BioBase Paper Published: Accuracy and Precision of Low-Cost Echosounder and Automated Data Processing Software for Habitat Mapping in a Large River

We are grateful to the aquatic research community who continue to verify and validate Consumer Sonar Technologies (Lowrance) and BioBase automated mapping platform to produce scientifically valid outputs that benefit aquatic conservation.  We are excited to see the recent publication of research out of the University of New Brunswick that evaluated the accuracy and precision of Lowrance and BioBase’s EcoSound depth and vegetation outputs.  The research is published in the open access journal Diversity and can be downloaded here. Below is the abstract

Abstract
The development of consumer hydroacoustic systems continues to advance, enabling the use of low-cost methods for professional mapping purposes. Information describing habitat characteristics produced with a combination of low-cost commercial echosounder (Lowrance HDS) and a cloud-based automated data processing tool (BioBase EcoSound) was tested. The combination frequently underestimated water depth, with a mean absolute error of 0.17 ± 0.13 m (avg ± 1SD). The average EcoSound bottom hardness value was high (0.37–0.5) for all the substrate types found in the study area and could not be used to differentiate between the substrate size classes that varied from silt to bedrock. Overall, the bottom hardness value is not informative in an alluvial river bed setting where the majority of the substrate is composed of hard sands, gravels, and stones. EcoSound separated vegetation presence/absence with 85–100% accuracy and assigned vegetation height (EcoSound biovolume) correctly in 55% of instances but often overestimated it in other instances. It was most accurate when the vegetation canopy was ≤25% or >75% of the water column. Overall, as a low-cost, easy-to-use application EcoSound offers rapid data collection and allows users with no specialized skill requirements to make more detailed bathymetry and vegetation maps than those typically available for many rivers, lakes, and estuaries.

EcoSound vs Manual Measures Vegetation Helminen et al 2019

Networking 3rd Party GPS/GNSS into Lowrance

Ray Valley

Aquatic Biologist and BioBase Product Expert

I frequently get inquiries from current and prospective BioBase users about the accuracy of consumer-grade Lowrance GPS and whether survey-grade 3rd party receivers capable of differential correction (DGPS) or receiving positions from multiple satellite constellations (Global Navigation Satellite System – GNSS) could be used with Lowrance and processed with BioBase.

The first question about accuracy prompted a test in March of 2013 with a Lowrance HDS tested side-by-side with a Trimble GeoXH.  I was pleased to find less than 1m deviation on average from post-processed Trimble DGPS positions.  One meter accuracy and precision is typically sufficient for most boat-based mapping applications. Still, prerequisites for some projects require DGPS, and there are a number of BioBase users who have and still would prefer to have DGPS generated positions to use when logging trips. Thus, I was interested in exploring the capabilities of networking positions from a third-party receiver into a Lowrance HDS.

Continue reading “Networking 3rd Party GPS/GNSS into Lowrance”

BioBase Project Propels Jeff Schuckman to Nebraska Game and Parks Employee of the Year!

Lake Yankton, a 332-acre backwater lake on the Nebraska/South Dakota border had a problem. In the summer of 2011, the Missouri River flooded, spilling into the lake a number of undesirable invasive rough fish, including large numbers of carp (silver, bighead, grass, and common), smallmouth buffalo, and gizzard shad. Notorious for stirring up lake bottoms while feeding and spawning — and for overeating zooplankton and aquatic plants — these species degrade water quality and fisheries.  

Overrun by these invasive species, Lake Yankton soon looked like chocolate milk, with a water clarity of only three inches — that’s right, inches, not feet.  So the cavalry was called in to assess the situation and provide a solution. Leading the effort was Nebraska Game and Parks Commission District Fisheries Manager Jeff Schuckman.

Fortunately for Nebraska anglers, this wasn’t Schuckman’s first rodeo. He knew the lake could be rehabilitated with careful application of Rotenone, a common fish-killing chemical. The challenge would be to determine just how much of the chemical was needed, and then purchase and apply just enough to do the job — no more, no less.

Continue reading “BioBase Project Propels Jeff Schuckman to Nebraska Game and Parks Employee of the Year!”

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.

Mapping Ponds with BioBase

As an addendum to our blog series on rapid, portable applications we wanted to experiment with a “thru-hull” mount of the 83/200 khz Lowrance HDS transducer on a kayak for mapping storm water retention ponds in an urban area of Minnesota (City of Maple Grove).  Electrician putty (sold as “Duct Seal”) available for a few dollars at the neighborhood hardware store worked as a perfect medium for this application.  Follow the series of pictures and captions to see how this worked!

Electrician putty or “Duct Seal” available at most hardware stores can be used for shoot “thru-hull’ applications on kayaks or canoes

 

Figure 2. A 83/200 Lowrance skimmer transducer secured to the hull of a polyethylene kayak by duct seal putty. Care should be taken to remove all air bubbles from the mold before pressing in the transducer
James Johnson from Freshwater Scientific Services LLC gets his Lowrance HDS-5 all set to log data.
Tracks showing a concentric circle approach toward mapping ponds smaller than 10 acres.  This one is 3 acres located in an urban area of Minnesota near Minneapolis (Maple Grove).  Data took 30-min to collect
Blue-scale bathymetric output created after 10-minutes of data processing time by BioBase servers after upload.  Map was produced by 1,000 passively acquired GPS and bottom points.  All map outputs (e.g., water volume or hardness – next picture) can be analyzed in your private BioBase online account or exported to GIS for more sophisticated data analyses and layering
Bottom hardness automated output automatically created along with bathymetric and aquatic vegetation layers  in BioBase.  Areas that are maroon represent hard areas that remained from the original construction of the pond.  Soft areas are represented by the lighter brown colors and represent sand deltas from parking lot runoff.  Hardness and bathymetric outputs can be used to assess whether storm water retention ponds require maintenance and where specifically to focus efforts

 

Lowrance GPS Accuracy: Seeing is believing!

A quick post to demonstrate the precision of Lowrance’s internal WAAS corrected GPS antennae is in a variety of open water environments.  Docks? Boat lifts? Overhanging trees?  No problem.  WAAS correction in North America is explained here.  Have a look at a couple examples in ciBioBase:

GPS Track from a Lowrance HDS on Newport Bay, California overlain onto a bathymetry map created by automated processing of the Lowrance .sl2 log file by ciBioBase.  This trip was used for water volume calculations, bathymetry, and vegetation mapping

GPS tracks and ciBioBase derived bathymetry map in a 3-acre pond in a wooded valley in a metropolitan area of Minnesota, an example of retention pond volume monitoring.

GPS tracks and ciBioBase derived contour map of a 3-acre pond in Illinois for water
volume and aquatic vegetation analysis

GPS tracks around docks and boat lifts and ciBioBase derived contour map on Grand Lake O the Cherokees near Tulsa  Oklahoma.  The satellite even shows data collection in an area where a boat can be moored next to the dock.  That’s close!

Lake Bottom Depth Precision and Accuracy

In an addendum to an earlier post, we continue to evaluate the accuracy and precision of BioBase depth outputs.  Lowrance has been in the depth sounding business since 1957.  They have tight factory calibration standards whereby depth should never be more than 2% different than the actual depth.  Of course then we expect depths to be spot on on hard bottom surfaces where truth can be easily measured.  But what about in mucky bottoms which are common place in many lakes, ponds, backwaters throughout the US and abroad?  With this in mind, in late May of 2012, we traveled to Pool 8 of the Mississippi River near LaCrosse WI to do some testing in a mucky, moderately dense vegetated backwater (Figure 1).  At some point we have to step back and ask, “what is the bottom of a body of water?”

Figure 1.  Vegetation cover and biovolume (% of water column occupied with vegetation) in Pool 8 of the Mississippi R. in LaCrosse WI on 5/29/2012.  Average biovolume was 30% during the survey.

The most difficult aspect of this testing was to get an objective estimate of the true depth.  In other words, where exactly did the plants end and bottom start?  Typically, investigators use a survey rod like that seen in Figure 2 to estimate actual bottom based on where they feel resistance on the survey rod.  Piece of cake over sand.  Not so easy over flocculant silt and muck or vegetative areas.

Figure 2.  Measuring bottom with a survey rod in a mucky Minnesota Lake.  Typically, the survey rod will sink several inches into the bottom before the surveyor feels resistance and judges the depth to the bottom

Many experienced surveyors will tell you that the rod will sink into the muck some distance before you feel resistance.  There is a positive correlation in the distance it sinks and how mucky the bottom is.  So, we went into this investigation expecting deeper rod depths measured than ciBioBase outputs. 

Accurate and precise results in mucky, vegetated bottoms

After 30 points measured with the survey rod, we compared the results with the ciBioBase depths measured in the same location.  We were pleased to see very high precision with a Coefficient of Determination (R^2) of 0.94 and a systematic difference in depth of only 4.9″ (Figure 3).  The depth of 4.9″ was quite possibly the average depth where we first felt resistance of the survey rod.  The upshot here is that ciBioBase depth outputs are highly precise, consistent and accurate even in mucky vegetated bottoms.

Figure 3. Accuracy and precision of ciBioBase depths measured against depths collected with a survey rod in the mucky, vegetated backwaters of Pool 8 of the Mississippi River near LaCrosse, WI.

Bathymetry Mapping with ciBioBase!

At Contour Innovations, we often preach the importance of aquatic plant mapping and monitoring, but of equal importance and capability is ciBioBase bathymetric mapping features.  ciBioBase comes with many features that automate the tedious, mundane, yet highly technical GIS processes associated with creating a bathymetric map.  Water resource and lake managers and researchers should be spending their time and talents focusing on thorny management problems, not compiling and managing volumes of data and trying to map them in GIS.  The science of acoustic bottom detection and GIS mapping has been extensively tested, verified, and proven with standard methods.  We automate this.

Because ciBioBase maps only areas you cover up to a 25-m buffer outside of your track, you are assured that maps do not include extrapolated data.  40-m spacing of transects with a criss-cross design assures you that you will get complete coverage and smooth contours (Figure 1). 

Figure 1. Transect coverage showing a “criss-cross” design to assure a high quality bathymetric map.

The Trip Replay feature in ciBioBase further allows you to see disruptions in the contours (Figure 2).  As in the case with Figure 2, there was a temporary disruption in the transducer signal, thus giving an erroneous depth (Figure 2 and 3).  In ciBioBase, these erroneous depths can be edited out; thus creating a smoother, more accurate bathymetric map and associated statistics.

Figure 2. Desktop verification of bathymetric outputs with ciBioBase’s Trip Replay feature.
Figure 3. Areas of disrupted signal can be deleted and the trip reprocessed for a more accurate and smooth bathymetric map.

Other times, these little “donuts” occur because depths temporarily enter a different contour level (e.g., 3ft contours with series depths = 5.99, 6.0, 5.99, 5.98, etc).  Although the 6.0 depth is likely legit, it may be more aesthetically pleasing to remove the 6.0 depth to prevent the creation of a 6ft donut hole.

Once you are happy with the output with individual trips, you can merge them in ciBioBase to create a uniform output (Figure 4).

Figure 4.  Merging function in ciBioBase that allows users to merge individual files or trips into a single, uniform map.

Tying Bathymetry to a Benchmark Elevation
When mapping bathymetry, it may be important to tie the water level to a benchmark water level elevation.  In our Minnesota Lake example, we went to the Minnesota Department of Natural Resource’s Lakefinder website and found important water level information (Figure 5).  On 6/5/2012, we surveyed McCarron’s Lake in Ramsey County, MN.  On 6/7/2012, the elevation-corrected water level reported by citizen volunteers was  840.84 ft above sea level.  The Ordinary High Water Level  (OHW) benchmark for McCarron’s is 842.21 ft (Figure 5).  Using the Data Offset feature in ciBioBase (Figure 6), we can simply add 1.37 ft (elevation correction) plus 1 ft (transducer correction) to get a bathymetric map that is corrected to the OHW (Figure 7).  This eliminates water level as a confounding variable with repeated bathymetric surveys on the same waterbody.  The final products are high resolution, blue-scale imagery as seen in Figure 7 (up to 1-ft contours) or the actual point and grid data that can be imported into any third party GIS or statistical software (Figure 8).

Figure 5. Water level information for McCarron’s Lake in Ramsey County, Minnesota USA.
Figure 6. Data Offset feature in ciBioBase that allows users to correct their bathymetric data to a benchmark water level and transducer depth.
Figure 7. Bathymetric imagery with resolution (both bottom and pixel) that can be controlled by the user.
Figure 8. Export point data along your traveled path or the kriging interpolated grid for use in third party GIS or statistical software.

Life is good in the cloud…

Because of the centralized, cloud-based platform of ciBioBase, we see trip uploads into the system from all types of lakes, ponds, and reservoirs throughout the country and even abroad; so our acoustic and geostatistic algorithms have seen it all!

See for yourself in our demo account at ciBioBase.com.  In the login page, enter demo@cibiobase.com and “demo” for the password.  Operators are standing by to answer any questions you may have!