BASINS2: Using the QUAL2E Model

Prepared by Ann Quenzer, Patrice A. Melancon, Dr. Neal Armstrong, and the USEPA

 Table of Contents

Goals of the Exercise

This exercise is structured after the EPA BASINS Training Workshop for BASINS2 training.

This exercise will familiarize the user with the tools available in BASINS. The exercise shows how the QUAL2E model works using Onion Creek Watershed in Texas. For your reference, Onion Creek is a tributary of the Colorado River which is located in the south end of Austin, TX. The objective of the model is to model the nitrogen cycle. the phosphorus cycle, and COD within the river reaches. The exercise will also model Total Suspended Solids.

Computer and Data Requirements

ArcView 3.0a and BASINS2 software are needed for the exercise. The BASINS2 software can be downloaded from the EPA Internet Site: http://www.epa.gov/OST/BASINS/.   In addition, you should download the Texas data files, the tutorial files, and the User's Manual.  The User's Manual will walk you through the installation of the files.  In addition, there are download instructions on the webpage.

The computer requirements needed to run the BASINS software are listed below:
Computer Pentium w/ CD-ROM
RAM 32 MB
Free disk space 400 MB for an average State
Operating System Windows 95
GIS software ArcView 3.0a

We recommend that you do not attempt to run this exercise on a machine that is running Windows NT - as of mid May 1998,
the BASINS2 software still had some bugs associated with Windows NT that needed to be worked out.
 

Getting Started

Using the Windows Start button, click on the Programs icon which will lead you to the Basins program. Click on the Basins icon. Open the project called texas.apr.

In order to get the texas.apr project, a data extraction must be done along with the build program. These two process are explained in the BASINS users manual. They are not discussed in this exercise due the time involved.

** Immediately save the project to a directory of your own with a unique name.**

The BASINS program saves to its own folder as the default. If others have access to the machine that you are working on they may have access to your files which are created while you work. You will not have the option to save most of your data files else where, but you will have the option to save your project to where you want it. This will partially secure your project as you own. The reason for this is because this version of BASINS2 is still in Beta format and some of the bugs have not been worked out.

Data Preparation in Basins

  1. Make the Basins View active. Display and activate the Reach File theme.
  2. From the Theme menu, select Query. Locate the following reaches by double clicking on the field Rivrch and the following reach.: 12090205002, 12090205003, 12090205004, and 12090205005. Your query will look something like this {Rivrch = "12090205002" or Rivrch = "12090205003" or Rivrch = "12090205004" or Rivrch = "12090205005"}.  This is part of Walnut Creek within the City of Austin TX.
  3. From the Models menu, select QUAL2E.
  4. Select 1993 as the point source discharge year.
  5. You will then be informed by a message box that COD and the nitrogen and phosphorus cycles will be modeled as defaults.
  6. Next, you will be prompted to select up to 3 conservative substances and 1 nonconservative substance. The numbers in front of the substance name indicate the number of dischargers in the selected reaches and the total number of pounds discharged per year. On the “Select 1st conservative constituent” screen, select Solids, Total Suspended. Click OK.  You can make the message box bigger to read the list better.
  7. Click CANCEL when prompted for a second conservative substance.
  8. Click CANCEL when prompted for the nonconservative substance.
  9. Read the message on the following screen on how to load the the BASINS-built input file (QUALINP.RUN) in QUAL2E. Click OK.

    10. NOTE: If others have run Qual2E on the same machine before you have, the input file will be over-written. As a courtesy to others, save your input and output files to a disk or your individual workspace and delete these files when you are finished with this exercise. Output files will be named with an .out extension or a .q2e extension in the basins/modelout/ folder. The input file has an .run extension in the models/qual2e/ folder. Be careful what you delete so that you do not delete any program files or other important files.

Using Qual2E
  1. Once the QUAL2E windows interface appears, select the Import menu and choose Run file. Recall the name of your input file is QUALINP.RUN. Select this file. Performing this action loads data from BASINS into QUAL2E.
  2. Click on the Index button and select the “Screen 2” button to jump to Stream Reach System screen. Note that RF1 reach numbers appear in the Reach Name column. QUAL2E uses its own numbering in the left column (i.e. 1, 2, 3 … etc). Write original RF1 reach numbers (CUSEG) and corresponding QUAL2E reach numbers for future references.
  3. Click on the Index button and select “Screen 11” to enter hydraulic data. Data elements, except for Manning’s roughness coefficient, in the Hydraulic Data screen are not available from RF1 database. Therefore, you will have to supplement the data from other sources. Calculate the depth versus flow and velocity versus flow relationships as shown in class.
  4. Look at all of the "Screens" to see if the numbers make sense. Use the Next, Back or Index buttons to move from screen to screen.
  5. In the last screen, click on Run to execute the model.
  6. Click on the Yes button when you are asked if you want to view the model output. It will display the model output using a text editor. Check to make sure all of the output makes sense. Close the window when you are done.
  7. Click the Graphics button to begin the plotting program. Click the REACHES button. This screen displays the reach network and the computational elements used for the simulation. Note the locations of point sources.
  8. Click File and Exit to exit this screen.
  9. Select 1 as Starting Reach and 3 as Ending Reach. Note that the Flow versus Distance option is selected as the Type of graph.
  10. Click the Run button and press OK to accept that the plot will be saved as the selected file. The graph shows a plot of flow versus distance.
  11. Next, plot water quality constituents versus distance.
  12. Select 1 as Starting Reach and 4 as Ending Reach in the first graphics screen.
  13. Select the Water Quality Constituents versus Distance option selected as the Type of graph and click the Next button.
  14. Select Biochemical Oxygen Demand and Dissolved Oxygen by holding the shift key and clicking the mouse.
  15. Click the Run button and press OK when you are asked to confirm the filename in the Graphics Selection screen.
  16. You can also plot the conservative constituent.
  17. Close the plot window when you are done.
  18. Also close the QUAL2E Graphics window.
Answer the following questions:
    1. Do you see three jumps in the plot in the flow vs. distance plots?__________________________
    2. What contributes to the increase of stream flow at these three locations? ______________________
    3. What is accountable for the changes in slope in the constituent plots?____________________
Working with Qual2E
  1. To determine what facilities are discharging to one of the four stream segments modeled, click on the Index button in the QUAL2E window and click on the Screen 17 button to go to the Point Loads and Withdrawals screen.
  2. There are six dischargers listed. Two items actually indicate that four dischargers are combined in each of the elements. QUAL2E allows only one discharger in a computational element (refer to Screen 3). Therefore, if there are more than one facilities discharging to a computational element of a reach they must be added and the total flow and loads are considered as point source contributions to the reach.
  3. Open BASINS View in ArcView.
  4. Activate Permit Compliance System theme and click on the Open Tables button, .
  5. Do a query to find the facilities that discharge into CUSEG 12090205002, 12090205003, 12090205004, and 12090205005. Note the facility names and mile points. In some cases mile points of facilities are missing in the PCS database and the mile point field contains 0.0 miles.
  6. Update the mile point information of the facilities in QULA2E. Find the length of each computational element (Screen 3, Computational Element).
  7. Calculate the computational element that each of the dischargers should be in.
  8. In the Computational Element screen change the type to P for any elements that have missing dischargers. Also change any elements from P to S that have too many dischargers.
  9. Now go to the Point Loads and Withdrawals screen and you may see blank lines at the bottom of the table.
  10. Substitute 4 Disch. with a less number of facilities that are dischaging to that element, if there are less dischargers at that element. Also change the amount of discharge to that element, if it is known.
  11. Type the facility name in the blank line. Assume that the point source discharge information for any new discharges are as follows: Treat (%) 0.0 Flow (m 3 /s) 0.5 Temp ( o C) 23.0 DO (mg/L) 5.2 BOD (mg/L) 3.0 Soli (mg/L) 40.0 NH3-N (mg/L) 0.0 Type 0.0 for all other parameters.
  12. Save the project.
  13. Run the model and plot graphs to view results.
  14. To determine if you are modeling mean flow, low flow or another flow condition, open Screen 16, Headwater Source Data, in QUAL2E and write Headwater Names and corresponding flow values (note the units).
  15. Open BASINS view in ArcView and activate the Reachfile 1 theme.
  16. Select the inquiry tool, and click on the reaches you are simulating in QUAL2E.
  17. Write MNFLOW and SVTNFLOW values of each reach. These flow values are in cubic feet per second. Convert them to m 3 /s by dividing the numbers by 35.3.
  18. Now compare these numbers with flows listed in Headwater Source Data screen of QUAL2E.
  19. Substitute flows in the Headwater Source Data screen with mean flows you read from BASINS ArcView and converted to m 3 /s.
  20. Run QUAL2E for mean flow condition and view the graphs.
  21. Change BOD of reach 12090205004 to 26 mg/L in Screen 14, Initial Conditions of the Stream.
  22. Run the model and view graphs.
  23. Double the flow from one of the sources in the Point Loads and Withdrawals screen.
  24. Run the model and view graphs.
Answer the following questions:
  1. List the six dischargers according to QUAL2E.___________________
  2. What are the discharge locations (mile point) of the facilities discharging to each reach?
  3. If the initial concentration of BOD in reach 12090205004 is 26 mg/L, what is the impact on model results?
  4. If the Griffin facility doubles its current discharge, what happens to DO and BOD concentrations in the stream?
Visualization of Qual2E

In BASINS View, pull down the MODELS menu and select VISUALIZE.

Choose QUAL2E Output File in the output file type selection dialog box.

Specify the QUAL2E output file name in the file selection dialog box. The QUAL2E output files are located in the \BASINS\MODELS\QUAL2E directory. There are two QUAL2E output files. Both have the same name as the QUAL2E input file (e.g., QAL2E002.INP), but each has a different extension. The summary output file has an OUT extension, which is displayed after each simulation run within the QUAL2E interface. The other output file has a DOU extension (e.g., QAL2E002.DOU), and it is used in the QUAL2E output visualization process. Therefore, in the file selection dialog box you will prompted to choose only the DOU file.

Click on OK after you have selected the output file name.

Select the output element you want to visualize in the dialog box.

The next dialog box asks whether you want to use previously saved ranges to group results for visual display. If you want to use an existing scheme, click on YES and you will be asked to specify the name of the scheme. Click on NO if you do not have any.

From the Classification Scheme Definition box, you can select default settings of classes, modify default classes, or edit previous settings of the saved schemes.

The next dialog box gives you the option to save the current settings of the classification scheme for future use. If you do not want to save then, click on NO. Otherwise, click on YES and you will be prompted to provide a name for the scheme.

The Visualize screen displays the color-coded reaches that were included in the QUAL2E simulation. One of the two windows has the banner QUAL2E: F=filename, output element name (e.g., Biochemical Oxygen Demand). Notice that the new active theme includes the selected output element name and the legends for the classification scheme. You can double-click the left mouse button on the window banner for a full screen view. You might want to check the Reach File,V1 theme to view other reaches in the cataloging unit. Other themes can be viewed to examine related information with the model visualization.

These materials may be used for study, research, and education, but please credit the authors and the Center for Research in Water Resources, The University of Texas at Austin. All commercial rights reserved. Copyright 1998 Center for Research in Water Resources.