# Life Cycle of a River-Stream Orders, Erosion, Transportation and Deposition YouTube Lecture Handouts

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Stream order is a measure of the relative size of streams.

The smallest tributaries are referred to as first-order streams, while the largest river in the world, the Amazon River in South America, is a twelfth-order waterway.

Strahler modified Horton method for Stream order.

He explained assigning stream numbers. He explained that each headwater perennial Stream has an order of 1, and then at the confluence of two 1st order Streams we have order of 2. In this method, the confluence of two 2nd order Streams results in order 3 stream, and so on

This process goes on and on.

In mathematics, the Strahler number or Horton – Strahler number of a mathematical tree is a numerical measure of its branching complexity.

There are 4 process involved in erosion. These are:

• Hydraulic Action - where the sheer force of the water erodes the stones, bed and banks of the river
• Corrasion - where stone sin transport are thrown into the bed and the banks eroding them
• Corrosion - where weak acids within the water react with the rocks and bed and bank of the river
• Attrition - where stones in transport are thrown into one another

Process of transportation includes:

Solution - minerals are dissolved in water and carried along in solution

Suspension -fine light material is carried along in the water

Saltation - small pebbles and stones are bounced along the river bed

Traction - large boulders and rocks are rolled along the river

Hjulstrom curve is a graph explaining relationship between the size of sediment and the velocity required to erode (lift it) , transport it and deposit it.

Competence is the maximum size of load that a river can carry, and this is largely determined by velocity.

Manishika