Dealing with Invalid Depths in TRDI SxS Pro

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In this video, we will discuss how to deal with invalid depths during data collection in the TRDI SxS Pro software. Note: Use of trade names is for descriptive purposes only, and does not imply endorsement by the USGS. For additional videos in this series, visit the following link: https://www2.usgs.gov/humancapital/ecd/hydrotube/hydrotube-ADCP.html
 

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Image Dimensions: 480 x 360

Date Taken:

Length: 00:02:33

Location Taken: Augusta, ME, US

Transcript

Hi, my name is Nick Stasulis and I work with the Maine Office of the New England Water Science Center.   In this video, we will discuss how to deal with invalid depths during data collection in the TRDI SxS Pro software.

There are several reasons ADCPs might not be able to get a valid depth. This could include high sediment concentrations, aquatic growth on the river bottom, large changes in depth over a short area and uneven river bottoms due to ledge or boulders, among many others. Regardless of the cause, without a valid depth the SxS Pro software will not report a velocity, and therefore a discharge. However, often, ADCPs can still measure water velocity data in places where depth can’t be determined, so if a depth is provided, the ADCP can then compute a velocity for the ensemble.

During data collection in SxS Pro there is no way of knowing specifically that invalid ensembles are due to invalid depth. Many times, you’ll notice intermittent valid data, or no valid data at all. If this is the case, there are several options for providing a manual depth for the vertical.

To be clear, you should attempt to use an appropriate ADCP and deployment method for your conditions to have the best chance of collecting valid data. If you notice a significant number of invalid ensembles, then you would use a manual depth, but not use a manual depth right from the start.

After you’ve collected a station and noticed a lot of invalid data, you could reject it and setup another vertical at that location using a manual depth, or accept the vertical and enter the manual depth in playback.

The manual depth can be determined by taking a manual sounding with a weighted line, survey rod, wading rod or other method, or can be determined using the intermittent valid ensembles. Be sure to note the method you use for determining manual depth. If channel conditions are consistent, you could also use the depth of an adjacent vertical. Once the manual depth is entered, you will notice that the number of good/bad ensembles will likely change. If the newly valid data seems reasonable based on a graphical review, it’s likely reasonable to proceed with using the manual depth. Be aware that in some cases use of the manual depth will make otherwise invalid velocity data appear valid, when it really shouldn’t be used. This makes it important to carefully review these verticals and make proper notes in SVMobile.