Features Formed by River Erosion
A meander is merely one in a vast list of typical meandering bends, turns, or curves that can be found along a river channel or a stream. They are typical in rivers that run through floodplains because the speed of the water impacts the banks, internally eroding them and depositing sediments on the opposite side. When a river or stream flows along its floodplain or, occasionally, shifts within a river valley, it strikes the banks from side to side. It is created when the river erodes the sediments on the riverbank’s outer concave and deposits the eroded materials and other leftovers on the inner convex of the bank, also known as the point, further downstream or down the river. As the river channel moves back and forth transversely down the valley axis of the floodplain, continuous erosion of the concave side of the river and deposition on the convex side of the river results in the formation of a sinuous course. The meander belt is the location where the meandering stream regularly modifies its course throughout the valley or flood plain. The average width of the river channel is roughly 15–18 times wider than the meander belt. Over time, meanders in a river’s course could cause issues with the roads over bridges.
An oxbow lake has a U-shaped shape. A lake develops when a river is severed from the main stream. It is a byproduct of the way the river meanders. It happens when the river forgoes a previous meander and chooses a quicker path across its course (Bogoni, Lanzoni, & Putti, 2017). It typically appears on plains near where rivers discharge their water, particularly in flat areas. The creation of oxbow lakes is facilitated by the large meanders that occur in the plains, which frequently include two bends. The first curves away from the river course, while the second curves back toward it. On the convex side of the meander, there is constant erosion of the sides that curve outward, i.e., the concave side, with corresponding bluff deposition. The river finally connects the two curves, taking on a new straight course, as a result of continual erosion, deposition of silt, and bluff formation (Bogoni, Lanzoni, & Putti, 2017). The zone between the river flow and the earlier meander is then further blocked by deposition. An oxbow lake is created when the meander is fully closed off and cut off from the river. Oxbow lakes frequently transform into bogs or swamps as they stale out over time. Due to the lack of a water source, the water they hold may evaporate during the dry season, depleting the lake and leading to the formation of a swamp.
The feature known as a point bar is created when eroded materials are deposited. It develops when alluvial soil that has been eroded from the river course is deposited on a river bend that is close to a slip-off slope.
They are frequent occurrences in floodplains with meanders when the river has lost its erosive strength and deposition has begun there as a result of the low water velocity. The majority of them are found on the inside side of a river stream bend and are always crescent-shaped. They are primarily composed of sediments and other materials that the river carried to the floodplains as it flowed by. They are frequently flooded by water when the water level rises due to their low laying capacity and constant elevation close to the water’s surface. Due to their elevation above the water’s surface, they do make excellent resting spots for boats.
M. Bogoni, S. Lanzoni, and M. Putti Can the migration history affect the future morphology of the river? Meander morphodynamics over self-formed floodplains. in Abstracts of the AGU Fall Meeting.