Water on the Land

 

The Hydrological Cycle

The hydrological cycle is also known as the water cycle.

Seas and oceans contain 97 per cent of the world's water, and ice holds 2 per cent. That leaves just 1 per cent of the world's water as fresh water on land or in the air. This water is recycled again and again through the process of evaporation, condensation and water transfers such as surface run-off.

Percolation is the movement of water through lots of tiny particles.

 

 

 

 

 

Drainage Basins

A drainage basin is the area drained by a river/ the area from which a river channel receives water and its tributaries.

 

Some drainage basin key terms are:

Source- The start point of a stream or river, such as a spring.

Mouth- Where a river meets a body of water, such as sea.

Tributaries- A small stream or river flowing into the main river.

Watershed- The line where drainage basins met and which determines to which basin precipitation will go.

Confluence- The point in which two rivers join together, for example a tributary joining a main river.

 

 

How does a River Change Downstream?

 

 

River Characteristics

Upper River

Middle River

Lower River

Landforms

Waterfall, gorge

Ox bow lake, meander

Flood plain

Channel Depth

Shallow

à

Deeper

Channel Width

Narrow

à

Wider

Discharge

Small

à

Larger

Speed

Slow

à

Quicker

Bedload

Larger, greater quantity

à

Limited in quantity

Suspended Load

Limited

à

Greater

Gradient of Land

Steeper

à

Flatter

Width of Valley and Shape

Narrower and V-shaped

à

Wider and U-shaped

Land Use

Pastoral faming, recreation

Residential, farms

Commercial industry, residential

Capacity of River

Less

à

More

Competence of River

Less

à

More

Key Words:

·         Capacity- Maximum load a river can transport.

·         Competence- Maximum size of particle that the river can transport (however due to erosion the particles in the river are smaller downstream).

·         Bedload- How much sediment is carried on the bed of the river. These particles are too big to be carried on the surface.

·         Suspended load- How much sediment is carried on the surface of the river (small enough to not have to be carried on the bed).

The shape of the valley and channel changes along the river depending on whether erosion or deposition is having the most impact (is the dominant process). Geographical models to show this:

 

Long Profile- A long profile of a river shows you how the gradient changes over the different courses.

 

 

Cross Profile- The cross profile shows you what a cross section of the river looks like.

 

Course

Gradient

Valley and Channel Shape

Upper

Steep

V-shaped valley, steep sides

Narrow, shallow channel

Middle

Medium

Gently sloping valley sides

Wider, deeper channel

Lower

Gentle

Very wide, almost flat valley

Very wide, deep channel

 

Vertical and Lateral Erosion Change the Cross Profile of a River

Erosion can be vertical or lateral – both types…