geography-rivers

Places water can be stored:

On the surface as snow or ice

In the plants and trees

In the lake

In the marsh

In the grass, on the surface

In the soil

In the water table

In the sea in the clouds

Drainage Basin:

Watershed – Edge of drainage basin, joins high points in basin

Source – point at which a river begins

Mouth – point at which a river meets the sea, or inland lake

Tributary – Stream or small river that leads to a bigger one

Confluence – the point at which 2 streams meet

River basin – area drained by a single river system (drainage basin)

Interfluves – ridge of higher ground that lies between 2 rivers

Erosion Processes

Hydrolic power:

The force of water on the bed and banks. Water force removes material from bed and banks. Particulay strong during floods.

 Corrasion:

The sediment rubs against the bed and banks at times of high flow

 Corrosion:

Rock minerals eg. Calcium carbonate slowley disolve in river water, which is sometime acidic.

 Attrition:

Sediment rub against each other, breaking themselves up and reducing each other to sediment.

Transportation

Traction:

Large boulders roll along the river bed

 Saltation:

Small pebbles are bounced along the river bed as the flow changes

 Suspension:

Finer sand and silt particles are carried along in the flow giving the water a brown appearance

 Solution:

Minerals eg. limestone and chalk are dissolved into the water and carried by the flow, they can’t be seen

Waterfalls:

 Falling water and rock

particles wear away soft rock

The hard rock is undercut as

erosion continues

Hard rock collapses and if moved

by the flow. The waterfall moves backwards

 Erosion continues and the waterfall continues to move upstream

leaving a gorge of recession

Ox - bow lake: Semi circular lake formed by a meander being sealed off from the main course of a river.

Meander Scar: Dried up ox – bow lake.

Bangladesh:

Reasons:  Two very large rivers; Ganges and Brahmaputra meet

               Very low lying land

               Monsoon

               Costal storm surges

               Deforestation upstream

               Silting up of riverbeds, decreased capacity

               Population increased

               Urban growth increased surface run off