River systems

 

River systems 

Keerthana

27/08/20

Theme:change

Honestly, at first I just thought that the river system was just the ecosystem and the environment around the river but it turned out to be so much more. A river system was actually the entire natural water system in a drainage basin. I’ll kick start this intriguing system from the basics, like what a river is. Well, a river is a large natural streams of water that is channeled and then empties out in a large body of water like a sea or a lake. Since, I have already mentioned what a river system is, I will immediately jump to what a river profile is, in simple words it is a line representing from where the river starts to its mouth, where it meets the sea. 

The point where the river starts from is called as the source or the origin of the river and where it meets the sea is called as the mouth. The first stage of the river or the upper course of the river or also the young phase, here the potential energy of the water becomes kinetic and flows at a high velocity because the gradient is very sharp ( but I am not complaining cause white water rafting is probably one of the best thrills out there).The river bed is narrow but deep and this leads to the eroding of the rock. Then you might ask, what is erosion? Well, it is the gradual destruction of something by a force and in this case, the force is the kinetic energy possessed by the fast moving water and the ‘something’ would be the bedrock or the sides of the river. So, vertical erosion is the main process that happens here. Since, the kinetic energy is so high here, it makes it ideal to build a dam for the production of hydroelectricity. Waterfalls and Tributaries are also quite an important characteristic here but I wont emphasize on it much in this blog.

 The next stage is the middle course or the matured phase, here the gradient is comparatively dull to the upper course and because of this the kinetic energy has also decreased. If you connect the dots, then because of the less kinetic energy or the less force cutting through rocks, that means that the erosion will also be less than that compared to the upper course of the river where erosion was happening predominately. Then, which process is known in the middle course would be the immediate question risen and if you think about it this way, the water still has kinetic energy so obviously there is still some Lateral erosion happening and also you aren’t exactly towards the end of the river, so major deposition cant happen just yet. Kinetic energy doesn’t help in eroding rocks but also transporting the eroded material, the load, so the main process here is transportation of the sediments. Also, how can I forget this, in the middle course the river is more wider because the volume of the water that is sent plummeting down from the upper course is a lot, and I am in no way joking about the volume. Ox bow lakes, meanders and horseshoe lakes are also a common landscape characteristic found in this stage of the river.

 The last stage of the river is called the lower course and also the old stage ( though the entire river is the same age, quite ironic and contradictory might I say). Here, the gradient is almost close to zero and that is why the water has very less kinetic energy which means that erosion for sure is also almost close to zero percent and the transportation also cant happen as well as it did in the middle course. What other process is perfect under these condition other than deposition, finally the river can take a rest and give a rest to the poor land that has been eroding throughout the upper and middle course. This is how alluvial plains, deltas and meanders ( meanders are also present in the middle course cause minor deposition dies take place) are created, because of the deposition. It creates fertile lands that are suitable for agriculture, changes the path of rivers ( cant blame the rivers for wanting to explore new places, can we). Distributaries is also an important characteristic but I will not also be talking about this in detail at the moment.

I believe that we can come to a conclusion that force, gradient and the erosion cycle ( erosion, transportation and deposition, all of these together is known as the erosion cycle), are all interconnected and affect one and another. These processes create and change landscapes for the better or for the worse.

In the next blog, I’ll be speaking about coastal system, so I hope for now, this blog was able to intrigue your interests and curiosity was raised about the phenomenon.