Paper 1: River Landscapes Flashcards
Hydraulic action
the force of water crashing against the river bed or banks causing material to be dislodged and carried away by the river.
Abrasion
rocks are thrown against the river bed/banks causing more material to be broken off and carried away by the river.
Attrition
rocks are thrown against each other by the river which results in the rocks becoming smaller and rounder
Solution
river water dissolves certain types of rock
Traction
large boulders are rolled across the river bed.
Saltation
Saltation - small pebbles are bounced along the river bed.
Suspension
Suspension - fine light material is carried along in the water.
Solution
minerals are dissolved in the water and carried along in solution.
Why does a river deposit its load?
it no longer has enough energy to transport it anymore.
Load transport in upper course
-Traction is most common
- large boulders have not yet undergone attrition
-can only be rolled
Load transport in lower course
-Suspension is most common
- load is more fine, due to attrition,
-so it floats within the water.
Relief of river in upper course
-very steep
- surrounded by mountainous terrain.
Relief of river in lower course
- flatter
- surrounded by lower-lying hilly valleys.
Cross profile of a river in the upper course
- very narrow
- shallow river channel
- surrounded by v-shaped steep valleys.
-There is little discharge - very little velocity of water
Cross profile of river in the lower course
-the discharge increases,
-the width and depth of the channel increases
- the surrounding valley becomes u-shaped instead.
erosion in middle/lower course
-lateral erosion
-widens channel
causes of flooding
-SRO
-deforestation
-steep relief
-urbanisation
Surface runoff
-water flowing over surface
infiltration
water sinking into soil from grounds surface
soil moisture
water held in soil layer
through flow
-water flowing through soil layer parallel to surface
groundwater flow
-water flowing through rock layer
percolation
water sinking through soil into rocks below