The Lower Course~
POSTED BY DYLAN TING 04MAR 2011 2.00PM
Wheeeee.. We're finally at the lower course of the river.
You know...Honestly, as much as we enjoy this trip, sometimes we feel too tired to continue. It has been tough controlling how we kayak down the middle course with the velocity of river water gushing down so quickly.
Anyway, we are finally at the lower course in which water begins to flow slower. This is also because the gradient of the river has become less steep. The shape of the valley in a lower course is usually the widest and u-shaped.
You know...Honestly, as much as we enjoy this trip, sometimes we feel too tired to continue. It has been tough controlling how we kayak down the middle course with the velocity of river water gushing down so quickly.
Anyway, we are finally at the lower course in which water begins to flow slower. This is also because the gradient of the river has become less steep. The shape of the valley in a lower course is usually the widest and u-shaped.
Flood plains
Along the lower course, flood plains is quite a common sight. Floodplains are wide, low-lying,level plains filled with
sand,silt and clay which are deposited along the river banks during times of flood. Recall that the speed of flowing water is slower in the lower course. As such, less erosion occurs and more deposition takes place; this causes the formation of floodplains.
Another reason for the formation of floodplains can be due to rain. During times of heavy rain, the water level rises and the mean speed of water flow increases. This causes any deposited material along the lower course to be suspended in the river water. As rain increases the volume of water in the river, the river water soon overflows its banks.
Due to the large wetted perimeter, water at the surrounding area would encounter more friction, hence slowing down the velocity of the river water that has overflowed the banks. This leads to the occurrence of the deposition of sediments.
The deposition would form alluvium, which consists of sand, silt, clay, and fine particles. Coarser materials would be deposited nearer to the banks, while finer particles which are deposited further away. As more alluvium continues to build up, a layer of alluvium will form along the banks of the river. This is called a flood plain.
Another reason for the formation of floodplains can be due to rain. During times of heavy rain, the water level rises and the mean speed of water flow increases. This causes any deposited material along the lower course to be suspended in the river water. As rain increases the volume of water in the river, the river water soon overflows its banks.
Due to the large wetted perimeter, water at the surrounding area would encounter more friction, hence slowing down the velocity of the river water that has overflowed the banks. This leads to the occurrence of the deposition of sediments.
The deposition would form alluvium, which consists of sand, silt, clay, and fine particles. Coarser materials would be deposited nearer to the banks, while finer particles which are deposited further away. As more alluvium continues to build up, a layer of alluvium will form along the banks of the river. This is called a flood plain.
POSTED BY Justin Chan 04MAR 2011 2.38PM
Levees
Today, we are going to share with you about levees!
Levee is one of the most interesting features of rivers. In fact, we humans have started adopting a similar idea of levees and implemented it around the world as a way to regulate the water level at rivers or coastal areas.
Before much talk about it, let us first show you a picture of a levee.
Levee is one of the most interesting features of rivers. In fact, we humans have started adopting a similar idea of levees and implemented it around the world as a way to regulate the water level at rivers or coastal areas.
Before much talk about it, let us first show you a picture of a levee.
As you can see from the figure above, levees look like slopes along the banks of the river. These levees are usually formed due to the periodic flooding; as these floods continue, continual depositing of coarser materials form raised embankments known as levees.
Sometimes, levees and the river beds become higher than the floodplain. That is dangerous and may lead to disastrous consequences when a flood occur.
Sometimes, levees and the river beds become higher than the floodplain. That is dangerous and may lead to disastrous consequences when a flood occur.
POSTED BY DYLAN TING 05MAR 2011 4.56PM
Delta
Whoooo! What a wonderful sight! We have finally reached the Ganges river delta. Here's a picture of a delta!
Deltas look really nice! As the gradient at the lower course decreases, the velocity of the river water slows down a lot when approaching the mouth of the river. Through deposition, the sediments will be deposited at the mouth of the river. Continual deposition over a period of time will build up a platform of alluvium.
After some time, a platform of alluvium forms. It continues to form until it rises above the sea level. This platform is called a delta.
Once that happens, vegetation grows on the delta. This stabilizes the delta. Further deposition continues to extend the delta and the course of the river in to the sea.
After some time, a platform of alluvium forms. It continues to form until it rises above the sea level. This platform is called a delta.
Once that happens, vegetation grows on the delta. This stabilizes the delta. Further deposition continues to extend the delta and the course of the river in to the sea.
Wow... Time flies. It seemed just like a while back when we started from the upper course of the Ganges river, and now we are at the mouth of the Ganges river. We hope that just as we had fun traveling down the Ganges river and blogging all about what we see along the way, you had fun too. It truly is an awesome trip down the river and you should come and experience it soon one day.
Till then!
Have fun!
Till then!
Have fun!
Head back to the Middle course
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