A river is a large natural stream of water that flows to other large bodies of water. The river is used for navigation, drawing electricity, for fields and other daily purposes. But the flow of a river is irregular. This makes it difficult for navigational purposes. Severe rainfall and other climatic changes can cause the river to flood. Fields and even lives are at cost. To reduce floods and make the river more navigational techniques like river straightening have been used.
River straightening is a process in channelization where the bends, curves and other obstacles in a river’s path are removed. Hydro-modification or river engineering aids in doing this. There are many benefits by straightening rivers.
The removal of curves and obstruction makes the movement of water more swifter making navigation much easier.
The flow of water increases and it moves rapidly downstream which reduces the occurrence of floods upstream to a large extent.
Erosion levels are reduced due to the removal of large number of curves in a river.
There are lots of agricultural lands that are often flooded by rivers. By straightening the water can be restricted to those lands which allow the growth of vegetation.
Though river straightening has some benefits there are many disadvantages to this process. There are adverse effects on the natural environment.
It has disrupted the river’s ecosystem. Aquatic life forms and vegetation have been decreasing. These life forms require a specific temperature and speed of water flow to survive. But the modification of rivers has increased the temperature of water. The velocity of water has increased making it difficult for the survival of aquatic life. Pool rifle patterns have been eliminated and substrates keep shifting.
Vegetation along the riverbanks has been removed. This reduces the food for the aquatic life forms. It also reduces the natural shade, increasing the temperature of the water. The water banks have become unstable and the sedimentation level in the water has increased.
The velocity of the water flow has increased because of straightening. The flow of water to the downstream has resulted in flooding of downstream areas. The banks have been pulled into the river because of the velocity of the water and this leads to erosion. The channels have deepened and widened.
The losses of wetlands have increased thus resulting in the loss of habitat for many life forms.
Recreational uses of streams have been reduced.
Because of all the effects on the environment many rivers that have been straightened are in the process of being restored to its original shape and form. With modern technology and advances mankind has the ability to even change the natural course of nature. By doing so there are many advantages and disadvantages. Things should be done in a way where the environment is not affected or disturbed.
References
http://www.encyclopedia.com/doc/1O112-riverchannelization.html
Encyclopedia of Water Science
http://en.wikipedia.org/wiki/River_engineering
