What caused the flash flooding that swept through village in India's state of Uttarakhand? | DW News

Key Concepts:

• Mudslide/Flash Flood: A rapid inundation of an area with mud and water, often caused by heavy rainfall or glacial lake outburst.
• Cloud Burst: An extreme rainfall event with over 100mm of rain in a very short period (around an hour).
• Glacial Lake Outburst Flood (GLOF): A sudden release of water from a glacial lake, often due to dam failure.
• Climate Change Fingerprint: The identifiable influence of climate change on extreme weather events.
• Early Warning Systems: Systems that provide timely alerts to residents for evacuation during disasters.
• Land Use Zoning: Planning regulations that designate areas for specific uses, such as no-construction zones near rivers.
• Ecological Sensitivity: The degree to which an ecosystem is susceptible to disturbance or degradation.
• Internal Variability/Natural Monsoon Circulation: Natural fluctuations in weather patterns, distinct from climate change.
• Global Drivers: Large-scale climate factors influencing regional weather.
• Local Amplifiers: Local conditions that exacerbate the impact of global drivers.

Uttarakhand Mudslide/Flash Flood

• Incident Overview: A mudslide in the Himalayan village of Darali, Uttarakhand, India, caused by heavy downpour and potential flash flooding, resulting in at least four deaths and many missing.
• Damage: The mudslide swept through the village center, destroying homes, roads, about a dozen hotels, and a local market.
• Response: The Indian army and police launched a search and rescue operation, coordinating with various agencies, including the Tibetan police and the National Disaster Response Force. The National Disaster Management Authority requested three helicopters for assistance.
• Challenges: The search and rescue operation is hampered by difficult and remote terrain.

Causes and Contributing Factors

• Initial Assessment vs. Data: Initially suspected as a cloud burst, but data is lacking to confirm (requires >100mm rain/hour). Glacial lake outburst is also a possibility.
• Rainfall Patterns: The Himalayan foothills had deficit rain earlier in the season, followed by a sudden shift to excess rainfall.
• Large-Scale Moisture Confluence: Warming in the Middle East and Mediterranean pulls winds over the Arabian Sea northward, pushing moisture into the Himalayan foothills. Flow from the Bay of Bengal also contributes moisture.
• Climate Change Role: Climate change is a factor, as warming in the Middle East and Mediterranean (a direct response to increasing greenhouse gases) impacts monsoon circulation.
• Internal Variability Amplification: Natural monsoon circulation patterns are amplified by global warming.
• Local Amplifiers (Human Activities): Unregulated construction, deforestation, and unplanned settlements in ecologically sensitive areas exacerbate the impact.

Dr. Ragu Morta Goodday's Perspective (Earth System Scientist)

• Deforestation and Unplanned Settlements: "When we have global drivers like global warming bringing in remote effects, we have local amplifiers and these amplifiers are all our human activities. People are settling down in slopes in a you know unplanned and sometimes dangerous way. Deforestation is happening."
• Need for Hyperlocal Risk Maps: "So we need very hyperlocal risk maps which is what we need to make progress on right now."
• Identifying Hotspots: Focus on identifying and managing risks in areas repeatedly affected by landslides and flash floods.

Dr. Aditi Mukaraji's Perspective (Human Geographer)

• Cloud Burst/GLOF: The event was likely a cloud burst (extreme rainfall) or potentially a glacial lake outburst flood.
• Climate Change Fingerprint: "Both of these uh either it's a glacial lake outburst flood or a cloud burst event often increasingly have a climate change fingerprint."
• Increasing Extreme Events: Climate change is playing an increasingly important role in extreme events worldwide, including floods, droughts, and heat temperatures.
• IPCC Report: The latest IPCC report shows that with every increment in global warming, there are more extreme events.
• Vulnerability of Mountainous Areas: Mountainous areas are particularly vulnerable due to difficult terrain.
• Early Warning Systems: "Some of the lowhanging fruit that can be done are uh system of early warning systems. So that actually warns the residents for evacuation in a timely manner."
• Land Use Zoning: "So much of the houses were constructed so near the river and those are all the places that should should have been ideally a no construction zone."
• Communication and Preparedness: Increased communication efforts by the government and local administration to raise awareness and promote preparedness.

Conclusion:

The Uttarakhand mudslide was likely caused by a combination of extreme rainfall (potentially a cloud burst or GLOF) and pre-existing vulnerabilities. Climate change is playing an increasing role in such events, both directly through altered weather patterns and indirectly by amplifying natural variability. Local factors like deforestation, unregulated construction, and lack of proper land use planning exacerbate the impact. Key strategies for mitigating future disasters include implementing early warning systems, improving land use zoning, and increasing public awareness and preparedness. Hyperlocal risk maps are needed to effectively manage risks in vulnerable regions.