geography rivers

physical landscapes

what is hydraulic action

the sheer force of the water hitting the bed and banks. this is most effective when the water is moving faster and there is a lot (velocity and volume) of it

what is attrition

when the stones and boulders carried by the river knock against eachother and over time are weakened, causing bits to fall off and reduce in size

what is abrasion

when the bedlam the river is carrying repeatedly collides with the river bed and banks to break off some material. sandpaper effect

what is solution

occurs only when the river flows on certain types of rock such as chalk and limestone as they are soluble in rainwater and become part of the water they are dissolved by it.

how is an oxbow lake formed

1) as it enters the middle course, wider and deeper = more volume and efficiency= surplus energy and increased lateral erosion

2) energy is directed sideways to the bank so river starts to bend and water travels faster to cover a large stance

3) thalweg directed to out bend = more velocity, erosions by hydraulic action and abrasion so decrease meander neck

channel will take more efficient route and break meander neck, oxbow lake left where old meander bend existed and dry out due to no flow = meander sear.

how is a meander formed

1) due to its helical flow = channel wide and deeper = more volume and efficiency

2)