By Ray Valley
Aquatic Biologist and BioBase Product Expert
One of BioBase’s strengths is its simplicity. You don’t need an advanced engineering degree in hydrography to make a high quality bathymetric map with an off-the-shelf sonar device. If you have your transducer installed correctly, settings correct on your Lowrance, and achieve good coverage on your waterbody of interest, then BioBase’s EcoSound algorithm will produce a very precise, high quality bathymetric map output within minutes of upload to biobasemaps.com. The speed and ease of bathymetric mapping wins the day for many of our users, but perhaps even more valuable, is the benchmark you are setting for an unknown day in the future when something has changed on the lake and you need to have some “historical” information to understand how much change has taken place
Use Case: Monitoring Sedimentation
One of our most frequently asked questions by new users is “will BioBase measure sediment thickness or the depth of the sludge?” This was a source of a recent blog. Interestingly, the answer is different depending on how long our customers have been using BioBase. For the user who has no prior information about how deep the lake or pond is supposed to be, BioBase may not provide detailed enough information about the actual thickness of the sediment (sediment depth is correlated with EcoSound hardness but it is highly variable; see this blog for further details). However, for the pond management consultant who happened to “BioBase” a client’s pond in 2013 while she happened to be on site for another matter and is now hearing from the client in 2022 that his pond is “filling in,” the answer about whether BioBase can tell him how much sediment has filled in is a most definite yes! For this pond consultant, it was a most fortuitous (or perhaps prudent?) thing that she decided to voluntarily map her clients pond in 2013. Now with a 2022 survey, she can precisely quantify exactly how much sediment has accumulated and where over the 7 years by doing a simple subtraction of the depth and water volume between surveys and comparing maps. The comparison of maps can be done a fancy GIS way like described in this blog. Or a quick and easy way through BioBase (see examples below).
Sedimentation in Arizona’s Aqueducts – BioBase monitoring by Central Arizona Project
Delivering clean water to residences and businesses is a pretty big deal in Arizona. It’s a desert after all! The Central Arizona Project manages 336 miles of aqueducts, tunnels, and pipelines and the desert dust seems to regularly find its way into the canals and rest in the forebays where water is pumped to the next stop along the network. Since 2012, BioBase has provided a very rapid, precise, and cost-effective tool for CAP to monitor sedimentation in 15 forebays. BioBase’s polygon tool is a very quick and accurate way of determining water volume (Figures 1 and 2).
Save the polygon and inspect statistics…
I asked Central Arizona Water Conservation District (CAWCD) Senior Biologist Scott Bryan to share more about the history of monitoring these forebays and how BioBase is facilitating this important CAP program: “Prior to 2013, Central Arizona Water Conservation District (CAWCD) last conducted bathymetric survey in 2004 and 2005 to determine sediment levels in the CAP canal. Although the data gathered during this effort was valuable in determining the need for a sediment management program in the canal, the $100,000 price tag to complete the surveys in each of the 15 pumping plants was determined to be excessive and no additional surveys were completed. In 2012, I was tasked with revisiting the sediment management program. To adequately determine where sediment deposition was occurring, up-to-date surveys were necessary. I began to work with BioBase in 2012 to see if mapping using the Lowrance Chart Plotter and the cloud-based service would give an accurate representation of the sediment in the canal. A bathymetric map generated using BioBase was compared to baseline data from more expensive, time-consuming survey techniques. It was determined that BioBase matched up very closely with the baseline surveys. With that, CAWCD began an annual sediment mapping survey in 2013 utilizing BioBase. Now in it’s seventh year [as of 2018], the long-term data set has become the backbone of the sediment management program, as decisions for sediment removal are based, in large-part, on the results of the mapping efforts. In addition to the hundreds of thousands of dollars saved by utilizing BioBase over a contractor, mapping all 15 forebays takes just three days and maps are created nearly instantaneously.
See the change!
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