how does water erode the banks of a river?

Question

please be specific

Answer 1

There are a lot of factors that effect stream erosion. It's actually a pretty interesting subject if you like spending a lot of time in, on or around rivers, or you dig physics!
At the most basic level, water flow creates friction against the sides and bottom of the stream causing rocks and minerals to displace and/or dissolve. The rate and amount of erosion that takes place is dependent on factors like stream flow (volume and speed of water) and geological makeup of the stream bed ( limestone will erode much more slowly than sand ), geography, (slope of the landscape, gravity) and last but not least, fluid dynamics.
Flowing water that comes into contact with the stream bed is slowed down because of friction. This means that the water flowing in the middle of a stream is moving faster relative to the water at the bottom and sides of the stream. As a result a current results that is not uniform or "flat" , but rather a helical or " corkscrew " current as it proceeds downstream. In sand or in soft terrain, the result of this helical flow is easy to see as it creates the windy, meandering pattern of the river channel.
As time passes, the river undercuts outside banks where centrifugal force is strongest, and deposits sediment on the inside banks where centrifugal force associated with the helical flow of the water in the stream is weakest.
Anybody who has canoed or kayaked on a river will have experienced the different surface water speeds.
Flooding, which in most rivers and streams is cyclical, is another significant factor in the role water plays in erosion. For example, in northern areas where rivers freeze, there is normally some type of spring flooding. Depending on snow cover, speed of thaw, ice jamming etc, the thaw can be slow and orderly, or, catastrophic - scouring the banks or changing the entire course of the river. In either case, the increased volume of water will effect the rate of erosion.

Answer 2

Water flowing slowly takes grains of rock and sediment downstream and toward the major water source (lake, ocean). Rocks along the banks are eroded and turned to sand and the sand is slowly swept down the banks. This is a very slow process taking hundreds if not thousand of years in many cases.

Answer 3

Yes, the water takes the sediment into the ocean. However, most banks will have plants that help hold onto some of it so that it doesn't erode. Erosion occurs when these plants are no longer there or are few. Invasive animals could eat the plants; humans could dig them up to create canals; storms can destroy them; etc.

Answer 4

In maximum places, the river mattress is yours. purely like that land constantly became, in the previous the river moved. yet no longer the water interior the river. you may no longer dam it, or do something that would desire to intervene with boating on the river. You *would desire to*, with the suited helps, be allowed to restoration the river to the banks it had in the previous the erosion. or you may desire to no longer.

Answer 5

The water is moving and its slowly taking grains of sand along the banks with it.