GEOL 1301 - Lab 08 - Streams
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University of Texas, Arlington *
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Geology
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Feb 20, 2024
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GEOL 1301 Name: Jonathan Venegas
Streams Lab
A
Learning and Lab Objectives: For this lab, we will learn about stream channel
types and their relation to stream gradient, along with other stream characteristics. In
the lecture, we learned about surface water, which streams are a part of. In the lab,
we will look further into the characteristics of the stream itself and the channel that it
flows within.
A stream’s ability to carry sediment increases with its velocity, which depends on its
gradient. The gradient is defined as the change in elevation divided by the horizontal
distance the stream travels and is usually expressed in ft/mi or in m/km. Typically,
stream channels are narrower in a steeper terrain, and a stream channel widens
downstream. Terms used to describe the channel type of a stream are straight,
braided, sinuous, and meandering.
The sinuosity of a stream is a measure of how winding the course of a stream is. To derive a stream’s sinuosity, the length of a channel must be measured and divided by the straight-line distance down the valley
. A stream is called “meandering” if it has a sinuosity greater than 1.5.
Lab instructions: For this lab, your TA will review important stream characteristics,
and then you will examine the map you used for your topography lab. Using a string
and a ruler, you will measure the stream and answer a few questions about its
characteristics.
Supplies needed for this lab: Ruler, simple calculator.
Readings: Chapter 18 (ignore deltas and floods)
Material needed:
http://water.usgs.gov/edu/earthrivers.html
http://water.usgs.gov/edu/watercyclestreamflow.html
http://en.wikipedia.org/wiki/Drainage_basin
http://en.wikipedia.org/wiki/Channel_types
http://en.wikipedia.org/wiki/Oxbow_lake
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Stream and Channel Characteristics
On the topographic map displayed in the lab, find Henry House Creek (hint: It is located in the western half of the map) and follow its course.
1. In which direction is it flowing? How do you know?
The creek flows south because the falls originate in the north until it reaches the creek.
2. Compare the channel of the Henry House Creek north of 34°21’30” with its channel south of 34°20’00”. Describe their differences (at least two).
The one North is straighter while the one in the South is more like a meandering river. They flow in different directions.
3. The Henry House Creek is a tributary to another creek. What is the name of that creek?
Caddo Creek.
4. In which direction is the creek that you named in question 4 flowing?
It flows towards the east and then it will move a little southeast. After it will move east again.
5. Along the creek from questions 3 and 4, you will find a river-related feature at a location marked “X”. What feature is this, and how did it form?
It forms an oxbow take due to the meandering river going off its course.
6. Derive the gradient of the Henry House Creek between points C and C’. Hint: you
first have to find out the elevations at these two points and calculate their difference. Then you have to measure the distance along the river channel between these two points (using the string provided in the lab) and compare it to the scale provided on 2
the map. From these two numbers, you can calculate the gradient (see first page of the lab handout). Calculate the gradient in ft/mi. Show your work.
C=1050 C prime =1000, 1050-1000=50=elevation change
Distance between C and C’= 108,000 miles
108,000/50=2160ft/mi
7. Now perform the same task for the river channel between points D and D’.
D=850 C’=835 850-835= 15 = elevation change
Distance between D and D’ = 96,000 miles
96,000/15 = 6400 ft/mi
8. Measure the sinuosity of the Henry House Creek between D and D’. Would you call the creek “meandering”? Why or why not?
Yes it would be called meandering because there are many bends present in the river, too many for it to be straight, and there are no intersecting.
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