rivers and geomorphology

Rivers and GeomorphologyCGF3M

Rivers

1. Energy

2. Stages of River Development

3. Drainage Basins

4. River Patterns

5. Geomorphological Features

Energy• Features due to erosion or deposition

depending on speed.• Low energy/low speed = deposition• High energy/high speed = erosion

Stages of River Development

A: Youthful/Upper StageB: Mature/Middle StageC: Old/Low Stage

Stages of River Development

A: Youthful Stage• Steep, fast, straight, vertical erosion

B: Mature Stage• Less steep, slower, meanders, horizontal

erosion

C: Old Age Stage• Flat, slow, meandering, depositional

Drainage Basins• Area in which all raindrops eventually

drain into the same river system, ocean, or lake (catchment, watershed)

The Amazon Drainage Basin

Drainage Basins• Tributaries: smaller rivers that drain into

larger rivers.• Interfluves: pieces of higher land between

tributaries.• Divide: higher ground between drainage basins.

Drainage Basin

Drainage Patterns• Main river = trunk• Tributaries = branches• Distributaries = roots

Drainage Patterns• 5 Drainage Patterns:

– Dendritic – Trellis – Radial– Deranged– Rectangular

Drainage Patterns

Dendric Drainage Pattern• Flow across level land, merging with other

rivers• Resemble branching tree

Trellis and Rectangular• Ground is made of folded bedrock, rivers

may follow a straighter course along the softer bedrock, with hard rock on either side.

• Often in mountainous areas.• Trellis: one main trunk• Rectangular: square pattern

Radial Pattern• Landforms influenced by volcanoes and

cone-shaped hills.• Streams radiate outward in all directions

from central zone

Deranged Pattern• No distinct pattern noted• Often lakes are found throughout• Glaciation has torn the landscape leaving this deranged pattern

Geomorphological Features• Levees: sediments deposited in the

stream channel that contain the water. (ridges).

Geomorphological Features• Meander: sinuous back and forth sweep of

a river in old age.• Meander scar: an oxbow lake that has

dried up leaving a dry hollow where the river channel had been.

Geomorphological Features• Oxbow lakes: an area of poor drainage

that occurs when a meander is cut off from the main river channel, forming a lake.

Geomorphological Features• Delta: depositional feature found at the

mouth of a river.• River’s water reaches mouth of river and

the sediment is carried settles.

Geomorphological Features• Estuary: the flooded mouth of a river

valley.