rivers - river processes

Description

GCSE Geography Mind Map on rivers - river processes, created by Gabriel Keen on 05/01/2018.
Gabriel Keen
Mind Map by Gabriel Keen, updated more than 1 year ago
Gabriel Keen
Created by Gabriel Keen about 8 years ago
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Resource summary

rivers - river processes
  1. erosion
    1. the process by which a river wears away at the land.
      1. the ability for a river to erode depends on its velocity
      2. lateral erosion
        1. starts to occur in the middle course and prominent in the lower course
        2. vertical erosion
          1. occurs in the upper course
          2. types of erosion:
            1. hydraulic action
                1. sorry this is at the coast but it's the same principal
                2. the force of a river against the banks can cause air to be trapped in cracks and crevices. the pressure weakens the banks and gradually wears it away
                3. attrition
                    1. stones that have just entered the river are large and jagged. As transportation occurs the stones collide with each other and knock off each others jagged sides making them smaller and more spherical. The further they travel the more this occurs.
                    2. abraision
                        1. sometimes called corrasion
                          1. small load scratch and scrape their way down a river during transport, this wears down the banks and bed of the river channel
                          2. solution
                              1. also called corrosion
                                1. the dissolving of rocks such as limestone or chalk
                                  1. this could be the load itself
                            1. transportation
                              1. the process by which a river carries its load.
                                1. load is anything carried by a river
                                  1. all shapes and sizes
                                    1. all different materials
                                      1. rocks fallen ito the river or the river banks and bed that have been eroded
                                    2. types of transportation:
                                      1. traction
                                          1. large or heavy load is rolled along the river bed
                                            1. not necessarily heavy load, it could be that the rivers velocity is not big enough
                                              1. load carried in this way is called bedload
                                            2. saltation
                                                1. Small pebbles and stones are bounced along the river bed. When velocity increases they are picked up, when it decreases they are deposited.
                                                2. suspension
                                                  1. fine light material such as alluvium is held up and carried within the rivers flow
                                                    1. this is called suspended load
                                                    2. solution

                                                      Annotations:

                                                      • yes, again
                                                        1. minerals are dissolved in the water
                                                          1. this is a chemical change to rocks such as limestone and chalk
                                                            1. load carried in this way is called solute load
                                                      1. deposition
                                                        1. the bigger the load particle the more velocity is needed to keep it moving.
                                                          1. when velocity falls, big boulders are therefore the first to be deposited
                                                            1. this explains why mountain streams have boulders along their bed while there is only fine silt near the mouth
                                                          2. the river will deposit more load when there is a period of draught and the discharge is low
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