Why Bihar Faces Annual Floods: Causes, Challenges, and Solutions (GS Paper 3, Disaster Management)
Why in News?
- Bihar is grappling with severe floods again, affecting approximately 1.18 million people. Many are displaced and reliant on emergency food supplies and shelter, facing heightened risks of water-borne diseases.
- This annual crisis destroys crops and livestock, perpetuating a cycle of devastation that the state struggles to break.
Bihar’s Vulnerability
Bihar is India’s most flood-prone state, with about 76% of its northern population under the recurring threat of floods. The region is crisscrossed by numerous snow-fed and rain-fed rivers, increasing the risk of various flooding types:
- Flash Floods: Caused by sudden rainfall in Nepal with a short lead time of around 8 hours.
- River Floods: Resulting from overflowing rivers, typically with a lead time of 24 hours.
- Drainage Congestion Floods: Arising from confluences of rivers, developing over 24 hours and potentially lasting the entire monsoon season.
- Permanent Waterlogging: Areas that remain waterlogged year-round due to various factors.
Why is Bihar Prone to Annual Flooding?
The geographic and climatic conditions contribute to Bihar's vulnerability:
- Location: Bihar lies downstream of Nepal, where several Himalayan rivers, such as the Kosi, Gandak, and Bagmati, flow into the state.
- Sediment Load: These rivers carry significant sediment due to the young Himalayan terrain. When rainfall increases river volumes, it leads to overflow.
- Waterlogging Causes: Permanent waterlogging results from siltation, encroachment on drainage channels, and the natural formation of depressions (locally called Chaurs) from changing river courses.
The Kosi Challenge
The Kosi River, often referred to as the "sorrow of Bihar," epitomizes the flood risk. Although embankments were constructed in the 1950s to control its flow, they have been repeatedly breached, creating further complications:
- Sediment Trapping: The embankments have trapped sediments, raising the riverbed by approximately 5 inches annually, increasing the likelihood of overflow.
- Recent Flooding: The current floods have been exacerbated by significant rainfall in Nepal and the release of an unprecedented volume of water from the Birpur barrage on the Kosi, resulting in breaches at multiple locations.
Economic Impact of Bihar’s Floods
While loss of life may not always be severe, the economic ramifications are profound:
- Crop and Livestock Damage: Annual floods devastate agricultural output, threatening food security and livelihoods.
- Infrastructure Loss: Flooding leads to extensive damage to infrastructure, hampering economic activities.
- Relief Costs: The state allocates around ₹1,000 crore annually for flood relief and management, straining resources and limiting developmental initiatives.
Possible Solutions
Addressing Bihar's flooding issues requires a multifaceted approach:
- Dam Construction: Proposals for building a dam on the Kosi River have been on the table for decades, but require cooperation from Nepal, slowing progress.
- Barrage Construction: The Bihar government has called for additional barrages on the Kosi, Gandak, and Bagmati rivers, aiming to improve flood management.
- Engineering and Non-Structural Solutions:
- Engineering Measures: While physical infrastructure is essential, repeated breaches highlight the need for better engineering solutions.
- Non-Structural Approaches: These include implementing laws, enhancing risk reduction strategies, establishing early warning systems, and promoting flood preparedness.
- Flood Atlas Recommendations: Experts suggest focusing on minimizing risks and damages rather than relying solely on structural solutions, particularly for dynamic rivers like the Kosi.
Conclusion
- Bihar's annual flooding is a complex interplay of natural geography and human management.
- While immediate engineering solutions are necessary, a comprehensive strategy that includes preventive measures, community awareness, and international cooperation is crucial to mitigate the impacts of these recurring disasters.
