Kabartal Wetland: The oxbow lake of India

The Kabartal Wetland (locally known as Kanwar lake) is Asia’s largest oxbow lake situated in the Begusarai district of Bihar. It is a residual oxbow lake, formed due to the meandering of Gandak river, a tributary of Ganga. Covering the majority of the Indo-Gangetic plains in northern Bihar, this lake was declared a Ramsar site in 2020, making it the first wetland in Bihar to be included in the Ramsar convention.

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Top view of Kanwar lake , Source – https://www.facebook.com/

What are oxbow lakes?

Oxbow lakes are crescent-like water bodies formed due to erosion and deposition in meanders of rivers. Meanders are loops or curved structures formed in the course of a river (as in figure 1) due to friction or tectonic activity. The speed of water flow in the outer section of this meander is more than the inner part causing its neck to become narrower over time. Eventually, the size of this loop increases making it harder for the river to flow through it so it opts for a straight path. Finally the ends of this meandered loop are separated by deposition of sediments or silt separating the river and a horseshoe-like structure called oxbow lake.

Biodiversity:

The Kanwar oxbow lake also houses the eminent Kanwar bird sanctuary which is one of the largest breeding grounds for migratory birds in India. From critically endangered to vulnerable, you can find over 100 species of birds during the peak season. The oriental white-backed vulture and greater adjutant are some of the rare species found.

Degradation of the water body:

A study conducted by Ashok Ghosh, scientist and chairman of the Bihar State Pollution Control Board, found that the lake covered 6,786 hectares in 1984 but reduced to a mere 2032 hectares by 2012. Illegal poaching, deforestation, land encroachment, and overgrazing have destroyed the lake’s natural ecosystem. The constant discharge of chemical effluents into the water body has made the water turbid and acidic, further harming the aquatic life.

Another concern is the lack of accountability by authorities. Even Though the lake is protected under the Wildlife Protection Act of 1972, no serious measures have been taken to preserve it. The district authorities have taken no action against the buying and selling of land designated to the wetland and illegal agriculture around it. Furthermore, land disputes between the local farmers and tribes have elevated the tension there.

A strong legal framework and co-operation from the locals is necessary for protecting this water body and the rare species that depend on it. Locals have to be educated and awareness has to be spread while the government must develop a coherent program to initiate conservation.

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