1. Fluvial Morphology: Landforms Made by Running Water

2. RUNNING WATER  Rivers and Streams
What is the most important geomorphic agent shaping the landscape?
RUNNING WATER  Rivers and Streams
What is the work of rivers and streams?
Erosion
Transportation
Deposition
Fluvial Morphology: Study of Landforms Made by Running Water
FLUVIAL: from the Latin fluvins for ‘running water’ or streamflow 2

3. Fig. 17-3, p. 472 3

4. The Long Profile of Streams
At their headwaters, the grade of a stream is usually steep.
At Mid-streams, the angle of the grade becomes more gently sloping.
Near the mouth of the stream, the grade becomes almost flat.

5. Fig , p. 480 5

6. Stream Stages
Streams also show three stages of gradation from the mountains to the sea, with associated erosional and depositional features:
Youth
Maturity
Old Age

7. Stream Stage 1 - Youth
Characteristics of Youthful Streams
Steep irregular profile
Waterfalls, rapids, and plunge pools
River is deepening its channel
Cutting into bedrock
V-shaped cross-section

9. The Cycle of Erosion Youthful stage headward erosion and
vertical downcutting dominant
steep stream gradients promote valley deepening
narrow, V-shaped valleys 9

10. The channel at upstream point A-B
This channel is located in the stream's headwaters.
The stream gradient and surrounding topography is quite steep.
Stream velocity is at a maximum and cuts a narrow deep channel.
The floodplain is minimal as high velocities carry all sizes of load down stream.
Stream load is high as the steep gradient provides the energy for extensive erosion
Producing a V-shaped river valley.

12. Fig. 17-1a, p. 470 12

13. Fig. 17-CO, p. 468 13

14. Waterfalls and Rapids
Hard rock layers have not yet been smoothed away
A waterfall is a vertical drop in a streambed
Rapids are stream sections with extremely strong currents.
Both are sites of vigorous erosion
Potential Hydro Electric Power

16. Stream Stage 2 - Mature Valley
Characteristics of Mature Valley Streams
Valley widening begins
Meandering Stream
Floodplains

17. Fig , p. 487 17

18. Figure c-d: Stream channel near the middle of a typical stream profile.

19. Causes a sudden reduction in the stream's velocity.
The channel is now leaving the mountainous terrain and entering a landscape that is more gently sloping.
Causes a sudden reduction in the stream's velocity.
The stream adjusts to this change, by depositing most of its coarse stream load onto the floodplain.
The stream also takes on a braided channel form.
These channels are always changing in size, number, and location

20. Lateral Erosion - Valley Widening Begins
Erosion is greatest on the outside bend
Cut-banks
Deposition on the inside bend
Meanders
Widen the valley
Form cutoffs
Create oxbow lakes

21. Fig a, p. 488 21

22. Fig a, p. 489 22

23. 23

24. Stream Stage 3 - Old Age
Characteristics of Old Age Streams
Wide Alluvial Valley Stage
Natural Levees
Depositional feature
Parallel to the stream channel on both banks

25. The channel near the mouth of the stream (Figure E-F).
Extensive flat floodplain is composed of Deposits from channel meandering.
The channel is quite large and U-shaped.
Stream discharge is at a maximum and sediment load is generally composed of finer materials.

26. Fig , p. 491 26

27. A river cut-off results in a portion of the river isolated from the new channel called an oxbow27

28. Rivers drop their load when they enter the ocean and form a ________?

29.   Deltas
Large deposit of alluvial sediment located at the mouth of a stream where it enters a body of standing water.

30. Deltas are created when the sediment load carried by a stream is deposited because of a sudden reduction in stream velocity.
Fig b, p. 491 30

31. Mississippi Birdfoot Delta (Source: NASA).

32. . Some deltas, like the Nile, have a triangular shape
Fig a, p. 491 32

33. Ganges River Delta Image taken 2/28/2000 The Ganges River forms an extensive delta where it empties into the Bay of Bengal. The delta is largely covered with a swamp forest known as the Sunderbans, which is home to the Royal Bengal Tiger.
The Ganges River Delta can be found on Landsat 7 WRS Path 137 Row 44, center: 23.12,

34. p. 494 34

36. Drainage Basins (Watersheds)

38. Fig. 17-5, p. 475 38

39. p. 474 39

40. Lake Itasca is a small glacial lake, approximately 1.8 square miles (4.7 km²) in area, in the Lake District of Northwestern Minnesota. It is the Source[1] of the Mississippi River.

42. Table 17-1, p. 479 42

43. Los Angeles River Now!
2005

45. Is this river aggrading or degrading
Is this river aggrading or degrading? Is it near the headwaters or the delta?

46. Is this river aggrading or degrading
Is this river aggrading or degrading? Is it near the headwaters or the delta? Aggrading, at the delta

47. Is this river aggrading or degrading
Is this river aggrading or degrading? Is it near the headwaters or the delta?

48. Is this river aggrading or degrading
Is this river aggrading or degrading? Is it near the headwaters or the delta? Graded, near the middle or end of its course.
Missouri River, MO

49. Is this stream aggrading or degrading
Is this stream aggrading or degrading? Is it near the headwaters or the delta?

50. Is this stream aggrading or degrading
Is this stream aggrading or degrading? Is it near the headwaters or the delta? DEGRADING, NEAR THE HEADWATERS
Canadian Rockies

51. Fluvial Processes and Landscapes at Different Stream Stages
Youthful
Steep hillsides,
drainage divides predominant,
V-shaped valleys
Headward erosion,
stream downcutting –
vertical erosion
Mature
Rounded hills,
valley walls predominant,
graded streams,
broad floodplains
Lateral erosion,
streams adjust to discharge/load
meandering
Old age
Floodplains, ox-bow lakes,
deltas and alluvial plains,
very low relief
Deposition,
sluggish stream flow,
poor drainage 51