Formation and Importance of Oxbow Lakes in East Champaran
Oxbow lakes begin their formation as meandering paths. When a river finds an alternative route away from its floodplain, such lakes are created. Typically, these lakes form in flat plains where rivers converge into another water body. In these plain areas, rivers often have wide, winding paths. The meandering paths that create oxbow lakes consist of two types of bends: one that turns away from the river’s direct path and another that curves back. The concave edge of the closest bends is called the “concave bank.” The force of the flowing river deposits sediments along these concave banks. In contrast, the opposite banks are known as “convex banks,” where erosion occurs. Sediments and debris accumulate on the convex banks, a process known as deposition. Due to erosion and deposition, a new channel eventually cuts through a narrow strip of land, allowing the river to create a shortcut.
Oxbow lakes are characterized by still water, meaning that water does not flow in or out of them. These lakes are ecologically significant as they provide habitats for diverse flora and fauna, enhance sediment storage, and contribute to groundwater recharge. The availability of surface water increases irrigation potential. These lakes serve as critical habitats for various aquatic and terrestrial species, including fish, waterfowl, amphibians, reptiles, and other wildlife. They also act as refuges for wildlife during flooding events, storing floodwaters and thereby mitigating the impacts of floods. Additionally, these lakes can function as carbon sinks.
In the Motihari block of East Champaran, several such structures exist. There are five lakes in the block, partially located in urban areas and rural surroundings. The combined area of these six lakes is 567 hectares, with a water storage capacity exceeding 1000 Ha.M, which will play a crucial role in meeting future water needs. Unlike other lakes, these can be replenished due to the nearby river connection. However, the risk of encroachment on these lakes has increased due to declining water levels.
The Budhi Gandak River has a drainage line that flows for 12 kilometers in the Tikuliya Panchayat before rejoining the Budhi Gandak River. This drainage line is known as the Imarti River. The lakes within the block are directly or indirectly connected to the Imarti River. The Imarti River is linked to the Budhi Gandak River through two sluice gates. Locals, considering the flood history, wish to use these gates solely for the disposal of excess rainwater. Both the beginning and end of the Imarti are associated with these sluice gates. Over the past four years, due to reduced rainfall and the absence of floods, there has been a significant decrease in water levels in these structures.
The district administration is making efforts to rejuvenate these lakes. Recently, a survey of these lakes and the Imarti River was conducted by technically skilled officials from the Rural Development Department. The local community has also developed an understanding of their utility and is eagerly awaiting the revitalization of these lakes. If successful, the irrigation capacity of the area could increase by 1500 hectares, benefiting approximately 500 families through fish farming, reducing the impacts of floods, and preventing encroachment on the lakes.
