Transportation in River Channels

HELLO!! EVERYONE.
I will be blog on one kind of river channel processes--Transportation.

Rivers have energy. (As a reminder, rivers' energy come from two sources--kinetic energy as well as potentional energy. Thus the factors affect the energy of a river are, just to name a few: gradient of land, roughness of channel, shape of channel cross-section, volume of river...etc) After successfully overcoming friction, energy is used to carry or transport eroded materials such as mud, sand, boulders and dissolved materials. These materials are called its load. River transport their load by four processes. These processes are traction, saltation, suspension and solution.

Traction: larger particles like pebbles and boulders roll and slide along the river bed. They move only if the speed of the river is great enough to move them. Some of them are so heavy that they can only be rolled along during heavy flooding.

Saltation: large particles such as gravel and coarse sand are lifted and dropped along the river, so they bounce along the river bed in a series of bed.

Together, the saltation load and the traction load form the bedload.

Suspension: fine particles such as clay, silt and fine sand are carried along without contact with the river bed. Materials carried in suspension(suspension load) usually forms the greatest part of the total river load and this exlains why most rivers look muddy.

Solution: soluble minerals(dissolved load) in the rocks such as salts of calcium and sodium are carried away in solution . Trying to look out for these type of load in a river? Too bad, they cannot be seen by a naked eye. Solution occurs even when the speed of the river and its volume of water are low.

Yup:) So that's all about trasportation. If you are unsatisfied, or still get something unclear, ahha, then maybe you would like to watch this short yet cute video about river transportation:
http://www.youtube.com/watch?v=IhWrn6ys1Wc

IS2104 is over, yet I think (Physical) Geography should not end here. Geography is both useful and interesting. USA's 35th president Joh F. Kennedy said" Geography has made us neighbours." And believe it or not(don't believe it), famous scientist Albert Einstein said:""As a young man, my fondest dream was to become a geographer. However, while working in the customs office I thought deeply about the matter and concluded it was too difficult a subject. With some reluctance I then turned to physics as a substitute."-----Actually this is a blunder, to find out more, visit this http://geography.about.com/od/geographyglossarye/g/ggeinstein.htm

I think (Physical) Geography is not about maps, nor about memorisation of facts. The learning of Geography to a certain extent is about learing our home--the Earth.


Done by Cao Li :) JH406(13)