by Ms Manu

Created on: August 05, 2009   Last Updated: August 13, 2009

The Harappa civilization flourished on the banks of the river Indus and the Egyptian on the banks of the river Nile. Similarly the civilizations of China, Incas, Mayans and many more, all existed on the banks of the river or a large water body. Even in modern day we see that most of the big cities are located on the banks of rivers, lakes or sea. This tells the undisputable important role water plays in the life of man, necessary for sheer existence and required for socio economic life.

Since the dawn of civilization man has tried to modify the water sources to suit his needs, what started as digging small wells and canals for irrigation, today has grown to be a huge branch of engineering, called 'River Engineering'. River engineering is the process of planned human intervention in the course, characteristics or flow of a river with the intention of producing some defined benefit. River engineering encompasses many activities like building dams, straightening of the rivers, building canals, leaves and bunds, reversing the flow of rivers, altering the depth and width of the rivers etc. The most commonly seen product of river engineering are dams, and common though less heard river engineering feat is river straightening, the words are self explanatory, river straightening is a process of straightening the path of the river to reduce its curves and bends. The river does change its path, but over a period of time slowly and gradually flowing along the path of least resistance, and also allowing its associated ecosystem to evolve along with it.

To understand the how and why of river straightening, let's study a hypothetical river ecosystem. The components of this ecosystem are the man living on the bank of the river, fish in the river, plants on the river bank, birds and other small animals living on the river bank. Let us get a snapshot of the ecosystem of the river before and after river straightening and then study them.

Before the river straightening:

The river meandered across plains and flowed to the sea, carrying sediments and debris and depositing them in its path. The debris like logs of trees, small boulders trapped more debris forming mini dams and extending the bank into the river, constantly adding to and eroding the river banks. The sediments deposited on the river bed and the moist rocks were a thriving home for algae, the main source of food for the fish. The river plains along the river bank being rich in sediments deposited by floods every

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