GEOL 101: Geology of Planet Earth
HW#4: Virtual Rivers
READ CAREFULLY TO BE SURE YOU DO THE HOMEWORK CORRECTLY!
This is a two-part assignment, which requires internet access.
You must complete both parts of the
homework to receive full credit.
Homework #4 is due no later than 11:59 pm on Tuesday, April
PART 1: Online “River Discharge” exercise (15 pts)
You can find this exercise online at:
- you may not be able to view the interactive modules on an iPad or a device that does not
- if you have problems running the exercise, try using a different internet browser.
NOTE: You are responsible for completing the “River Discharge” exercise.
You do not need to
complete the “River Flooding” assignment on the same page.
The assignment involves reading each page and answering questions.
The program will not
let you proceed until you answer the questions correctly! At the end of the assignment, you
will receive a “certificate of completion” that you must turn in to me.
DO NOT WAIT UNTIL THE
LAST MINUTE TO DO THIS!!!
YOU MUST COMPLETE THE ONLINE ASSIGNMENT AND TURN IN THE “CERTIFICATE OF
COMPLETION” THAT WILL BE GIVEN TO YOU AT THE END.
Please save your certificate as an image or pdf file (screenshot is fine, but please do not send a.
html file!) and either 1) upload it into the Moodle HW#4: Virtual Rivers assignment, or 2) email
it to me by the due date (emails sent after 11:59 pm on April 26th will not be considered).
then be able to review your certificate and give you the 15 points of credit.
If for whatever
reason you cannot finish the “virtual river” part of the assignment, please send me a screen
shot of the last page you get to and I will give you partial credit.
Here are some hints to help you along:
• The last few pages of this online assignment become more difficult.
Be patient and
work through the problems.
Make sure you read all the text, as you will find the tasks
are not as daunting as they initially appear.
• You may need to hit “refresh” periodically on your computer to observe some of the
• You may need to consult your textbook to answer the questions about meandering
• If you get stuck at the very end: 1 cms = 35.
Part 2: USGS River Gauging (10 pts)
Each winter, a number of rainstorms pummel Los Angeles, causing flooding and in some cases
The objective of this problem set is to have you navigate the United States
Geologic Survey (USGS) Water webpage in order determine the river flows and historical data
related to stream flow in the Los Angeles River drainage basin over the last year.
The USGS maintains gauges on hundreds of US rivers.
This allows them to monitor the flows
throughout the year.
The gauges determine river height (stage), and because they periodically
measure river velocity and know the cross-sectional shape of the river channel, they can
interpret discharge at any time in the river (just like you did in PART 1 of this homework!).
We will look at the gauge on the Los Angeles River near Sepulveda Dam.
You will need to
change certain parameters on the website to answer the questions below.
As usual, input your
answers into the HW#4: Virtual Rivers moodle “quiz” when you have finished.
How to do this part:
First, you need to navigate to the following website:
The left side of the page should look something like this:
Click on “Daily Data”
Then, under “Site Identifier”, click
on “Site Name”
Next, type in “Los Angeles River”
under Site Name, scroll to the
bottom, and hit ‘submit’.
You should be directed to a page with this near the top:
Click on site LOS ANGELES R A SEPULVEDA DAM CA (11092450) to access the site data.
data is from the LA River near CSUN campus.
Scrolling down on the next page, you should see a graph on the screen that shows DAILY
Discharge, in cubic feet per second (y-axis), and dates for the last year (x-axis).
If you see
something different, scroll up and make sure that the start and end dates are May 2015 and
April 2016, respectively.
Use the graph to answer the following questions.
Then go take the HW#4: Virtual Rivers quiz!!
1) By reading the graph on your computer from May 2015 to today, when (what month) was
the highest discharge in the last year?
2) What was the largest flow in the LA river this last year in cubic feet per second?
3) You can assume that the high-discharge events occurred during or after large winter
How many storms produced flows above 300 cubic feet per second (cfs) between
November 2015 and March 2016?
4) Change the “Begin date” for the period of record to today’s date in 1932 (look for box up
and to the right; click “GO” after entering new date).
What was the highest discharge ever
recorded in the LA River based on the graph?
5) When (what year) was the highest discharge recorded in the LA River between 1932 and
today? Do your best to estimate the year.
6) Scroll back up to the top of the page.
Use the drop-down menu for “Available data for this
site” and click on “Location Map.
” This river-gauge is located near the intersection of what two
7) What is the DRAINAGE AREA for the Los Angeles River at this location? The answer is found
on the Site Map for the LA River Sepulveda Dam gauge.
8) Use the drop-down menu for “Available data for this site” and click on “Time-series: Monthly
What month has the largest average monthly discharge in the Los Angeles River?
(Check the box next to 00060, Discharge, cubic feet per second..
and click “submit”).
9) What is the value (in cubic feet per second) of the highest average monthly discharge at the
Sepulveda Dam site?
10) Average flows for the Mississippi River in Arkansas are ~500,000 cfs for much of the year.
What percentage of the average Mississippi River flow is in the Los Angeles River during the
month with peak flow in Los Angeles (divide answer 9 by 500,000 and convert to percentage)?