by Adelani Aderemi

Created on: July 21, 2009   Last Updated: August 01, 2009

It is very uncommon to see naturally straight rivers because water flows through a path of least resistance. Thus rivers meander round obstacles until they empty into another river, lake or ocean. For many reasons, human beings have devised means of straightening water courses. Straightening, in simple terms involve moving of mud and sand along a river course until the bends of the river are filled and its main channel are excavated sufficiently enough to contain the volume of water.

Navigation and building of dams are major among the reasons river courses are straightened and dredged. However, the economic benefits of these projects must not divert attention from the ecological and socio-cultural effects of the projects on the environment.

Navigation

Straight rivers provide an easier route for movement of transport vessels from one point to the other. The obvious advantages of straightening of rivers to navigation are the following:

There is a swifter flow of water

There is more volume of water flowing past a point at a given time.

Vessels can travel in straight courses saving time, fuel and human effort

Dredging of the channels which often accompany straightening makes the riverbed deeper and stop the river from overflowing its banks.

The excavation of silt and topsoil makes the riverbed more solid to support other necessary structures like bridges

There is Longer sight distance for pilots of ships

There is shorter navigation distances between departure point and destinations (shortest distance between two points is a straight line)

Human effort is also reduced by the use of the auto-pilot facilities.

Water transportation is a more environmentally friendly mode of transport when compared to road and rails because it introduces less Carbon-di-oxide to the environment.

Dams

Dams serve many different functions like provision of drinking water, irrigation, power generation, flood control, and recreation. For good volume of water at very swift speeds, it is customary to make a dam at the downstream of a straightened river.

Impact on the environment

The above reasons obviously impact positively on the economy of the country and also have some positive impact on the environment. However, there are also negative impacts which must be weighed carefully before such projects are commissioned. Some of them are:

Ground water recharge is a major contribution of total volume of water in a river among others. When straightening occurs,

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