Fluvial Morphology:
Landforms Made by Running Water
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
SOURCES OF WORLD’S WATER
Source
Oceans
Ice Sheets and Glaciers
Ground Water
Lakes (Fresh)
Inland Seas / Salt Water Lakes
Soil Moisture
Atmosphere
Rivers*
% of Supply
97.2
2.15
0.62
0.009
0.008
0.005
0.001
0.0001
* Running water or streamflow is the most significant agent sculpting the
Earth’s land surface
Sources of stream flow
 25 - 40% of total precipitation runs off as storm flow, and becomes stream flow
 The rest of stream flow comes from groundwater discharge, as base flow
River Quiz:
http://www.ilike2learn.com/ilike2learn/Rivers/Longest%20Rivers.html
Amazon: http://www.youtube.com/watch?v=ta35C488dnE
Rills  Gullies  Streams

Stream Order,
Drainage Basin,
Watershed
and
Drainage Divide
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.
Southern California
Watersheds
3-D Drainage System and Stream Model
Fig. 17-3, p. 472
Drainage Patterns and Topography
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
Stream Gradients
Fig. 17-11, p. 480
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
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
V-shaped Valleys
Waterfalls
Stream Stage 2 – Mature Valley
Characteristics of Mature Valley Streams
 Valley widening begins
 Meandering stream  lateral erosion + deposition
 Braided channel  deposition (sand bars)
 Floodplains
Meandering
Streams
Meandering Stream
Fig. 17-24a, p. 489
Braided Stream Channel of the Brahmaputra River in Tibet
Tectonic Uplift,
Stream Rejuvenation
and Alluvial Terraces
Tectonic Uplift,
Downcutting,
and
the Grand Canyon
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
Floodplain Features
Fig. 17-26, p. 491
Mississippi Floodplain
Delta
http://www.youtube.com/watch?v=AjZLAw_lgZ4&feature=related
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 
Mississippi Birdfoot Delta
Source: NASA
Ganges-Brahmaputra River Delta
From Landsat 7 WRS Path 137 Row 44, center: 23.12, 90.37. Image taken 2/28/2000
Fluvial Processes and Landscapes at Different Stream Stages
Stage
Landscape
Processes
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
Floodplains, ox-bow lakes,
deltas and alluvial plains,
very low relief
Deposition,
sluggish stream flow,
poor drainage
Old age
Los Angeles River Now!
2005 Flood