high-intensity rainfall event similar to a cloudburst but covering a much smaller area and lasting for a shorter duration.
    • It involves sudden, torrential rainfall (typically >50 mm/hour in a very small area, often less than 10 sq. km).
  • How Different from Cloudburst
    • Cloudburst: Extremely heavy rainfall (>100 mm/hour) over a larger region (20–30 sq. km).
    • Mini-Cloudburst: Occurs in an even smaller pocket (often within a single valley or village) but still intense enough to cause flash floods and landslides.
  • Causes
    • Orographic Lift: Moist monsoon winds rising over mountains (e.g., Himalayas) cool and condense rapidly.
    • Convective Activity: Strong vertical cloud development (cumulonimbus) causes sudden release of moisture.
    • Localized Convergence: Narrow valleys trap moisture-laden air, intensifying rainfall in small zones.
    • Climate Change Factor: Warming atmosphere holds more moisture, increasing frequency of extreme rainfall events.
  • Impact
    • Flash Floods: Sudden rise in river/stream levels in a matter of minutes.
    • Landslides & Soil Erosion: Particularly in Himalayan terrain.
    • Infrastructure Damage: Roads, bridges, power lines often destroyed.
    • Human Casualties: Common in Uttarakhand, Himachal Pradesh, J&K, and parts of the North-East.
  • Examples
    • July 2023: Mini-cloudburst near Amarnath shrine (J&K) caused flash floods and fatalities.
    • August 2024: Himachal Pradesh faced multiple mini-cloudbursts leading to road blockages and flash floods.
  • Challenges
    • Detection Difficulty: Current Doppler radars cannot always capture such hyper-localized events.
    • Forecasting Gaps: Models work at larger scales, but mini-cloudbursts happen at micro-scale.
    • Disaster Response: Limited warning time (often minutes to hours).
  • Mitigation
    • Dense Weather Radar Network: Deploy high-resolution radars and satellite-based monitoring.
    • Early Warning Systems: Community-based alerts using mobile networks.
    • Infrastructure Planning: Avoid settlements on riverbanks, steep slopes, or flood-prone valleys.
    • Disaster Management: Strengthen SDRF/NDRF units in hilly regions, promote evacuation drills.
    • Climate Adaptation: Incorporate extreme rainfall trends in urban and rural planning.
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