Why Assam is experiencing unprecedented flooding this year, Pg11

Key Highlights:

• Assam is experiencing unprecedented floods, affecting over 6.54 lakh people across 10 districts and claiming at least 66 lives.
• The Upper Assam districts of Sivasagar, Charaideo, and Jorhat are among the most severely impacted.
• Initial government attribution to a "cloudburst" in Nagaland was clarified by meteorologists as heavy rainfall (137 mm over 8-9 hours).
• Major rivers like Dikhow, Dhansiri, Disang, Janji, and Darika, all Brahmaputra tributaries, flowed above danger levels.
• Experts attribute the severity to a combination of extreme weather events, climate change, and anthropogenic factors like mining and deforestation.

Assam Floods.jpg

Detailed Insights:

• Floodwaters reached critical levels on July 19, leading to over 7 lakh people initially affected and 1.15 lakh moving to relief camps.
• The Assam State Disaster Management Authority (ASDMA) reported 6.54 lakh people affected across 810 villages as waters receded.
• Receding floodwaters left behind several feet of sediment, hindering government access to parts of Sivasagar district.
• Heavy rainfall in Nagaland and Assam's Charaideo district on July 18-19 caused rapid water level rises, exacerbated by the already swollen Brahmaputra.
• Climate change is increasing the frequency of high-intensity rainfall events (over 50 or 100 mm in a day) that cause floods.
• Excessive excavation, likely due to mining, on river valley sides contributes to mud flow, reducing river carrying capacity.
• Deforestation in watershed areas leads to rapid runoff and increased siltation, raising riverbeds and further reducing carrying capacity.

Key Concepts Involved:

• Cloudburst: A sudden, localized, and intense rainfall event, typically exceeding 100 mm per hour over a small area.
• River Carrying Capacity: The maximum volume of water and sediment a river channel can transport without overflowing its banks.
• Watershed Areas: Regions of land where all water drains into a common outlet, such as a river, lake, or ocean.
• Anthropogenic Factors: Environmental changes or pollutants caused or influenced by human activities.