Why Assam is experiencing unprecedented flooding this year

📌 Summary:

• At least 66 lives lost in about a week, nearly seven lakh people affected across 856 villages in 12 districts, and the government yet to reach over 50,000 people for relief — Assam is facing an unprecedented flood wave
• Worst-hit are the Upper Assam districts of Sivasagar, Charaideo and Jorhat; entire villages, farmland and towns like Sivasagar are inundated with water above chest level; 58 deaths (including six children) recorded by ASDMA since Monday, toll likely to rise
• Over 1.15 lakh people are in relief camps; ~4,455 evacuated by boat by NDRF, Army, SDRF and Fire & Emergency Services
• Cause / mechanism: Brahmaputra tributaries — Dikhow, Disang and Dhansiri — flowed well above danger levels in a "severe flood situation"; the swollen Brahmaputra blocked drainage of these tributaries
• The government first blamed a "cloudburst" in Nagaland's Mon (July 19), but a Meteorological Centre Kohima scientist clarified it was heavy rainfall of 137 mm over 8–9 hours, not a cloudburst (IMD defines cloudburst as >100 mm in one hour); the rain also triggered landslides in Mon, killing nine
• Extreme rainfall anomalies: departures of 436% in Charaideo and 493% in Mokokchung on July 18–19; the CM called the speed of the water rise "unprecedented"; receding water left several-feet-high sediment, blocking access
• Experts note climate change is raising the frequency of high-intensity rainfall events

🎯 UPSC Relevance: GS3 Disaster Management — flood risk and vulnerability, riverine flooding in the Brahmaputra basin, climate change and disaster response capacity.

📝 Prelims Facts:

• IMD defines a "cloudburst" as rainfall exceeding 100 mm within one hour
• Brahmaputra tributaries in flood: Dikhow, Disang, Dhansiri
• Agencies in response: NDRF, SDRF, Army, ASDMA (Assam State Disaster Management Authority)

🔑 Key Term: Cloudburst — a sudden, very heavy rainfall event, defined by the IMD as more than 100 mm of rain in one hour over a small area.