Geography Braiding Notes
Braiding:
Braiding occurs when the river is forced to split into several channels separated by islands called braid bars or eyots because there is too much sediment in the river, deposition happens very quickly and water is still to get through.
As water levels fall and energy decreases, the rapid deposition of the coarsest load begins to block the main channel. As the main river channel is no longer competent to move the material blocking its path, it may subdivide into a series of smaller diverging and converging channels that seek to find the easiest route past the obstructing sediment.
It is a feature of rivers that are supplied with large loads of sand and gravel. It is most likely to occur when a river has variable discharges. The banks formed from sand and gravel are generally unstable and easily eroded. As a consequence, the channel becomes very wide in relation to its depth. The river can become choked, with several sandbars and channels that are constantly changing their locations.
Braiding also occurs in environments in which there are rapidly fluctuating discharges:
Semi-arid areas of low relief that receive rivers from mountainous areas. Where rapid evaporation and infiltration of water reduces the volume, velocity and therefore the competence of the stream.
Glacial stream with variable annual discharge – Alpine snowmelt or arctic areas. In spring, meltwater causes river discharge and competence to increase; therefore the river can transport more particles – they carry a very high load in relation to their capacity. As the temperature drops and the river level falls rapidly, competency and capacity are reduced, the load is deposited as islands of deposition in the channel.
Braiding occurs when the river is forced to split into several channels separated by islands called braid bars or eyots because there is too much sediment in the river, deposition happens very quickly and water is still to get through.
As water levels fall and energy decreases, the rapid deposition of the coarsest load begins to block the main channel. As the main river channel is no longer competent to move the material blocking its path, it may subdivide into a series of smaller diverging and converging channels that seek to find the easiest route past the obstructing sediment.
It is a feature of rivers that are supplied with large loads of sand and gravel. It is most likely to occur when a river has variable discharges. The banks formed from sand and gravel are generally unstable and easily eroded. As a consequence, the channel becomes very wide in relation to its depth. The river can become choked, with several sandbars and channels that are constantly changing their locations.
Braiding also occurs in environments in which there are rapidly fluctuating discharges:
Semi-arid areas of low relief that receive rivers from mountainous areas. Where rapid evaporation and infiltration of water reduces the volume, velocity and therefore the competence of the stream.
Glacial stream with variable annual discharge – Alpine snowmelt or arctic areas. In spring, meltwater causes river discharge and competence to increase; therefore the river can transport more particles – they carry a very high load in relation to their capacity. As the temperature drops and the river level falls rapidly, competency and capacity are reduced, the load is deposited as islands of deposition in the channel.