Assam Floods: Why Ganga-Brahamputra region is flood Prone?

Syllabus: Disaster Management

Source: TH

Context: Six more people died in Assam floods, raising the toll to 58. Over 24 lakh are affected across 30 districts, with rivers flowing above danger levels.

The floods in Assam have led to severe consequences:

1. Loss of Wildlife: Over 130 wild animals, including 6 rare one-horned rhinos in Kaziranga National Park, have died. Other casualties include 117 hog deer, 2 sambar deer, a rhesus macaque, and an otter. Kaziranga hosts the world’s largest population of one-horned rhinos.
2. Infrastructure Damage: Extensive damage to roads and infrastructure has hindered rescue and relief efforts.
3. Displacement of People: More than 2 million people have been displaced, forcing many to seek shelter in relief camps, straining resources and management.

Wha is Ganges-Brahmaputra Delta? 

The Ganges-Brahmaputra Delta, encompassing the states of Assam, Bihar, and West Bengal and covers more than 105,000 km². It stands as a geographical marvel with its intricate river networks. However, this deltaic region is not just a testament to natural beauty but also bears the brunt of annual floods

Key factors contributing to the vulnerability of the Ganges-Brahmaputra Delta to annual floods: 

Natural Factors:

1. Heavy Rainfall and Monsoon Intensity: The region experiences intense monsoon rains, often exceeding 2,500 mm annually, leading to rapid riverine rises and flash floods.
   • Eg: These rivers drain 75% of the total basin runoff in only 3 months of the monsoon.
2. Riverine Morphology: The Brahmaputra River has a highly dynamic and shifting course, prone to erosion and channel avulsion (sudden change in course), increasing flood risks.
   • Eg: The course of the Brahmaputra River has changed dramatically over the past 250 years, of 80 km from east of the Madhupur tract (Bangladesh) to the west of it.
3. Tectonic Activity: The region lies in a seismically active zone, and earthquakes can trigger landslides and disrupt river courses, exacerbating flood events.
   • Eg: Earthquakes of 1897 and 1950 in Assam increased flood frequency in the delta due to subsidence.
4. Tidal influence: The Ganges Delta experiences high tides, creating backwater effects that impede drainage and worsen flood inundation.
5. Cyclonic impact: The delta region is prone to cyclones, with an average of 4-5 cyclones making landfall every year.
   • Eg: 2021 Cyclone Yaas caused massive floods.

Anthropogenic Factors:

1. Deforestation and Land Use Changes: Unsustainable deforestation in the upper catchments increases soil erosion and sediment load in rivers, reducing their carrying capacity and causing overflows.
   1. Eg: Sundarbans flooding attributed to these.
2. Encroachment on Floodplains: Building settlements and infrastructure on floodplains obstructs natural drainage and reduces buffer zones, amplifying flood impacts.
   1. Eg: Bihar floods from are particularly severe due to encroachment of floodplains.
3. Inadequate Drainage and Infrastructure: Insufficient drainage systems, choked rivers, and dilapidated embankments cannot handle excessive water, leading to widespread inundation.
   1. Eg: Inadequate and weak embankments are annually breached in Bihar-West Bengal floods.
4. Poor Urban Planning: Urbanization without proper water management and flood zoning increases runoff and exposes more people to risks.

Strategies can be implemented to mitigate the risks associated with these floods:

1. Early Warning Systems: Implement advanced early warning systems to provide timely alerts to communities, enabling them to evacuate and take preventive measures.
   • Eg: Flood Early Warning System (FLEWS) in Assam by its state disaster management authority.
2. Eco-Restoration: Undertake comprehensive eco-restoration initiatives, including reforestation and wetland conservation, to enhance natural drainage systems and reduce vulnerability.
   • Eg: Red River Delta Rehabilitation Project restored over 100,000 hectares of mangroves and wetlands which can be replicated here.
3. Infrastructure Development: Invest in resilient infrastructure, such as embankments, flood shelters, and drainage systems, to protect communities and vital assets.
   • Eg: Coastal Embankment Improvement Project (CEIP) in Bangladesh part of the delta.
4. Community Engagement: Foster community-based initiatives for flood preparedness, including training in disaster response, and involve local communities in planning and decision-making processes.
   • Eg: Community Preparedness and Adaptation of “Living with Floods” under Flood Risk Mitigation and Management.
5. Climate-Resilient Agriculture: Promote climate-resilient agricultural practices and crop varieties to minimize the impact of floods on the agrarian economy.
   • Eg: Integrated Rice-Fish Farming System (IRFFS) promoted by the World Food Programme.

NDMA Guidelines for Floods:

Conclusion:

As seen above, many factors are natural and inevitable to certain extent, thus, mitigating the risks associated with annual floods in the Ganges-Brahmaputra Delta requires a holistic and integrated approach that combines physical infrastructure, sustainable land-use practices, community engagement, and international cooperation.

Insta Links: 

1. Assam Floods

Prelims Link: