RIVERS: River Form and Velocity

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 SWISH! SWOOSH! That's a fast river!


Image: Form TripAdvisor

The two main functions of a river is to transport water and sediments. It is important to understand how the shape of a channel can influence how efficiently a river carries out its functions.

Types of Flow

Laminar

  • Laminar flow is a horizontal movement of water. It is rarely experienced in rivers. However if it did exist in a river channel, it would travel over the sediments of the channel without disturbing it. 

Turbulent

  • Turbulent flow is the dominant flow seen in rivers. It consists of erratic eddies, which moves both vertically and horizontally downstream. 
N.B: Turbulence varies with the velocity of a river, which also relies on the amount of energy available after friction. 

Influence of Velocity on Turbulence

HIGH VELOCITY: If the velocity of a river is high, so will be the amount of energy available after overcoming friction, therefore increasing turbulence. The sediments on the bed will then be disturbed. The faster the river, the bigger and larger the size and quantity of the river's load. 

LOW VELOCITY: If the velocity of a river is low, there will be less energy available after overcoming friction, resulting in a decrease in turbulence. The sediments of the river will remain undisturbed and there will be a significant reduction in the size and quantity of the river load. This decrease in turbulence will also lead to deposition of sediments. 

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