A meander is just one of the series of common winding bends, turns or curves along the river channel or along a stream. They are common in rivers flowing through a floodplain as the velocity of the water hits the banks, eroding it internally and depositing the sediments on the other side. It is formed when the river or stream hits the banks from side to side as it flows along its floodplain or sometimes shifts within a river valley (Bogoni, Lanzoni, & Putti, 2017). It is produced as the river erodes the sediments on the outer concave along the riverbank and deposits the eroded materials and other residues downstream or down the river on the inner convex of the bank, also known as the point bar.
Continuous erosion of the concave side of the river and deposition on the convex side of the river leads to the formation of a sinuous course as the river channel moves back and forth transversely down the valley axis of the floodplain. The point at which the meandering stream changes its channel across the valley or floodplain continuously is the meander belt. The meander belt ranges approximately between 15-18 times the average widths of the river channel. Through time, meanders may move down the river stream leading to problems in the roads across bridges.
An oxbow lake is a kind of U-shaped Lake formed as a result of a river being cut off from the mainstream. It is a resultant feature of the river meander. It results when the river abandons an earlier meander and finds a shorter way through its course (Bogoni, Lanzoni, & Putti, 2017). It usually forms in flat areas, mostly in the plains close to where the river drains its water. Large meanders are formed in the plains, and they often have two curves that lead to the formation of an oxbow lake. One curves away from the river course, and the other curves back to the course. Continuous erosion of the sides that curve outwards, that is, the concave side with respective deposition of the bluffs, occurs on the convex side of the meander. Continuous erosion and deposition of silt and bluffs eventually lead to the river connecting the two curves, making it have a new straight course (Bogoni, Lanzoni, & Putti, 2017). Deposition then continues to block the region between the river course and the older meander. When the meander is completely blocked and separated from the river, it forms an oxbow lake.
Oxbow lakes often turn to swamps or bogs since they dry up with time. Given that they do not have a water source, the water they contain may end up evaporating during the dry season, leaving the lake with no water, hence the formation of a swamp.
A point bar is a feature formed as a result of the deposition of eroded materials. It is formed when the alluvial soil eroded from the river course gets deposited on a bend of a river just below a slip-off slope. They are common features in floodplains with meanders where the river has lost its erosive power, and due to the low water velocity, it starts deposition in these areas. They are always crescent shaped and most of them are located on the inner side of a river stream bend. They are mainly made up of sediments and materials carried by the river as it flows along the floodplains (Bogoni, Lanzoni, & Putti, 2017). They are always elevated close to the levels of the water, and because of their low laying capacity, they are at times flooded by water when the volume of water increases. They do form very good resting points for boats because of their elevation on the water level.
Work Cited
Bogoni, M., Lanzoni, S., & Putti, M. (2017, December). Meander morphodynamics over self-formed floodplains: can the migration history affect the future morphology of the river?. In AGU Fall Meeting Abstracts.
