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Fluvial Morphology: Landforms Made by Running Water

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Presentation on theme: "Fluvial Morphology: Landforms Made by Running Water"— Presentation transcript:

1 Fluvial Morphology: Landforms Made by Running Water

2 RUNNING WATER  Rivers and Streams
What is the most important geomorphic agent shaping the physical 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


Source % of Supply Oceans Ice Sheets and Glaciers Ground Water Lakes (Fresh) Inland Seas / Salt Water Lakes Soil Moisture Atmosphere Rivers*   * Running water or streamflow is the most significant agent sculpting the Earth’s land surface

5 Sources of stream flow % of total precipitation runs off as storm flow, and becomes stream flow The rest of stream flow comes from groundwater discharge, as base flow

6 River Quiz: Amazon:



9 Stream Order, Drainage Basin, Watershed and Drainage Divide
Rills  Gullies  Streams Stream Order, Drainage Basin, Watershed and Drainage Divide

10 Mississippi-Missouri Drainage Basin
Lake Itasca is a small glacial lake, approximately 1.8 square miles in area, in the Lake District of Northwestern Minnesota. It is the source of the Mississippi River.

11 Southern California Watersheds

12 3-D Drainage System and Stream Model
Fig. 17-3, p. 472

13 Drainage Patterns and Topography

14 The Long Profile of Streams
At their headwaters, the grade of a stream is usually steep At mid-course, the grade becomes more gently sloping Near the mouth of the stream, the grade becomes almost flat

15 Stream Gradients Fig , p. 480

16 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

17 Stream Stage 1 – Youth Characteristics of Youthful Streams
Steep, irregular profile Headward erosion  Waterfalls, rapids, and plunge pools River is deepening its channel Cutting into bedrock – Vertical erosion* V-shaped cross-section  *Reflects the propensity of streams to try and reach their ultimate base levels (i.e., sea level) or secondary base levels

18 V-shaped Valleys

19 Waterfalls

20 Stream Stage 2 – Mature Valley
Characteristics of Mature Valley Streams Valley widening begins Meandering stream  lateral erosion + deposition Braided channel  deposition (sand bars) Floodplains

21 Meandering Streams

22 Meandering Stream Fig a, p. 489

23 Braided Stream Channel of the Brahmaputra River in Tibet

24 Tectonic Uplift, Stream Rejuvenation and Alluvial Terraces
Downcutting, and the Grand Canyon

25 Stream Stage 3 - Old Age Characteristics of Old Age Streams
Wide Alluvial Valley Stage The channel is quite large and U-shaped Stream discharge at a maximum and sediment load composed of finer materials Natural Levees, parallel to the stream channel on both banks Other depositional features, including Delta

26 Floodplain Features Fig , p. 491

27 Mississippi Floodplain

28  Delta Large deposit of alluvial sediment located at the mouth or estuary of a stream where it enters a body of standing water, usually a ocean or a lake. Deltas are created when the sediment load carried by a stream is deposited because of a sudden reduction in stream velocity. Delta surface is characterized by distributaries Some deltas, like that of the Nile, have a typical triangular shape, like the Greek letter 

29 Mississippi Birdfoot Delta
Source: NASA

30 Ganges-Brahmaputra River Delta
From Landsat 7 WRS Path 137 Row 44, center: 23.12, Image taken 2/28/2000

31 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 Old age Floodplains, ox-bow lakes, deltas and alluvial plains, very low relief Deposition, sluggish stream flow, poor drainage

32 Los Angeles River Now! 2005 Flood

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