Single Beam Echosounder Research Articles

Mapping American lobster (Homarus americanus) habitat for use in marine spatial planning

Marine spatial planning (MSP) is a management tool that could help mitigate the conflict that exists between the American lobster (Homarus americanus) fishery and the net-pen salmon aquaculture industry in the Canadian Maritime provinces. We developed adult American lobster species distribution models (SDMs) for use in MSP in Liverpool, Nova Scotia, through remote sensing data collection methods. A single-beam echo sounder was used to collect bathymetry and seafloor substrate data, and an aerial drone collected lobster presence data through the georeferenced photography of lobster trap buoys. The SDMs display trends in lobster presence likelihood that correspond with established patterns of habitat selection in adult lobsters. The areas where lobsters are predicted to have the highest likelihood of presence are sections of hard and rocky substrate, though that association is confounded by depth. The uncertainty of the SDMs was quantitatively assessed and the importance of explicitly analysing the effects of scale and resolution of spatial data are highlighted.

Detection Method for Single-Beam Echo Sounder Based on Equivalent Measurement

Acoustic instruments like the single-beam echo sounder are basic tools for marine scientific research; consequently, the effective detection and calibration of the equipment are crucial to ensure the quality of marine data. Considering that the detection of full-range precision index of a single-beam echo sounder cannot be carried out in a laboratory sink, this paper proposes a new detection method based on equivalent measurement. In an anechoic environment, a circuit is used to simulate the long-distance propagation of the sound wave. The full-range equivalent measurement of the single-beam echo sounder is realized within the limited range of the laboratory sink. Experimental verification proves that the proposed method is feasible and provides a new technical approach for the detection of marine acoustic instruments.

Development of a Highly Portable Unmanned Surface Vehicle for Surf Zone Bathymetric Surveying

Francis, H. and Traykovski, P., 2021. Development of a highly portable unmanned surface vehicle for surf zone bathymetric surveying. Journal of Coastal Research, 37(5), 933–945. Coconut Creek (Florida), ISSN 0749-0208. This study reviews the design and subsequent effectiveness of a prototype autonomous survey vehicle built to collect data specifically in the surf zone. The breaking wave transitional zone between ocean and land is an important location to survey due to its impact on human infrastructure and vulnerability to the effects of climate change. However, this environment is notoriously difficult to survey due to its shallow depth and the turbulence of waves and currents. Three distinctive design choices were made at the beginning of the project with the goal of operating in the surf zone: First, the surface vehicle is light (15 kg) and fast (up to 7 m/s), both characteristics intended to enable one person to deploy it quickly and easily into the surf zone. Second, an electric motor that is connected to a jet drive eliminates a combustion engine's air intake, which can be contaminated with seawater and sand. The jet drive also removes any danger of spinning propellers and allows the vessel to run in very shallow water. Finally, the vessel has a foam bulb hatch cover that is watertight and allows the vessel to right itself if capsized by a wave. The outcome of this development effort is an unmanned vessel that has the maneuverability and power sufficient for surf zone operations and is self-righting. It runs off the waypoint based Ardupilot Mavlink program, which allows rapid transitions from autonomous modes to remote controlled modes and has a runtime of approximately 1.5 hours. The vessel has initially been used with a single beam echosounder and precision GPS to create highly detailed shallow water bathymetric maps. This study demonstrates this technique as a highly efficient method of creating bathymetric maps in coastal environments.

Integration of Satellite-Derived Bathymetry and Sounding Data in Providing Continuous and Detailed Bathymetric Information

A hydrographic survey can be a cumbersome sometimes. The data can be sparse, providing it can be costly, and it took a lot of manpower and time. Space-borne data like multispectral images can be a helpful tool towards hydrographic survey, especially in the shallow water area. The company like EOMAP and TCARTA make use of Satellite-Derived Bathymetry (SDB) as a tool and product. Would it be great if it also can be applied in Malaysia, especially on the low-risk job or survey planning? Enlarging the survey area and providing a continuous and detailed water depth information is the main objective in this research. In order to complement with convenience and cost reduction, the author used Landsat 8 “(free downloadable images)” in this research. Structuring the procedure is the central part of the process involving pre-processing and processing step until the final product obtained. In this research, the author used various kind of bathymetry algorithms such as Single-Band Algorithm (SBA), Green-Band Algorithm (GBA), and Stumpf. Moreover, the author also uses Principal Component Analysis (PCA) tool from ArcMap and Spear Relative Water Depth: Log-Ratio Transform tool from ENVI to derived bathymetry. All of this bathymetry algorithm gives out a different concept with a different statistical approach. The final result then will be compared and evaluated with Single-Beam Echosounder data (ground truth).

Characterization of seafloor roughness from high-frequency acoustic backscattering measurements in shallow water off the west coast of India.

Measurements of the reverberation time series are made at frequencies of 8, 10, and 12 kHz, and the corresponding acoustic bottom backscattering strengths are estimated as functions of grazing angle. The experiment was conducted in the western continental shelf of India (off Kerala) in water depth of ∼61 m where hard sandy sediments of biogenic origin are predominant. The average values of two-dimensional (2D) spectral strength (w2) and exponent (γ2) of seafloor roughness are obtained by inverting bottom backscattering strength data with the help of a scattering model, utilizing the genetic algorithm method. Measurements of one-dimensional interface roughness height are also carried out using a single beam echosounder to analyze the variability of bottom roughness in terms of spatial frequency. The spectral parameters estimated from roughness height measurements are compared to that obtained from inversion results. The 2D spectral strength and exponent of seafloor roughness estimated from the two methods agree with each other and are consistent with the typical values associated with sandy sediments.

Research on detection method of single-beam echo sounder based on equivalent measurement

In order to detect the accuracy index of the full range of the single-beam echo sounder in the laboratory sink, a detection method based on the equivalent reflection interface of the acoustic signal is proposed. A set of measurement and detection device consisting of underwater acoustic response device, laser rangefinder (standard device) and five-sided muffler pool is also designed. The acoustic signal equivalent interface adopts a DSP-based circuit design. By equivalent simulating a long-distance echo signal with the delay and attenuation of the electrical signal, different equivalent depths are constructed in the anechoic environment. Finally, a data traceability system for a single- beam echo sounder can be established through correspondence formula derivation and data analysis.

Bathymetric Monitoring of Alluvial River Bottom Changes for Purposes of Stability of Water Power Plant Structure with a New Methodology for River Bottom Hazard Mapping (Wloclawek, Poland).

The aim of this research was to produce a new methodology for a special river bottom hazard mapping for the stability purposes of the biggest Polish water power plant: Włocławek. During the operation period of the water power plant, an engineering-geological issue in the form of pothole formation on the Wisła River bed in the gravel-sand alluvium was observed. This was caused by increased fluvial erosion resulting from a reduced water level behind the power plant, along with frequent changes in the water flow rates and water levels caused by the varying technological and economic operation needs of the power plant. Data for the research were obtained by way of a 4-year geodetic/bathymetric monitoring of the river bed implemented using integrated GNSS (Global Navigation Satellite System), RTS (Robotized Total Station) and SBES (Single Beam Echo Sounder) methods. The result is a customized river bottom hazard map which takes into account a high, medium, and low risk levels of the potholes for the water power plant structure. This map was used to redevelop the river bed by filling. The findings show that high hazard is related to 5% of potholes (capacity of 4308 m3), medium with 38% of potholes (capacity of 36,455 m3), and low hazard with 57% of potholes (capacity of 54,396 m3). Since the construction of the dam, changes due to erosion identified by the monitoring have concerned approximately 405,252 m3 of the bottom, which corresponds to 130 Olympic-size pools. This implies enormous changes, while a possible solution could be the construction of additional cascades on the Wisła River.

Port Bathymetry Mapping Using Support Vector Machine Technique and Sentinel-2 Satellite Imagery

Knowledge of the free draft of ports is essential for the adequate management of ports. To maintain these drafts, it is necessary to carry out dredging periodically, and to conduct bathymetries using traditional techniques, such as echo sounding. However, an echo sounder is very expensive and its accuracy is subject to weather conditions. Thus, the use of recent advancements in remote sensing techniques provide a better solution for mapping and estimating the evolution of the seabed in these areas. This paper presents a cost-effective and practical method for estimating satellite-derived bathymetry for highly polluted and turbid waters at two different ports in the cities of Luarca and Candás in the Principality of Asturias (Spain). The method involves the use of the support vector machine (SVM) technique and open Sentinel-2 satellite imagery, which the European Space Agency has supplied. Models were compared to the bathymetries that were obtained from the in situ data collected by a single beam echo sounder that the Port Service of the Principality of Asturias provided. The most accurate values of the training and testing dataset in Candás, were R2 = 0.911 and RMSE = 0.3694 m, and R2 = 0.8553 and RMSE = 0.4370 m, respectively. The accuracies of the training and testing dataset values in Luarca were R2 = 0.976 and RMSE = 0.4409 m, and R2 = 0.9731 and RMSE = 0.4640 m, respectively. The regression analysis results of the training and testing dataset were consistent. The approaches that have been developed in this work may be included in the monitoring of future dredging activities in ports, especially where the water is polluted, muddy and highly turbid.

Model approaches for the classification of sediment

The paper explores two model approaches to the single-beam echosounder classification of sediments. Their applications for the analysis of oceanographic data are shown.

DISTRIBUTION AND DENSITY OF DEMERSAL FISHES IN YOUTEFA BAY, PAPUA, INDONESIA: A STUDY USING HYDROACOUSTIC TECHNOLOGY

A study was conducted to estimate the distribution and density of demersal fish in Youtefa Bay, Papua, Indonesia, using hydroacoustic technology. The hydroacoustic survey was carried out using a single beam echosounder SIMRAD EK-15 which operates at a frequency of 200 kHz. The hydroacoustic data was processed using Echoview software with a threshold between -70.00 to -34.00 dB. Schooling fish were detected at a maximum distance of 3 m from the seabed, with average volume backscattering strength ranging between -60.13 and -42.01 dB. The demersal fish density in the Youtefa Bay ranged from 0.09 to 42.19 fish m-3 with an average density of 12.62 fish m-3. The schools of demersal fish were dominantly detected in the coastal waters of Enggros Village to Abe Pantai Village. The condition of substrate and water depth seems to influence the spatial and vertical distribution of demersal fish in the Youtefa Bay.

Bathymetry and Seabed Morphology Study for Determination of ASDP Shipping Line in Tanjungsau Island Waters, Batam

Tanjungsau Island Waters as the main gate of shipping line between Bintan Island and Batam need more attention for its shipping safety. The purpose of this research is to review the seabed morphology of Tanjungsau Island Waters, Batam for determination of ASDP shipping line. This research had been conducting from 3rd to 5th of Jule 2018 in The Tanjungsau Island Waters, Batam. The used data are depth measurement by singlebeam echosounder type Ceducer Pro, tidal data, ship draft, and Digital Map of Indonesia Sea edition 2013 Vol. 49 published by TNI-AL DISHIDROS. Data had processed by using ArcGIS 10.3 and Surfer 9 software to generate the bathymetry contour and the 3D model of seabed morphology. The result indicates that the depth ranged between -1,69 m to -17,58 m. The bathymetry contour map shows seabed morphology is a continental shelf. Based on the slope calculation, Tanjungsau Island Waters not only include flat category between 1,08% - 1,58% but also having a slope area worth 2,59%. The right ASDP shipping line from Bintan Island to Batam has the minimum depth -5,32 m with the largest ship draft which can enter approximately 4,788 m.

A multi-frequency acoustic method to estimate mean standard length of juvenile salmon in the Discovery Islands, British Columbia

A method to estimate the mean standard length (L¯) of juvenile salmon in aggregations using multi-frequency (67 and 125 kHz) acoustic analysis was developed. An autonomous, single beam echosounder (Acoustic Zooplankton and Fish Profiler (AZFP), ASL Environmental Sciences) was deployed on the seafloor in Okisollo Channel, British Columbia during peak juvenile salmon migration season in 2015 and 2016. A positive correlation was found between the difference in the mean volume backscattering strength at 67 and 125 kHz (ΔMVBS67-125kHz) of juvenile salmon aggregations and the mean standard length of juvenile salmon collected with a purse seiner. A relationship of the form ΔMVBS67-125kHz=Alog10L¯+B was established. High variability was observed due to differences in salmon species composition and lower sampling sizes at the tail end of the migration periods, but a consistent relationship with comparable parameters was found. We suggest that this method is valuable particularly in the case of long-term monitoring of species that are known to aggregate in schools of individuals with similar size, as it can be used to estimate mean size without the use of invasive capture techniques.

PlanetScope and Landsat 8 Imageries for Bathymetry Mapping

Bathymetry has a great importance in coastal projects. Obtaining proper bathymetric information is necessary for navigation, numerical modeling, and coastal zone management studies. Over the past three decades, a number of measuring protocols have been validated for bathymetry mapping, either by means of echosounding or LIght Detection and Ranging (LIDAR). Although these traditional methods hold a high vertical accuracy, they may have limitations in accessibility for some areas. Remote sensing (RS) techniques can be alternatively utilized for bathymetry extraction and update for such cases. The satellite derived bathymetry (SDB) can be analytically or empirically obtained based on various RS datasets with different spatiotemporal resolution. The current study proposes a methodology to spatially enhance the Landsat-derived bathymetry. Two different satellite images, i.e., Landsat and PlantScope with a spatial resolution of 30 and 3 m respectively have been assessed in bathymetry mapping. The Landsat image resolution has been spatially enhanced to match the Planetscope resolution. The panchromatic band of the Landsat image has been downscaled and used for pan-sharpening the multispectral bands. The bathymetry was empirically estimated from the blue and green spectral bands using the linear model by Lyzenga. The SDB model was calibrated using field measurements of water depths observed by a single beam echosounder. The Bathymetry detection methodology has been applied in an area of the Northern coast of Egypt. The SDB from the PlanetScope, Landsat 8 OLI, and Enhanced Landsat 8 OLI were assessed using error analysis. It was found that the Enhanced Landsat has a comparable result with the PlanetScope. The root mean square error is 0.38 and 0.43 m for PlanetScope and Enhanced Landsat, respectively. The current methodology was also tested by the ratio transform model for SDB and the results revealed the same conclusion as the linear model. Thus, the developed algorithm provides SDB using free Landsat images that is of comparable accuracy to the relatively expensive PlanetScope SDB.

Targets strength of freshwater fish with single beam echosounder

Cyprinu scarpio, Oreochromis niloticus, Pangasius, Anguilla sp, Ospronemus goramy and Serrasalmus sp are the types of fresh fish consumed widely by Indonesian society. Each type of fish has different acoustic backscatter strength influenced by meat, swim bladder and fish behavior at the time of data collection. This acoustic backscatter value has a decibel unit (dB). The purpose of this research is to get the value of single fish acoustic backscatter from those species. Data was recorded using single beam equipment frequency 200 kHz (cruzpro and Simrad EK-15 echosounder equipment). The results show the TS value of the six fish varies between -53 dB to -41dB. The TS relationship with length has a correlation coefficient value (R) greater than 0.5, which means that fish length has contribution more than 50%. Data was observed in a July 2015 trial using the same equipment and software. It was found that fish with the same length, which is 19 cm of different species (C. carpio, Pangasius and O. niloticus) but had different weights, turned out to have the different TS values. It is assumed that the characteristics of each fish body are different.

Kehadiran Gelombang Soliter dan Transpor Sesaat Sedimen tersuspensi di Perairan Pantai Bengkulu Tengah

<strong>Existence of Solitary Waves and Transient Suspended Sediment Transport in the Coastal Waters of Central Bengkulu. </strong>Coastal abrasion and suspended sediment transport driven by waves is occurring dreadfully in the coastal waters of Central Bengkulu. The abrasion tends to be accelerated by solitary waves during the southeast monsoon season. The primary data were obtained on 17-26 July 2014, while the secondary data derived from Google Maps imageries obtained on 17 June 2014, representing the southeast monsoon season. The primary data were collected by 1200 KHz Acoustic Doppler Current Profiler (ADCP) for water currents, a single beam Echosounder for depths, Garmin 276C GPS receiver for coordinate positions, RBR-TWR2050 (installed at at a fixed point at 102.2219 °E and 3.6916 °S and depth of 9 m) for height and wave periods, and a compass for the direction of wave propagation. The secondary data included Astrium satellite imageries compiled by Google Earth and displayed as Google Maps images on 17 June 2014. These images were used for identifying the appearance of wave groups and by using a feature in Google Earth, it showed that the estimated distance between wave packets hitting the coast accounted for 147 m. This study showed the existence of solitary waves with height and wave period of 1.02 m and 13.85 seconds respectively, while the wave length reached 147.7 m. The wave energy and wave energy flux were 1123.12 Jm<sup>-2</sup> and 12018.94 Jm<sup>-1</sup>s<sup>-1</sup>, calculated by using the cnoidal wave theory and solved by the KdV equation. These solitary waves have large destructive forces on unstable cliffs along the coasts. Derived from coastal abrasion processes and shown by the ADCP backscatter intensity with the highest of 146 dB, the suspended sediments were likely to be transported by water currents with an average speed of 25.99 cm s<sup>-1</sup> in the dominant direction to the south - southeast; and the sediments were deposited along the coast of Bengkulu City.

Detection of bottom substrate type using single-beam echo sounder backscatter: a case study in the east coastal of Banyuasin

This research was aimed to identify substrates type in the east part of the Banyuasin coastal waters using quantitative backscatter data from single-beam echo-sounding. The SIMRAD EK-15 was used to classify the seafloor substrate types. The ground truth was required for calibrating the acoustic result. Wet sieving methods and Shepard’s triangular diagram were used to analyze the ground truth samples. The acoustic data were filtered to extract the volume backscattering strength of bottom surface (SV) using Echoview 4.0. The data of bottom surface backscattering strength (SS) and SV were classified by using Hierarchical Cluster Method. Data of substrate type from the ground truth will be used as a guideline to classify the SS data to identify the substrate type based on the SS characteristic which associated with various types of the bottom substrate. The results showed the single beam capability in distinguishing the types of bottom substrate, namely clayed sand with the SS value ranges from -47.29 to -46.32 dB), silt + sand + clay with the SS value ranges from -51.00 to -48.54 dB), clayed silt with the SS value ranges from -53.47 to -52.24 dB), and silty clay with the SS value ranges from -56.89 to -55.94 dB.

Automated Estimation of Coastal Bathymetry from High Resolution Multi-Spectral Satellite Images

Coastal bathymetry is the most essential tool for marine planning, monitoring and management, modelling, nautical navigation and scientific studies of marine environments. The techniques have been developed over the last decade to derive bathymetry using remote sensing technology with efficiently and low costly. Log linear bathymetric inversion model and non-linear bathymetric inversion model provides two empirical approaches for deriving bathymetry from multispectral satellite imagery, which have been refined and widely applied. This paper compares these two approaches by means of a geographical error analysis for the site Kankesanturai using WorldView-2 satellite imagery. In order to calibrate both models; Single Beam Echo Sounding (SBES) data in this study area were used as reference points. Corrections for atmospheric and sun-glint effects are applied prior to the water depth algorithm. The algorithm was tuned and both models were calibrated by performing the necessary algorithm with available single beam echo sounding data in the study area. The coefficients of standard R2 is estimated as 0.846 for log-linear and 0.692 for non-linear model. Log linear model performs better than the non-linear model. The model residuals were mapped and the spatial auto-correlation was calculated based on the bathymetric estimation model. A spatial error model was constructed to generate more reliable estimates of bathymetry by calculating the spatial autocorrelation of model error and integrating this into an improved regression model. Finally, the spatial error model improved the bathymetric estimates of R2 up to 0.854 for log-linear and 0.704 non-linear model respectively. The Root Mean Square Error (RMSE) was calculated for the different depth ranges and also for all reference points. The overall accuracy for the log linear and the non-linear inversion model after the geographical error analysis is estimated as ±1.532 m and ±2.089 m for this study. The spatial error model improved bathymetric estimates than those derived from a conventional log-linear and non-linear technique although these methods perform very similar estimates overall.

Automated Estimation of Coastal Bathymetry from High Resolution Multi-Spectral Satellite Images

Coastal bathymetry is the most essential tool for marine planning, monitoring and management, modelling, nautical navigation and scientific studies of marine environments. The techniques have been developed over the last decade to derive bathymetry using remote sensing technology with efficiently and low costly. Log linear bathymetric inversion model and non-linear bathymetric inversion model provides two empirical approaches for deriving bathymetry from multispectral satellite imagery, which have been refined and widely applied. This paper compares these two approaches by means of a geographical error analysis for the site Kankesanturai using WorldView-2 satellite imagery. In order to calibrate both models; Single Beam Echo Sounding (SBES) data in this study area were used as reference points. Corrections for atmospheric and sun-glint effects are applied prior to the water depth algorithm. The algorithm was tuned and both models were calibrated by performing the necessary algorithm with available single beam echo sounding data in the study area. The coefficients of standard R2 is estimated as 0.846 for log-linear and 0.692 for non-linear model. Log linear model performs better than the non-linear model. The model residuals were mapped and the spatial auto-correlation was calculated based on the bathymetric estimation model. A spatial error model was constructed to generate more reliable estimates of bathymetry by calculating the spatial autocorrelation of model error and integrating this into an improved regression model. Finally, the spatial error model improved the bathymetric estimates of R2 up to 0.854 for log-linear and 0.704 non-linear model respectively. The Root Mean Square Error (RMSE) was calculated for the different depth ranges and also for all reference points. The overall accuracy for the log linear and the non-linear inversion model after the geographical error analysis is estimated as ±1.532 m and ±2.089 m for this study. The spatial error model improved bathymetric estimates than those derived from a conventional log-linear and non-linear technique although these methods perform very similar estimates overall.

Riverscape mapping and hyperscale analysis of the sediment links concept

Longitudinal patterns in channel complexity play an important role in our understanding of fluvial systems. The spatial scales over which external controls such as tributaries, landslides and debris flows, alter channel form and influence the broader basin-wide trends in channel form. Channel complexity across a basin has important implications for how we conceptualize basin-wide trends in channel form such as downstream hydraulic geometry and the sediment links concept. This study takes a hyperscale approach to mapping channel morphology across 200km of the Rogue River in Southwest Oregon - that is high-resolution data over large spatial extents allowing analysis to be conducted simultaneously at and across multiple spatial scales. Using a sUAS and digital photosieving we measured gravels on exposed gravel bars for the study area. We also measured thalweg depth in the field using a singlebeam echo sounder. Slope and channel width were derived using existing GIS datasets. We used these data to create a hyperscale view of the Rogue River examining the impact of tributary and non-tributary sediment links. We used a statistical approach to determine if changes in channel form were truly unique in the context of larger-scale channel variability. Our findings show inconsistent statistical significance of the identified lateral sediment sources (LSS) between variables - e.g. a statistically significant change in slope would not necessarily correlate with an increase in unit stream power. There were many LSS which triggered statistically significant changes to channel form. We used hyperscale graphs to reveal the complexity and spatial trends associated with the relationships between a given sediment link and channel form. The results of this study illustrate the complexity with which sediment links impact channel form and the distances below a given sediment link that a detectable signal exists, if a detectable signal exists.

Testing Different Interpolation Methods Based on Single Beam Echosounder River Surveying. Case Study: Siret River

Bathymetric measurements play an important role in assessing the sedimentation rate, deposition of pollutants, erosion rate, or monitoring of morphological changes in a river, lake, or accumulation basin. In order to create a coherent and continuous digital elevation model (DEM) of a river bed, various data interpolation methods are used, especially when single-beam bathymetric measurements do not cover the entire area and when there are areas which are not measured. Interpolation methods are based on numerical models applied to natural landscapes (e.g., meandering river) by taking into account various morphometric and morphologies and a wide range of scales. Obviously, each interpolation method, used in standard or customised form, yields different results. This study aims at testing four interpolation methods in order to determine the most appropriate method which will give an accurate description of the riverbed, based on single-beam bathymetric measurements. The four interpolation methods selected in the present research are: inverse distance weighting (IDW), radial basis function (RBF) with completely regularized spline (CRS) which uses deterministic interpolation, simple kriging (KRG) which is a geo-statistical method, and Topo to Raster (TopoR), a particular method specifically designed for creating continuous surfaces from various elevation points, contour, or polygon data, suitable for creating surfaces for hydrologic analysis. Digital elevation models (DEM’s) were statistically analyzed and precision and errors were evaluated. The single-beam bathymetric measurements were made on the Siret River, between 0 and 35 km. To check and validate the methods, the experiment was repeated for five randomly selected cross-sections in a 1500 m section of the river. The results were then compared with the data extracted from each elevation model generated with each of the four interpolation methods. Our results show that: 1) TopoR is the most accurate technique, and 2) the two deterministic methods give large errors in bank areas, for the entire river channel and for the particular cross-sections.