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Rattlesnake
Creek, southwestern Wisconsin
The plowed cornfield in the center of this photo is the floodplain of
Rattlesnake Creek, seen in the foreground. During floods, the entire field
is covered with water, as shown in the next photo. |
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Rattlesnake
Creek, southwestern Wisconsin
Identical view to the previous photo, following a rainstorm of several inches
(15 June 1991). Note turbulent flow in the foreground where the stream channel
is located. |
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Mississippi
River, Iowa-Wisconsin
The floodplain of the Mississippi River is several miles wide at this location
on the Wisconsin-Iowa border. Notice the many fluvial features that can
be seen on the floodplain. |
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Grant
River, southwestern Wisconsin
Natural levees are apparent along this stream. On the far bank, the levee
is vegetated, while the plowed field is on the floodplain, slightly lower
in elevation. In the foreground, the surveying instrument sits on the natural
levee. |
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Pecatonica
River, southwestern Wisconsin
This vantage is from a hill, overlooking the floodplain of the Pecatonica
River, which flows along the treeline in the center of this image. The trees
are growing along the natural levee, while the floodplain is plowed for
planting. The standing water at the base of the hill is the poorly-drained
backswamp. |
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Saskatchewan,
Canada
Notice the cutbanks, point bars, cutoffs, and oxbow lakes on the floodplain
of this meandering river. |
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Blake
Fork, southwestern Wisconsin
A more subtle terrace can be seen here. The floodplain occupies only the
low surface immediately adjacent to the stream channel. A higher surface--the
terrace--can be seen at the periphery. |
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Kanab
Arroyo, southern Utah
This stream is deeply incised into its alluvial deposits, having formed
the terraces visible on either side of the channel, approximately 110 feet
above the present channel. The incision (down-cutting) of the channel occurred
between 1880 and 1885 in response to land use changes and intense rainfall
events. |
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western
Colorado
Notice the extensive terraces along this river. |
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Snake
River plain, Grand Teton National Park, Wyoming
In the foreground of the Teton mountains lies the Snake River, flowing through
the forest in the center of the photo. Notice that the forest is growing
on the floodplain, while the lighter-colored sagebrush in the foreground
is on a terrace approximately 20 feet above the present river channel. The
terrace scarp can also be seen on the far side of the floodplain forest.
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Alma,
Wisconsin-Minnesota
Mississippi River Lock and Dam #4 on the Wisconsin-Minnesota border. There
are 29 such structures on the Upper Mississippi River. The dams raise the
water level to allow larger barges to navigate the river, while the locks
allow barge passage around the dams from one “pool,” or reservoir to another.
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Missouri
River, eastern Missouri
Ground view of an old timber wing dam on the Missouri River. This structure
was originally built into the Missouri River channel. Since construction,
sedimentation has substantially extended the floodplain, while the river
channel has become narrower and deeper. |
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Missouri
River, eastern Missouri
Aerial view of the Missouri River, showing wing dams. These rock structures
are built from the floodplain into the river channel, promoting slow river
velocities, low energy, and sediment deposition on the edges of the channel.
The center of the river channel has higher velocities, greater stream power,
and scours the channel deeper. This allows for passage of larger barges,
but is also responsible for loss of floodplain habitat. |
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Mississippi
River, Wisconsin-Minnesota
The “Big Thompson” is a hydraulic dredge used to remove sediment from the
bottom of the Mississippi River navigation channel and pump that material
to storage sites. This technique is used to maintain minimum depth needed
for barges in areas prone to sedimentation. |
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Mississippi
River, Minnesota
Dredge spoil disposal site. Sand and other materials removed from the channel
bottom are left in designated disposal sites along the river. Some concerns
exist over impacts on floodplain habitats. |
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Missouri
River, eastern Missouri
Aerial view of barge navigating the Missouri River channel. The modern river
channel has lost most of its natural characteristics and now resembles an
efficient barge canal. The original channel was much wider and shallower,
with sand bars, side channels, floodplain wetlands, and other diversity.
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Missouri
River, eastern Missouri
During the “Great Flood of 1993,” flood control levees along the Missouri
River failed in places where the river’s energy could not be contained.
Notice the scour hole in the floodplain downstream of the meander bend.
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Missouri
River, eastern Missouri
Scour hole at levee break. When earthen levees are breached, water quickly
erodes a hole in the levee and scours into the floodplain. Such scour holes
were often 50 feet deep, with removed material deposited elsewhere on the
floodplain. |