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Rivers

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Rivers Oxbow lakes: an area of poor drainage that occurs when a meander is cut off from the main river channel, forming a lake. Delta: depositional feature found at ... – PowerPoint PPT presentation

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Title: Rivers


1
Rivers
2
Rivers
1. Energy
2. Stages of River Development
3. Drainage Basins
4. Drainage Patterns
5. Geomorphological Features
3
A river is all about energy. If a river is
moving fast (due to gravity) and has a lot of
water it has great energy. With great energy
comes erosion and the transport of the eroded
material. With a loss of energy comes deposition.
4
Energy
  • Features due to erosion or deposition depending
    on speed.
  • Low energy/low speed deposition
  • High energy/high speed erosion

5
Stages of River Development
A Youthful/Upper Stage B Mature/Middle Stage C
Old/Low Stage
6
Physical Geography, Strahler and Strahler
7
Stages of River Development
8
A Youthful Stage
  • Steep, fast, straight, vertical erosion

9
B Mature Stage
  • Less steep, slower, meanders, horizontal erosion

10
C Old Age Stage
  • Flat, slow, meandering, depositional

11
Drainage Basins
  • Area in which all raindrops eventually drain into
    the same river system, ocean, or lake (catchment,
    watershed)

The Amazon Drainage Basin
12
Drainage Basins
13
Drainage Basins
  • Tributaries smaller rivers that drain into
    larger rivers.
  • Interfluves pieces of higher land between
    tributaries.
  • Divide higher ground
  • between drainage basins.

14
Drainage Patterns
  • There are 5 Drainage Patterns
  • Dendritic
  • Trellis
  • Radial
  • Rectangular
  • Deranged

15
Drainage Patterns
16
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17
Dendric Drainage Pattern
  • Flow across level land, merging with other rivers
  • Resemble branching tree

18
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

19
Rectangular
Trellis
20
Radial Pattern
  • Landforms influenced by volcanoes and cone-shaped
    hills.
  • Streams radiate outward in all directions from
    central zone

21
Deranged Pattern
  • No distinct pattern noted
  • Often lakes are found
  • throughout
  • Glaciation has torn
  • the landscape leaving
  • this deranged pattern

22
Geomorphological Features!
LEVEES Form on floodplains when rivers
flood. Water quickly loses its velocity as it
spreads out from the channel and deposition
occurs Heavier sediments tend to settle out
immediately close to the channel and an area of
slightly higher ground is built up on both sides
of the river Because of levees, the river channel
is often built up higher than the floodplains,
which is then very susceptible to flooding
23
Below is a picture of Wilket Creek in Toronto. It
flooded during a violent storm in 2005. What you
see is the sediment that the river was carrying
when it flooded. Note that the sides have heavy
material and the interior is very sandy. The
River could not carry the heavier rocks.
24
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26
Natural levees have been built up by man for
flood control.
http//www.spk.usace.army.mil/what/envir/fldpln/fl
dpln.html
27
Meanders and levees, Red River flood, Manitoba,
1997
http//sts.gsc.nrcan.gc.ca/page1/landf/smanitoba/l
evees.htm
28
  • FLOODPLAINS
  • Valley area through which a river flows in the
    mature (old age) stage
  • Built by river depositing material on the insides
    of the bends as it meanders and when finer
    materials are deposited on the valley floor when
    the river floods.
  • Finer materials traditionally added nutrient
    value to the soil and thus helped to make
    floodplains very fertile areas, supporting large
    populations
  • Unfortunately, large floods also usually meant a
    loss of life as well.
  • A few floodplains support a large portion of the
    worlds population Hwang Ho, Yangtze, Indus,
    Ganges and the Nile.

29
A Landsat 5 image taken Sept. 1992 shows a
section of the Missouri River. The oblique
perspective of this image is looking upstream.
This image has been color enhanced and modified
to show an exaggerated topographic relief. Bare
soil and plowed land appears red, vegetation
appears green, and water is dark blue. A flat
river flood plain can be seen in the center of
the image. Because of the season, most of the
farmland located on the rich and fertile soils of
the floodplain is plowed and devoid of
vegetation.
http//www.geog.ouc.bc.ca/physgeog/contents/11j.ht
ml
30
  • Meander back and forth sweep of a river in old
    age. As a river reaches its mature stage its
    ability to erode diminishes and whenever it does
    erode material it will quickly deposit that
    material. As it erodes material from one bank (on
    the outside - Pool) it deposits material on the
    other bank (the inside - Riffle) and river begins
    to bend or meander.

31
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33
Example of a Pool and Riffle from the Don River
34
  • Oxbow lakes an area of poor drainage that occurs
    when a meander is cut off from the main river
    channel, forming a lake.

35
  • Delta depositional feature found at the mouth of
    a river.
  • Rivers water reaches mouth of river and the
    sediment is carried settles.

36
This is the mouth of the Humber River (flowing
into Lake Ontario). Notice the width of the river
and the flow is very slow.
37
This is near the mouth of the Humber river.
Notice under the bridge the Bulrushes. This
area is also called the Humber Marsh. The river
has slowed down and has deposited some silt or
dirt, allowing the vegetation to grow.
38
  • Estuary the flooded mouth of a river valley. If
    there is an ocean involved we get a mixture of
    fresh and salt water.

39
The End!
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