Equal Discharge Increment (EDI)

Description

Equal-discharge-increment method (EDI)samples are obtained from the centroids of equal discharge increments across the cross section. This method requires some knowledge of the distribution of streamflow in the cross section, based on a long period of discharge record or on a discharge measurement made immediately prior to selecting sampling verticals. If such knowledge can be obtained (such as with an ADCP), the EDI method can save time and labor (compared to the equal-width increment method)especially on the larger streams, because fewer verticals are required (Hubbell and others, 1956). (Edwards and Glysson,1998)

EDI is written in Matlab and compiled to allow users who do not have Matlab to run the program. EDI facilitates easy use of an ADCP discharge measurement for computing the locations and associated depth and water velocity for collecting Equal-discharge-increment method samples.

Input for the program is a file compatible with the TRDI Classic ASCII output.

EDI allows the user to change the default increments of 10, 30, 50, 70, and 90 percent of the discharge to any desired flow percentage between 0 and 100. The location of the sample is computed by finding the 1st ensemble (referred to that the target ensemble) that results in a cumulative discharge that exceeds the target discharge computed as the Target Percentage multiplied by the Total Discharge. The distance from the starting bank is computed as the Distance Made Good (straight-line distance from starting location) to the target ensemble plus the starting edge distance and a user provided zero distance offset. Therefore, it is important that the transect used traverse the channel in a straight line. The depth is the simple mean of the beam depths for the target ensemble. The velocity is the magnitude of the mean velocity of the measured portion of the velocity profile for the target ensemble. No accounting for the unmeasured portion of the velocity profile is included.

How to Download the Software

In order to provide support for EDI and to provide an efficient means to communicate with users and allow users an efficient and organized means of providing suggestions and comments, EDI can only be downloaded from the OSW Hydroacoustic Forums. To access the OSW Hydroacoustics Forums you must be a registered user of the forums.

Register for access to OSW Hydroacoustics Forums

Registered Users

Installation Instructions

1. Install the appropriate Matlab Component Runtime libary, if necessary. For instructions on how to determine if you have the needed library and/or to install the library see Matlab Component Runtime Library Download and Installation
2. Download the EDI executable from above.
3. Select a directory and unzip EDI to store the EDI.exe adn gui-EDI.ctf files. These files must be in the same directory but can be in any directory where the user has read/write permission.
4. Run the program by double-clicking on EDI.exe in Windows Explorer or My Computer. You may wish to create a shortcut to EDI.exe in a convenient location in the Start Menu or on the Desktop.

Operational Instructions

1. Select a transect collected with an ADCP and process the transect to a TRDI compatible Classic ASCII output file.
2. If you created a shortcut to EDI.exe during the installation, you can run the program using the shortcut. Otherwise you can run the program by double-clicking on EDI.exe in Windows Explorer or My Computer. Note: It may take more time than expected for the EDI GUI to appear, particularly the first time it is run. Please be patient.

3. Click on "Open File" and navigate and open the desired *t.000 or *ASC.txt depending on version of WinRiver.
4. A note at the bottom of the table will notify you that file is being read. After the file has finished loading, the name of the file will appear below the EDI table. Reading the file can be a slow process, be patient.
5. If you collected GPS data along with the ADCP data and you use DeLorme TopoQuads to assist in navigating to the sample locations, clicking the Create TopoQuads check box will create a TopoQuad compatible file that when loaded into TopoQuads will mark each computed sample location. You will be prompted to name this file after you click on Compute Stations. The file will be located in the same directory as the ASCII file you processed.
6. The standard set of discharge percentages are set by default but they can be edited and changed by the user.
7. If the stationing being used does not start at zero use the zero distance offset to adjust the distance values. The units are the same units used in the ADCP software when you created the ASCII output file and are displayed in the table.
8. Once the user is happy with the 5 discharge percentages they click "Compute Stations". The table should populate the with appropriate data.

NOTE: If the cross section was from left to right distances are from the left bank but if the cross section was from right to left distances are from the right bank.

9. The discharge percentage settings can be changed the the stations recomputed without having to reload the file.