Rivers 4.0 / 5 based on 2 ratings ? GeographyWater and riversGCSEWJEC Created by: katieCreated on: 04-04-13 14:48 Hydraulic Action The force of the water on the bed and banks of the river. It is particularly powerful when the river is in flood. The force of the water wears material away from the bed and banks of the river. 1 of 9 Abrasion The river carries particles of sand and silt. It moves pebbles and boulders at times of high flow. The material rubs against the bed and banks of the river and wears them away. Also called corrasion. 2 of 9 Solution Some rock minerals, such as calcium carbonate (in limestone and chalk) slowly dissolve in river water, which is sometimes slightly acidic. Also called corrosion. 3 of 9 Attrition The load being carried by the river collides and rubs against itself, breaking up into smaller pieces. The rough edges become smooth, forming smaller, more rounded material. Eventually the particles are reduced to sand and silt sized particles. 4 of 9 Traction Boulders and pebbles are rolled along the river bed at times of high discharge. This requires the most energy because the boulders are heavy so a lot of energy is needed to push them along the river bed. 5 of 9 Saltation Sand sized particles are bounced along the river bed by the flow of water. 6 of 9 Solution Some minerals, such as calcium carbonate, dissolve in water. This requires very little energy. 7 of 9 Suspension Fine clay and sand particles are carried along within the water, even at times of low discharge. 8 of 9 Deposition This is when a river drops its load. It could be because: There is a smaller volume of water - not enough energy to carry the load The river is shallower There is more friction so the river slows down and less energy There is a bend/meander in the river It slows down on the inside bend and it is shallower There is human activity, e.g. a dam There is a lot of depostition behind the dam Input of sediment There is too much sediment so it is too heavy to carry, e.g. a landslide 9 of 9
Comments
No comments have yet been made