Causes for recurring floods in NE India
Natural Causes
- Geography and topography: Entire Northeast India is a flood-prone zone due to its geographical and topographical region making it one of the highest rainfall zones in the world.
- Additionally, Assam, the Gateway of North East India, is crisscrossed by a number of major rivers originating from lower Himalayan ranges and debouching into the plains causing flash floods in the flood plains of Assam and neighboring states.
- Shifting river course: Rivers in the North East are characterized by shifting course frequently due to meandering and flows through several channels. Hence, one can never predict when floods will strike. Eg. Kumutiya river has shifted 3 km since 1960 and an entire village has had to shift with it.
- High silt and braided channel: The rivers on their courses are joined by various streams and tributaries which bring huge silt from the upper catchment area, which shallows the depth of the river bed, clogs the mouth of streams that forms braided channels, which leads to drainage congestion and flooding.
Anthropogenic Causes
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- Weak embarkments: Standing Committee on Water Resources (SCWR) observed that most of the embankments, constructed on the main stem of the Brahmaputra and its tributaries, date back to the 1960s and 70s which are weak and causing floods.
- Encroachment of riverine areas: The flood plain of a river is essentially its domain and any intrusion into or developmental activity therein obstructs the river’s ‘right of way’ leading to frequent severe floods.
- Deforestation and destruction of wetlands: Trees and wetlands have the ability to reduce runoff, but deforestation and destruction of wetlands for development reasons have intensified the erosion process by rivers and caused floods.
- Climate change: India has been witnessing a surge in extreme weather events associated with the lethal impact of climate change like heatwaves and strong low pressure over the Bay of Bengal that resulting into
sheer volume of early rain by strong south-westerly winds. - Lack of inter-state cooperation: According to the SCWR report, Lack of cooperation among States in respect of inter-state projects, and difficulty in implementation of flood plain zoning, and regulations are some of the problems faced in checking the recurring floods in Assam and North East (NE) region.
Measures needed to be taken for flood management in North East India.
- Structural measures
- Construction of reservoirs: Flood storage and integrated reservoir operations are required along with the construction of storage reservoirs on the tributaries and distributaries.
- Strengthening embarkments: The Standing Committee on Water Resources (SCWR) stated the need to strengthen and raise embankments with bank protection measures in form of revetment or Reinforced cement concrete (RCC) porcupines.
- Dredging rivers: Dredging of river beds helps in increasing the water-holding capacity of the rivers, addressing erosion by silt accumulation, and reducing the intensity of floods.
- Weather stations: Set up modern weather stations in the upstream catchment of all dams in the North East and install sirens on river banks near dams. This would alert downstream populations in the event of floods.
- Administrative measures
- North East Water Management Authority (NEWMA): Setting up an apex body involved in the implementation and monitoring of all projects related to hydro-power, bio-diversity conservation, irrigation, flood control, inland waterways, forestry, fishery, and eco-tourism in all north-eastern states.
- River Basin Organizations (RBO): Setting up RBOs would effectively provide immediate, short-term, and long-term solutions in addition to the overall development of the river basins, which effectively help in the integrated basin management and minimize flood situations.
- Flood Plain Zoning: Flood-plain zoning measures aim at demarcating zones of floods of different magnitudes or frequencies and specify the types of permissible developments in these zones so that whenever floods actually occur, the damage can be minimized.