EROSION consists of three components, which are Corrasion, Hydraulic Action and Solution.
Any surplus energy is used by a river to carry out erosion. Erosion is the picking up and removal of material. There are three main processes by which a river will erode its channel.
Any surplus energy is used by a river to carry out erosion. Erosion is the picking up and removal of material. There are three main processes by which a river will erode its channel.
Solution: water contains dissolved carbon dioxide from the air and this may react with limestone and chalk, causing it to dissolve.
Corrasion: this is where particles of rock carried by the river grind away at the bank and bed. It
is the most significant type of erosion in most rivers.
Hydraulic action: this is the sheer power of the water as it crashes onto the bed or against the banks. It is particularly significant at waterfalls and raids or during times of flood. Air bubbles may burst in areas of great turbulence sending our shockwaves which may increase erosion. This is cavitation.
DECOMPOSITION occurs throughout the course of a river wherever the speed of flow drops such that particles can no longer be carried. This could occur on the inside bend of a meander on the bed of the ricer or close to its banks where friction is at its greatest or where the ricer enters the sea or a lake and its flow is checked.
In addition, erosion mainly happened at upper course and middle course of a river, where holds the largest energy, and also the fastest speed. Decomposition mainly happened at the lower course of a river, where has the lowest speed or energy, even though its volume may be the largest.
Done by Fangwei
i think the method to remember the different types of erosion is quite useful. the CASH method, where C represents corrasion, A for attrition, S for solution and H for hydraulic action.
ReplyDeletejia min jh406
hey!just an addition to your post!(:
ReplyDeleteFor hydraulic action，when there is the presence of joints or cracks in rocks or in river banks, water will bombard the joints or cracks and hydraulic action will cause it to increase in size. this is particularly significant in rapids and waterfalls.
also, attrition is also a erosion process.
it is when rocks rub and hit on each other. the rocks turn from a rough and hugge surface area rock into a small and smooth rock. therefore pebbles or rocks seen in the lower or middle course are usually smooth and smaller(:
JIAYI!