The Journey along Ganges River

Tuesday, March 10, 2009

Lower Course of the River - Floodplains and Levées

This is the view of the middle course and also the upper course of the view:

Beautiful.. isn't it?

At the lower course of the river:
-gradient is gentle
-river channel is wider than middle course
-volume of water flowing increases as more tributaries joined the river

Know what I saw? People living on the floodplains! From the term floodplains we could see that flood occurs frequently there. I learned a lesson from the villagers about how floodplains and levees are formed:
-As the river continues its journey towards the sea, the valley cross section continues to become wider and flatter with an extensive floodplain either side of the channel. -The river erodes laterally and deposition also becomes important.
-The time it reaches the lower course the river is wider and deeper and may contain a large amount of suspended sediment.
-When the river floods over the surrounding land it loses energy and deposition of its suspended load occurs.
-Regular flooding results in the building up of layers of nutrient rich alluvium which forms a flat and fertile floodplain.
Interesting right?
Here's a picture of a floodplain I took:

A network of converging and diverging streams separated from each other by narrow strips of sand and gravel.
A picture of the braided stream I took

I've learnt another lesson from the villagers:
Here are the conditions of the formation of a braided stream:

* an abundant supply of sediment
* high stream gradient
* rapid and frequent variations in water discharge
* erodible banks

Nature is so amazing~!


Where two streams (or rivers) join, the smaller one is called the tributary. The place where the two streams join is called the confluence.


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