Action of Running Water II

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Welcome to class! 

In today’s class, we will be talking more about the action of running water. Enjoy the class!

The Action of Running Water II

MIDDLE COURSE OF A RIVER

Characteristics of the middle course of a river

1. Lateral erosion is dominant over vertical erosion, resulting in widening of the river valley.
2. There is an increase in the volume of water due to the addition of more water from tributaries.
3. There is an increase in the load of the river.
4. The work of the river is mainly transportation with little deposition.

EVALUATION

1. Mention the stages of a river and a feature in each stage.
2. Mention three characteristics of a river in its middle course.

PROCESSES OF RIVER TRANSPORTATION

The load of a river is carried or transported along the course of a river through four main processes. These are:

1. Solution
2. Suspension
3. Saltation
4. Traction

FEATURES OF MIDDLE COURSE OF A RIVER

1. Wide V-shaped Valley
2. Meander
3. River Cliff and Slip – off Slopes
4. Interlocking Spur

LOWER COURSE OF A RIVER

Characteristics of the lower course of a river

1. The main work of the river is the deposition of materials.
2. There is active lateral erosion.
3. There is lowering of the gradient of the valley floor.
4. There is a drastic reduction in the speed of the river.

FEATURES OF LOWER COURSE OF A RIVER:

1. Flood plain
2. Levees
3. Ox-bow lake
4. Braided river
5. Delta

DRAINAGE PATTERN

A river system which includes the main river and its tributaries may develop certain patterns from their basin and the types of drainage patterns include:

1. Dendritic drainage pattern: In this type, the tributaries called the subsequent rivers to join the main river called the consequent river at an oblique angle. It is a tree-like structure i.e. like branches of a tree which develop on homogenous rocks of bed.
2. Trellised drainage pattern: This is formed due to the alternate layers of hard and soft rocks, resulting in the tributaries following the pattern of the rock structure and at a right- angle to the main river in form of rectangular shape.
3. Radial drainage pattern: The streams or tributaries flow outward and down the hill thus given rise to a radial drainage pattern like the shape of a bicycle wheel.
4. Centripetal drainage pattern: In this type, many rivers or streams flow from different directions into a lake.
5. Annular drainage pattern: The mainstream or river almost form a concentric ring around a highland i.e it almost flows round or encircles a hill.

IMPORTANCE OF RIVERS

1. Medium of transportation.
2. Generation of hydro-electric power (H.E.P) where rapids and waterfalls exist.
3. Provides water for irrigation purposes.
4. Provision of water for domestic and industrial purposes.
5. Formation of flood plain by rivers also provides fertile soil for agricultural activities.
6. Rivers provide food e.g. fish, prawns, crabs, etc.
7. It provides employment to many people e.g. fishermen and canoe builders.
8. Some rivers act as political boundaries between states, regions and nations.
9. Some rivers are centres of tourist attraction and may generate foreign exchange. 

GENERAL EVALUATION

1. What is running water?
2. State the stages of a river.
3. Explain the processes of river erosion.
4. State the processes of river transportation.
5. Mention the features of a river in its lower course.

 

In our next class, we will be talking about Action of Wind.  We hope you enjoyed the class.

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