Lab 14
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South Dakota State University *
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Dec 6, 2023
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Geography 132: Physical Geography-Natural Landscapes + Lab
Lab #5 (30 Points)
Chapter 14: River Systems and Landforms
Ella Jolin
Part I
On the USGS real-time water data website, find a stream gage that is close to where you live or
work.
Click on the state.
Then hover over a couple of the gages to see if you can determine the
location.
The stream gage south of Brookings is site number 06480000.
When you find the site, an entire page comes up with data on that gauge.
Make sure the box at
the top of the page says “Time-Series: Current/Historical.”
In the next box, where it says
“Available Parameters,” “Output,” and “Days” change Days from 7 to 30.
The first graph is the discharge (in CFS).
In the sample graph above (from 2011), you can immediately see that the amount of water
flowing past the stream gauge has gone down for the last 30 days (the blue line).
One interesting
thing they include on this graphic is the median statistics.
This means that the discharge over the
history of the station (57 years in this case) has had as many days over the triangle as below.
So,
for the last 57 years, there have been 28 years where water has been higher than the triangle, and
28 years when the water has been below the triangle on the same date.
1.
Copy and paste this graphic from your site here: (4 points)
2.
Explain the discharge curve and how it compares to the median values: (4 points)
The discharge curve shows that over the past month the Missouri River flowing through Sioux
City, Iowa has gradually increased over time in the amount of water flowing through the stream
gauge. It is super interesting to see the median values within this graph as well. The median
values show a much lower amount of water passing through the stream gauge and really show
the difference in just how much water is flowing through.
The second graph (also from 2011) displays the actually height of the stream at the gage.
This is
the base information from which all the other data are derived.
The key information on this graph is how high the gage height is above the flood stage.
This
graph shows that while the stream height has been going down for the last 30 days, it is still
almost a foot above the flood stage.
The flood stage is the level at which the stream is officially
considered flooded.
The stream height can go up and down quite a bit and still be considered
‘normal.’
3.
Copy and paste your Gage Height graph here: (4 points)
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4.
Explain how the current gage height relates to the flood stage: (4 points)
You can see by looking at the two graphs that they follow patterns in terms of the rises and
drops. The current gauge height compared to the flood stage determines the flood risk: if it's
below, no immediate risk exists; at or near, flooding is imminent; and above, flooding is
occurring or expected. This relationship is crucial for issuing flood alerts, preparing
communities, and initiating emergency responses.
5.
In general, why do you think the graphs look this way for your site?
Are you in a
drought?
Is it wetter than usual?
Explain. (4 points)
While I am not currently located in Sioux City, my family has spoken about the rain they have
gotten over the past month or so. It sounds like it is wetter than usual and this is seen in the
graphs showing gauge level and flood stage. Luckily, I don’t think it is nearly enough rain to
cause any major problems.
Part II
6.
On the aerial photograph of the Cedar River in Iowa below: Please identify and name
three major fluvial landforms present in this river valley (you may put numbers or letters
in the image to identify the landforms). Also, explain how they were formed and what
they can tells us about the geomorphic history of this valley. (5 points)
7.
From this ground photograph taken in northern Utah, please identify landforms
A
and
B
and as best as you can explain their genesis (draw a picture if you need to). (5 points)