Application of Sonar Depth Finder in Lagoon Sludge Survey – Livestock and Poultry Environmental Learning Community

Purpose

Regular monitoring of lagoon depths is crucial for effective manure management and environmental compliance. Traditional methods, using a disc on a rope or a marked stick from a boat can be time-consuming and pose safety risks, especially in larger or deeper lagoons. This study aimed to determine the feasibility of using low-cost sonar depth finders for lagoon sludge measurement.

What Did We Do?

Depth measurements were conducted by using sonar devices and compared with traditional methods at a 2.5-acre dairy lagoon that received effluent from a pull-plug sediment basin. The sonar devices, along with a cell phone (data logger) were mounted on an air-filled float and dragged across lagoon surface, enabling measurements without the need for a boat.

Fig. 1. Lagoon depth measurement was conducted using a small kayak (left); practical and simple lagoon depth measurement by dragging air-filled float with sonar ball and cellphone (as data logger) across lagoon surface (right).

Fig. 2. Field measurement points on the lagoon surface for the liquid depth measurement using disc on a rope and a sonar ball sensor. The white dots are measurement points to compare sonar ball method and disc on a rope method, the blue lines were measurement paths dragging a small air-filled float carrying sonar ball

What Have We Learned?

Fig. 3. Liquid depth measurement devices applied: disk on a rope (left), wood stick with depth markings (middle), and two types of commercial sonar balls (right).

Fig. 4. Comparison of depth measurements using different measurement methods.

The disc on a rope (standard) and wood stick method resulted in similar values. Meanwhile, the sonar balls tend to slightly underestimate depth, with a margin of error below 15%, while the errors were higher for very shallow areas.

Fig. 5. Linear regression of depths, comparing the Deeper Sonar PRO+ and Deeper Fishfinder START, with disc on a rope values.

Linear regression models revealed strong correlations between sonar readings and the disc-on-a-rope method, with R² values of 0.899 for the PRO+ model, and 0.9377 for the START model. Applying a correction model to the sonar data could further enhance the measurement accuracy. This study demonstrated that integrating sonar measurements with periodic sludge sampling provides a practical, safe, and reliable approach to improving lagoon management.

Authors

Presenting author

Moh Moh Thant Zin, Post-doctoral researcher, University of Missouri-Columbia

Corresponding author

Teng-Teeh Lim, Extension Professor, University of Missouri-Columbia, limt@missouri.edu

Additional author(s)

Zonggang Li, Gilbert Mitto, Manobendro Sarker, Rana Das, Cuong Duong, University of Missouri-Columbia.

Acknowledgements

This research was supported by USDA-NIFA, grant award (# 2018-68011-28691), and University of Missouri Extension.

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