Lab_Streams
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Durham Technical Community College *
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Course
230
Subject
Geography
Date
Dec 6, 2023
Type
Pages
2
Uploaded by AmbassadorComputerHorse22
Laboratory Assignment – Streams
Figure 1. Channel Types in Map View
Assignment
Part 1 – Evaluating Cedar Creek using a Topographic Map
Open the Mt. Ennis 15 Minute Topographic Map, located
here
.
Take a few moments and orient yourself to the map.
Some rivers are subject to large floods, either seasonal or periodic.
In mountains, this flooding is often due to snow melt.
In drylands, it is caused by thunderstorms.
During such times, rivers transport large volumes of sediment.
This produces
two characteristic features to form, braided channels and alluvial fans. Both features are relatively common in arid
mountainous regions, such as the Ennis, Montana area.
1.
Determine the gradient (slope) along the following stretches (in feet/miles).
Remember, to measure a gradient
(slope), pick two points along the stream and determine their elevations using the contour lines.
Then, measure
the distance between them (measure along the stream).
Gradient can be calculated by dividing the difference in
elevation (in feet) by the distance between the two points (in miles).
a.
Along Cedar Creek in the forested section of this map (southeast corner) between sections 22 and 29.
200 ft. Per mile
b.
Along Cedar Creek on the alluvial fan (just pick one of the distributaries to measure)
160 ft. Per mile
c.
Along the Madison River
36.96 ft. Per mile
2.
What main stream channel types (braided, meandering or straight) are…
a.
Along Cedar Creek in the forested section of this map (southeast corner) between sections 22 and 29.
straight
b.
Along Cedar Creek on the alluvial fan
straight
c.
Along the Madison River
braided
3.
Based on your data, what relationship do you see between gradient (from Question #1) and stream channel type
(from Question #2)?
The higher the gradient the faster the stream flows and the lower the gradient it becomes meandering or braided.
4.
What was the source of the sediments that have accumulated on the Cedar Creek Alluvial Fan?
Mountains east of the Cedar Creek Alluvial Fan
5.
What happens to the stream gradient along Cedar Creek as it enters the alluvial fan?
How does this contribute to
the formation of the alluvial fan?
It becomes straight and carried all the sediment downstream which created the alluvial fan.
Part 2 – Evaluating Cedar Creek using the USGS Streamer Webite
6.
Go to the
USGS Streamer website
.
For hints on how best to use this website,
you can watch this short video
.
Click on ‘Go To Map’.
Zoom into Montana and find Cedar Creek (it is located southwest of Bozeman – look for
Ennis Lake, too).
Click on ‘Trace Downstream’ on the top bar of the website and then click the curser on Cedar
Creek, close to Ennis Lake.
Describe the path (which rivers) that the water that flows in Cedar Creek will follow
as it flows downstream to sea level.
7.
Click on ‘Trace Report’ and view the ‘Detailed Report’.
a.
In how many named streams does the water flow downstream from this point?
Cedar creek, Madison river, Missouri River, Mississippi River, old river, Atchafalaya river, red river, chute of island #8
b.
Through how many cities does the water flow downstream from this point?
340
c.
What is the total length of this stream trace?
3,782 miles
8.
Go back to map, click on ‘Trace Upstream’ and then click just downstream of Ennis Lake (on the north end of it).
Cedar Creek isn’t the only stream that flows into this lake.
Click on ‘Trace Report’ and view the ‘Detailed
Report’.
a.
How many named streams flow into Ennis Lake?
Atchafalaya river, Madison river, Missouri River, Mississippi River, chute of island # 8, old river, red river
b.
Through how many cities do these streams flow through?
339
c.
What is the total length of this stream trace?
3,761 miles
9.
Why would a community located on or near a stream want to know where its stream water comes from?
It can be helpful in determining the catchment areas and subsequent construction of rivers/ponds. Also, to design houses
to prevent water logging during rainy days.
10.
Why would a community located on or near a stream want to know where its water goes after passing its
community?
In case of any pollutants in the water and being able to understand any waste leaving the area.
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