Mapping Hidden Channels with Genesis Live

River channel thalwegs (the line of lowest elevation within a valley or watercourse) are often dynamic, and sometimes hidden features of large river systems.  Especially low slope or impounded systems.  The thalweg is a critical geomorphological feature of river and reservoir systems and affects everything from sediment transport, to fisheries habitat, to algae or invasive plant control.

Thus a good bathymetric contour map is a necessary pre-requisite for effective river and reservoir management.  Here, we walk you through how to use new real time technologies (C-MAP’s Genesis Live) to produce smooth, precise, and accurate maps of hidden river thalwegs all within one trip to the site and with automated post-processing with BioBase’s EcoSound.  We’ll use an annotated image gallery to take you through this process.

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BioBase Paper Published: Estimation of paddlefish (Polyodon spathula Walbaum, 1792) spawning habitat availability with consumer-grade sonar.

We’re excited to see another publication demonstrating another novel use of BioBase EcoSound technology for Fisheries Science. For a complete list of pubs see hereContact us to get a copy of any of these publications

Estimation of paddlefish (Polyodon spathula Walbaum, 1792) spawning habitat availability with consumer-grade sonar
 
Jason D. Schooley
Oklahoma Department of Wildlife Conservation
 
Ben C. Neely
Kansas Department of Wildlife, Parks, and Tourism
 
Journal of Applied Icthyology 2017
 
Summary
The paddlefish (Polyodon spathula Walbaum, 1792) is a springtime migrant that requires discrete abiotic conditions such as water temperature, discharge, and substrate composition for successful spawning and recruitment. Although population declines have prevailed throughout much of the species range, Oklahoma paddlefish are abundant and support popular recreational snag fisheries – most notably in Grand Lake. This stock utilizes the Grand Lake’s two primary headwaters, the Neosho and Spring rivers, with only episodic recruitment success. However, relationships between suitable spawning habitat and water level have not been evaluated in this system. Using consumer-grade sonar equipment, this study identified and quantified hard river substrates (such as cobble and bedrock) and investigated proportional habitat availability at a variety of simulated river conditions. Sonar data were used to construct 49-m2 grids of depth and bottom hardness (H) ranging from 0.0 (soft) -0.5 (hard). Ground-truthing samples of bottom composition were collected with a grab sampler and by visual identification. Substrate types were pooled into two categories: soft substrates (H < 0.386) and spawning substrates (H ≥ 0.386) allowing for estimation of available spawning habitat in each river. Spawning habitat comprised 69% of total available habitat for the Neosho River (6.5 ha/km) and 58% for the Spring River (7.9 ha/km). Estimated spawning habitat was simulated over a range of river stages and predictive models were developed to estimate proportional spawning habitat availability (PHA). Although the Spring River contains more concentrated spawning habitat in closer proximity to Grand Lake, the Neosho River contains a greater quantity over nearly twice the distance to the first migration barrier, has a larger watershed, and demonstrates greater PHA at lower river stages. Model results were validated in context of known high and low recruitment years, where a greater frequency and duration of days with ≥90% PHA were observed in good recruitment years, particularly in the Neosho River. In total, results suggest the Neosho River has greater value for paddlefish reproduction than the Spring River. Research-informed harvest management will remain critical to the conservation of wild-recruiting stocks for continued recreational use in Oklahoma.
Average Neosho and Spring river substrate hardness index (H) for substrate classification groups across pooled methods (grab samples and visual samples). Cobble/Rock includes fine, medium, and coarse cobble pooled with bedrock. Substrates represented by H ≥ 0.386 were regarded as paddlefish spawning habitat. Sample size is noted at the base of each column and error bars indicate 95% confidence intervals
Schooley JD, Neely BC. Estimation of paddlefish (Polyodon spathula Walbaum, 1792) spawning habitat availability with consumer-grade sonar. J Appl Ichthyol. 2017;00:1–9. https://doi.org/10.1111/jai.13565

Consumer Sonar for Bottom Mapping: Updated Reference List

Another FAQ we get is wondering if there are published studies using BioBase technology? There are many legacy applications on which the BioBase technology is based. Further, now that a sufficient passage of years has accumulated to support the “research to publication” cycle, we’re happy to share several BioBase-specific studies published in the peer-reviewed literature.  This is far from an exhaustive list and we’ve intentionally left out the niche growth in consumer side-scan technology for creating habitat maps.  If there are good published papers you know of that are not on this list, please share in the comments.

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BioBase 3 Step Process: Important Details!

A primary strength of BioBase EcoSound is its simplicity and that is reflected in the easy 3 step process of “Collect,” “Upload,” and “Analyze” (Figure 1).

Figure 1. The core process of EcoSound depicting the 3 Steps of “Collect,” “Upload,” and “Analyze.”

But there are many strategies that users can employ that will ensure that they will get the best EcoSound outputs possible.  We’ll focus on several questions under each of the three categories

Continue reading “BioBase 3 Step Process: Important Details!”

Amendment to BioBase Guest Blog: GIS Tools helping CAP manage sedimentation

Earlier this year, Senior Biologist Scott Bryan from the Central Arizona Project (CAP) blogged about how the CAP is using BioBase to manage sedimentation in Arizona’s lifeblood 336-mile aqueduct.  Since then, CAP GIS Wizard Glenn Emanuel has worked some amazing magic on the BioBase grid exports using Spatial and 3D Analyst Extensions for ArcGIS (Figure 1).

Central Arizona Project, sedimentation, Lowrance, ciBioBase, BioBase, sonar, mapping, acoustics
Figure 1. Images showing the change in sediment volume prior to and after experimental dredging activities in a Forebay of the CAP canal.  The Raster Calculator in ArcGIS’s Spatial Analyst was used to subtract a “current” bathymetry from a baseline bathymetry (e.g., “as built”) to estimate sediment height and volume.  Images are 3-dimensionally enhanced using 3D Analyst for ArcGIS. Image courtesy of Scott Bryan and Glenn Emanuel, Central Arizona Project

The data and images allow CAP to make informed decisions regarding the efficiency of sediment removal operations.  In addition, ArcScene was used to produce a 3D scene of the forebay (Figure 2), which can then be animated with a video fly-through.

Central Arizona Project, sedimentation, ciBioBase, ArcScene, Lowrance, BioBase, sonar, mapping, acoustics
Figure 2. “Fly-through” images of sediment height  in Little Harquahala Forebay in the CAP Canal collected by Lowrance HDS sonar and GPS, BioBase cloud processing software, and finally exported/imported into ArcScene.  Image courtesy of Scott Bryan and Glenn Emanuel, Central Arizona Project.

Any user of BioBase properly equipped with the proper third party GIS software can create these amazing map products that are more than just pretty pictures.  They create a real-life, tangible perspective of aquatic resource conditions that BioBase users are interested in managing, protecting, and restoring.

Getting good BioBase EcoSound outputs depends on a good transducer mount!

EcoSound is a powerful and intuitive aquatic resource data processing engine that professionals across the globe are coming to recognize.  However, the quality of automated outputs greatly hinge on a proper Lowrance transducer mount.  If the transducer is off at an angle, the acoustic cone will intercept bottom at an angle and will falsely read depth, bottom composition/hardness, and vegetation height (Figure 1).

Figure 1. Example sonar log from a transducer face that is not 180 degrees with bottom as seen in Lowrance’s SonarViewer

Strategies for installing your transducer.
There are a wealth of online resources via YouTube, Google, and our own blog series (for example see our portability blog) about proper transducer mounts.  Just search “Lowrance Transducer Installation” and you’ll have a wealth of self-help resources at your disposal.  An output from a properly mounted transducer should look like Figures 2 and 3 where the bottom signal is clearly distinguishable from aquatic vegetation.

Figure 2.  Screen shot from a Lowrance HDS7 Gen2 Touch of a clear bottom signal and submerged aquatic vegetation from a properly mounted 200 kHz skimmer transducer.
Figure 3.  Example of what a clear 200 kHz signal over a vegetated bottom looks like in the EcoSound Trip Replay screen.

Often, aquatic vegetation grows to the surface of lakes and one of the unique strengths of EcoSound is that the vegetation detection algorithm recognizes conditions that appear to be surface growing vegetation and classifies the growth as such (i.e., biovolume = 100%).  Still, in order for the algorithm to function in these environments, some signal must periodically pass through the vegetation canopy and get “peaks” at bottom deeper than 2.4 ft (EcoSound minimum depth for vegetation mapping; Figure 4).  If you are mapping areas shallower than this depth, you can add manual vegetation coordinates to unmapped areas (see a CI YouTube video on how to do this)

Figure 4.  Example of a good signal in surface growing vegetation.  The bottom still tracks occasional depths of greater than 2.4 feet.  Long periods of no depth signal or depths less than 2.4 feet will result in unmapped areas and will require manually adding vegetation coordinates to your EcoSound output.

Monitor SONAR screen while you map
Because having a clear transducer signal is so critical for quality EcoSound data and map products we recommend that users verify a clear Sonar signal in an open water area prior to logging.  Drive your boat at different speeds and evaluate at what speed “slivers” start to appear in the bottom signal (Figure 5).  These slivers represent acoustic “misses” and typically result from cavitation of water around the transducer face.  Periodic slivers or misses while recording are ok, but we recommend that users monitor their SONAR page and take measures to minimize these disturbances (e.g., slow down or adjust the depth of the transducer a few inches – sometimes that’s all it takes).

Figure 5. An example of where the acoustic signal “missed” the bottom target (white slivered areas).  These misses typically result from either an improper transducer mount or excessive speed of travel that causes cavitation near the transducer face.

A Transducer Field Checklist

It might be helpful to ask these questions prior or during recording while looking at your SONAR screen and if the answer is yes to any of them, stop recording and make adjustments.
  1. Does the bottom, fish, or plant targets appear slanted?
  2. Does yellow surface clutter extend a long way into the water column and might possibly obscure vegetation target separation?
  3. Is my depth signal flashing or am I getting no digital reading?
  4. Is my range window jumping around indicating it can’t find depth?
  5. Am I getting a lot of white slivers in my bottom reading?
Editing your EcoSound output

If bad signal does sneak past your scrutinizing eyes, fear not, you can always edit your output with EcoSound’s Trip Replay feature as seen in our YouTube video series.

By installing your transducer correctly and monitoring your output you’re almost guaranteed a quality map of lake, river, or coastal habitats with EcoSound.  Contact us at info.biobase@c-map.com to learn more. 

Guest Blog: Using BioBase to determine sedimentation in the Central Arizona Project canal

by Scott Bryan

The Central Arizona Project (CAP) is a multipurpose water resource development and management project that provides irrigation, municipal and industrial water to much of Arizona.  The primary means of water conveyance is a 336-mile concrete-lined aqueduct that transports water from the Colorado River, on Arizona’s western border, across the State to Phoenix, and then southward to the aqueduct terminus near Tucson.  Each year, over 1.5 million acre-feet of water is delivered to our customers.

Since its completion in 1993, the aqueduct system has experienced increasingly severe sedimentation that creates problems within the pumping plants and in the aqueduct itself.  Because the sediments can decrease the flow capacity of the aqueduct, cause damage to pumps and internal systems, and restrict flow through critical filtration units, it is imperative that dredging operations occur periodically.

sedimentation, ciBioBase, water volume, depth, mapping, bathymetry
CAP forebay dredging in 2009

In the past, CAP performed intensive sonar based sediment studies to determine bathymetry and the amount of deposition in the forebay of each of the 13 pumping plants.  The surveys show when and where dredging operations should occur.  These surveys were contracted to outside companies with costs ranging from $40,000 to $120,000 annually.

In 2012, CAP began to use the sonar technology provided by BioBase to conduct its own bathymetry surveys in the pumping plant forebays.  Water depths are compared to historical baseline surveys and the volume of sediment in each forebay can easily be calculated.  Annual surveys allow us to compare sedimentation from year-to-year to determine loading rates and critical areas to target sediment removal.  Surveys of all 13 forebays can now be accomplished in three days rather than six months, and when compared to the expensive surveys from the past, are equally as accurate.

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Blue-scale bathymetric map of a CAP forebay.  The light blue contours show an area that is extremely shallow and is in need of sediment removal.

 

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Example transect design and resultant bathymetric map coupled with the sonar log viewer.  Notice the detailed image of the forebay’s trash racks produced by Lowrance HDS DownScan
This new approach to bathymetric and sedimentation mapping saves time and money, allows us to evaluate results immediately, and makes dredging operations more efficient and timely.

Scott Bryan is the Senior Biologist for Central Arizona Project (CAP).  After receiving an M.S. in Fisheries Management at South Dakota State University, Scott worked as a research biologist for Arizona Game and Fish for 10 years, then specialized in lake and stream management for seven years at a private consulting firm in Albuquerque.  Scott’s current position at CAP includes a broad scope of work, including aquatic and terrestrial vegetation control, fisheries and wildlife management, invasive species research, and water quality monitoring.