Parametric Sub-bottom Profiler Research Articles

Implementation of comparative detection approaches for the accurate assessment of sediment thickness and sediment volume in the Passaúna Reservoir

Siltation has significant economic and social impacts as it directly reduces the useable amount of water in reservoirs. Giving a solution to the issue of sedimentation is a complicated task and maybe one of the most important engineering and environmental challenges of the 21st century. The deposited volume and the distribution pattern of the sediment are often unknown and not easy to assess. The sedimentation process is highly dynamic, initially due to the hydrological conditions of the incoming rivers, but also due to common internal phenomena like resuspension or density currents. Sediment remediation measures such as mechanical sediment removal or flushing are planned based on the sediment thickness distribution and the overall sediment volume/mass. Often, the sediment thickness is calculated through topographic differencing between the pre-impoundment reservoir lake bottom and the actual lake bottom. However, it is common that the previous depth distribution map is not available or in insufficient quality. In this regard, alternative measurement techniques have to be taken into consideration. In this study, we assessed the best possible approach depending on the characteristics of the sediment and of the reservoir. We combined three different acoustic systems (a multibeam, a sub-bottom profiler, and a single beam dual frequency system) with sediment coring and dynamic free fall penetrometer measurements for an improved assessment of sediment stock and sediment distribution in the Passaúna Reservoir. Our results showed that topographic differencing could not be applied, as the data for the pre-impoundment lake bottom was insufficiently accurate. The parametric sub-bottom profiler could detect the sediment thickness in high accuracy, but significant limitations were recorded in areas with high gas contents. The dual-frequency echosounder derived the sediment thickness with a normalized mean absolute error of 56% due to the high volumetric gas content in the sediment. The dynamic free-fall penetrometer showed satisfying results compared to the other systems. The normalized mean absolute error was 22%, and sediment thickness could be detected in areas with up to 1.8 m of sediment. Sediment coring is also a reliable technique for sediment thickness determination. However, the results showed that if only traditional coring devices are used (gravity corer), the limited penetration depth of the equipment combined with sampling disturbances often prevent a correct assessment of the sediment thickness. The overall results of this study can help for an improved decision-making regarding reservoir management. The accurate assessment of sediment volume and distribution can reduce costs for sediment removal and assist in having a precise overview of the reservoir lifetime.

Impact of Late Cretaceous to Neogene plate tectonics and Quaternary ice loads on supra-salt deposits at Eastern Glückstadt Graben, North German Basin

In this study, we investigate the impact of Late Cretaceous to Neogene plate tectonics and Pleistocene ice load on the post-Jurassic strata above the Waabs salt wall within the Eastern Gluckstadt Graben by integrating reflection seismic, parametric sub-bottom profiler and well data. Previous studies showed that a collapse graben developed above the salt during several tectonic pulses. However, due to the lack of age constrains, the relationship between local salt tectonics and variations of the regional stress field caused by plate tectonics was just little constrained. Here, we introduce an inter-Cenozoic stratigraphy enabling us to infer and date three major salt tectonic phases. During the Late Cretaceous to Eocene, Africa–Iberia–Europe convergence and subsequent Pyrenean orogeny strata above the salt wall were pushed upwards and faulted. Thickness variations of the Upper Cretaceous and Eocene strata imply at least two pulses for this upward push. The second phase includes the major graben collapse in the Neogene, when the stress regime changed from a compressional to an extensional regime. The third phase is a period of locally differing tectonic reactivation likely caused by ice sheet loading and unloading during the Quaternary. Based on time-isochore and time-structure maps, we elucidate how this last glacial phase of salt tectonic movement likely formed the present day Mittelgrund shoal within the Eckernforde Bay. The spatial correlation between shallow faults and freshwater seepage implies further a causal relationship between fluid migration and faulting.

Relief and internal structure of the subaqueous sand dunes in the Vistula River mouth

This paper presents the results of bathymetric and seismoacoustic measurements carried out in the canal of the Vistula River mouth (pol. Przekop Wisły). The surveys were conducted with the use of a multibeam echosounder and a parametric sub-bottom profiler. It made it possible to obtain a high resolution bottom morphology measurement, and to identify and characterize an internal structure of subaqueous bedforms. Presence of multiple series of small to large dunes, with their length ranging from 5 up to 55 m and height from 0.1 up to 1.5 m, was established. They were composed mainly of poorly graded medium-grained sands. The nature of the sediment graining was relatively uniform. Significant diversity in terms of the formation sizes was observed, and itwas only loosely dependent on their depth and location within individual relief units. Collateral medium and small formations were found everywhere among the large formations. The bedforms consisted of well-developed steep cross-coset stratification structure. It has been ascertained that the cross-coset thickness of this formation was greater (or equal) than its height. The scope of this work is to identify the relief and structure of subaqueous dunes for the purpose of the assessment of flow properties and bottom conditions in both recent and palaeoenvironments. The obtained results are crucial for determining the state of the Przekop Wisły canal, indicating potential limitations to unconstrained flow of spate water and ice drifting as well as navigation conditions.

Parametric sources—From theory to commercial products

The interest for underwater application of nonlinear acoustic began in the late 1950s and early 1960s with Westervelts idea of using nonlinear effects to generate low frequency sound beams with high directivity; the parametric source. This idea got a lot of attention during the 1960s and 1970s from various scientific institutions. An early experiment with a parametric source was performed by ELAB at the University of Trondheim and Simrad in 1977. In the early 1980s, Bentech started the design of a towed, combined mapping system for bathymetry and detection of buried pipelines. The idea was to do detection while moving along the pipeline, which required a sub-bottom profiler with steerable beams with high directivity. Due to limited space for transducer, a parametric source was the logical choice. A prototype of the parametric sub-bottom profiler was finished in the late 1980s. Following the prototype, the system was commercialized and additional versions were developed covering applications from shallow water, high resolution work to full ocean depth, high penetration work. Today KONGSBERG is a world leading supplier of parametric sub-bottom profilers.

Development of the Parametric Sub-Bottom Profiler for Autonomous Underwater Vehicles and the Application of Continuous Wavelet Transform for Sediment Layer Detections

Development of the Parametric Sub-Bottom Profiler for Autonomous Underwater Vehicles and the Application of Continuous Wavelet Transform for Sediment Layer Detections

Assemblages of submarine landforms in the glacial troughs of the northern Barents Sea, east of Svalbard

The Barents Sea is a wide, relatively deep epicontinental sea consisting of shallower banks ( c. 50–100 m depth) separated by broad, flat-bottomed troughs ( c. 200–400 m depth) that radiate out towards its western and northern margins (Fig. 1a). These troughs have been excavated by grounded ice during multiple glaciations through the Plio-Pleistocene (Jakobsson et al. 2014). During the Last Glacial Maximum (LGM) the Barents Sea Ice Sheet (BSIS) extended across the entire northern Barents Sea to the shelf break (Svendsen et al. 2004; Jakobsson et al. 2014). Fast-flowing ice drained the ice sheet through these troughs and produced a suite of seafloor landforms that preserves both a record of former ice-flow patterns and of how the ice sheet retreated during deglaciation (Dowdeswell et al. 2010; Hogan et al. 2010 a ). Fig. 1. Bathymetric images and sub-bottom profiles of landforms in glacial troughs east of Svalbard. Acquisition system Kongsberg EM120. Frequency 12 kHz. Grid-cell size 10–20 m. Acquisition system for profiles Kongsberg TOPAS PS018 parametric sub-bottom profiler (secondary beam frequency 0.5–6 kHz). ( a ) Location of study area (red boxes; map from IBCAO v. 3.0). KT, Kvitoya Trough; OT, Olga Trough; E, eastern Erik Eriksen Trough; W, western Erik Eriksen Trough; KKL, Kong Karls Land; No, Nordaustlandet; FVT, Franz Victoria Trough. ( b ) Glacial lineations (long dashes) overprinted in part by a debris-flow deposit (dotted) in western Erik Eriksen Trough; recessional moraine orientations shown by solid lines. Large black arrow indicates former ice-flow direction. ( c ) Saw-tooth-shaped recessional moraines in Olga Trough. ( d ) Hill–hole pairs and glacial lineations in eastern Olga Trough; same depth scale as (c). ( e ) Streamlined crag-and-tail landforms in Kvitoya Trough. ( f ) Sub-bottom profile over the till sheet and recessional moraines shown in (c). ( g ) Acoustic facies on the upper slope north of Kvitoya Trough. ( h ) Subglacial meltwater channels …

Seismic acoustic research in the area of Golubaya Bay of the Black Sea conducted by the R/V Ashamba

One of the main goals of the expedition was the acceptance trial and development of operational techniques for the SES 2000 Light Plus parametric subbottom profiler newly acquired within the frame of the State Contract (produced by Innomar Technolo gie GmbH, Germany) consisting of a new generation acoustic bottom profiler and a sidescan sonar pro duced by the same company and structurally compat ible and combined with the profiler. In addition, the obtained data were compared with the results of the hardware–software complex Teont Shelf, which is a complete system for research by single channel con tinuous seismic profiling (CSP) using a sparker type emitter and a pick up loop 20 m long. The simulta neous operation of the above mentioned systems in close proximity to each other made it possible to clar ify the degree of their mutual influence and enhance the interpretation of the data.

A geoacoustic estimation scheme based on bottom backscatter signals from multiple angles

Aiming at the disadvantages of current methods to estimate sediment geoacoustic parameters, a geoacoustic estimation scheme is presented, in which used are the bottom back reflection signals from multiple angles sampled with a multi-beam parametric array sub-bottom profiler. Firstly, the sediment thickness and sound speed are estimated with difference frequency backscatter signals separately from upper and lower sediment surfaces with vertical and outboard direction. Then, the sediment attenuation coefficient is estimated by use of the two backscatter signals with different difference frequencies from upper and lower sediment surfaces with vertical direction. Finally, the sediment property impedance is estimated with primary frequency backscatter signals from upper sediment surface with vertical direction and followed by the computation of the sediment density, thereby solving its coupling with sound speed. The efficiency is tested through pool experiment.

Gdansk Bay sea bed sounding and classification of its results

AbstractThe main goal of this paper is to describe the results of sounding the Gdansk Bay sea bed by using a SES- 2000 Standard parametric sub-bottom profiler. Quality of data obtained during trials depends inter alia on a proper location of transducer array to reduce influence of pitch, roll and heave motions as well as ship self noise (resulting from bubbles due to propeller and flow around hull, vibration generated by main engine and auxiliary devices). Furthermore, calibration of complementary units such as GPS, heading sensor, MRU-Z motion sensor and navigation devices make sea-bed investigating system capable of working with its whole capability. Results of so prepared surveys have been presented and discussed. They contain also an elaborated map of Gdansk Bay with preliminarily classified sea-bed materials and description of most interesting areas.

The West Melilla cold water coral mounds, Eastern Alboran Sea: Morphological characterization and environmental context

A new mound field, the West Melilla mounds, interpreted as being cold-water coral mounds, has been recently unveiled along the upper slope of the Mediterranean Moroccan continental margin, a few kilometers west of the Cape Tres Forcas. This study is based on the integration of high-resolution geophysical data (swath bathymetry, parametric sub-bottom profiler), CTD casts, Acoustic Doppler Current Profiler (ADCP), ROV video and seafloor sampling, acquired during the TOPOMED GASSIS (2011) and MELCOR (2012) cruises. Up to 103 mounds organized in two main clusters have been recognized in a depth range of 299–590m, displaying a high density of 5mounds/km2. Mounds, 1–48m high above the surrounding seafloor and on average 260m wide, are actually buried by a 1–12m thick fine-grained sediment blanket. Seismic data suggest that the West Melilla mounds grew throughout the Early Pleistocene–Holocene, settling on erosive unconformities and mass movement deposits. During the last glacial–interglacial transition, the West Melilla mounds may have suffered a drastic change of the local sedimentary regime during the late Holocene and, unable to stand increasing depositional rates, were progressively buried. At the present day, temperature and salinity values on the West Melilla mounds suggest a plausible oceanographic setting, suitable for live CWCs. Nonetheless, more data is required to groundtruth the West Melilla mounds and better constrain the interplay of sedimentary and oceanographic factors during the evolution of the West Melilla mounds.

Utilizing a seismoacoustic complex for the study of the upper sedimentary stratum and seafloor relief in East Arctic

The paper describes a high-resolution seismoacoustic complex for studying the upper sedimentary stratum and seafloor relief. The described complex was used during the 57th cruise of the R/V Akademik M.A. Lavrent’ev in the East Siberian and Laptev seas in the autumn of 2011. The combination of an SES-2000 narrow-beam parametric subbottom profiler and a Gidra 250/500 sidescan sonar has enabled obtaining a series of unique data on the structure of the sedimentary layers and the seafloor relief.

Processing data on sea bottom structure obtained by means of the parametric sounding

ABSTRACT The aim of the paper is to analyze data obtained during sounding the Gdansk Bay sea bed by means of the parametric echo-sounder. The accuracy of the sea bottom structure investigation needs correct configuration of research equipment and proper calibration of peripheral devices (GPS, heading sensor, MRU-Z motion sensor and navigation instruments which provide necessary data to bathymetrical measurement system, enabling its work with full capability. The parametric sub-bottom profiler delivers two types of data which include different information: envelope and pure echo signal sampled without processing. The first is used to present echograms in real time and the second one is stored during sounding and the obtained data can be analyzed by using post-processing software. Differences in the results are presented and discussed. And, are described also criteria taken into account during determination of the measurement areas and selection of different configurations of the software according to the information to be obtained from trials. Complementary information can be achieved from processing the data by means of the procedures offered by Matlab software, which allows for a clear 3D presentation of the results. The consideration are illustrated by echograms taken in the natural conditions

Monitoring the volume and lateral spread of disposed sediments by acoustic methods, Oslo Harbor, Norway

Acoustic equipment, including interferometric sonar and parametric sub-bottom profiler, have been used to determine the volume and lateral spread of dredged sediments disposed in the natural submarine depression in the Bekkelag Basin, inner Oslofjord since the beginning of the Oslo Harbor remediation project in 2006. This natural depression is used as a subaqueous confined disposal facility (CDF). Calculation of the volume of disposed sediments in the CDF is based on elevation change, derived from two high-resolution bathymetric datasets obtained in 2004, i.e. before the onset of the remediation project, and in April 2008. Seismic profiles across the CDF have been used to estimate the settlement of the original seabed, caused by loading-induced dewatering and compaction of the seabed sediments under the disposed masses. Detailed bathymetry and backscatter data demonstrate the lateral spread of disposed sediments within a well-confined area covering ca. 195,000 m 2. The sea bottom within this area is distinctly softer than the surrounding seabed as shown by very low acoustic backscatter amplitude, signifying a very loose surface character of the disposed sediments. The thickness of the disposed sediments reaches 6 m the deepest part of the original depression. The volume calculation of the disposed sediments in the CDF, based solely on bathymetry data, gives a value of ca. 310,000–320,000 m 3. Settlement of the original seabed as a result of loading has been estimated to be 30 cm at 5 m thickness of the disposed sediments. Under the condition that the settlement rate is linearly correlated to the thickness of disposed sediments, the settlement corrected volume of disposed sediments is ca. 330,000–340,000 m 3. Presented results demonstrate high accuracy and good reproducibility of acoustic seafloor data, and indicate a great potential of such methods as monitoring tools in environmental projects that involve dredging and subaqueous disposal.

Active Venting System Offshore Northern Norway

A combined sediment‐sampling, high‐resolution seismic, multiple echo sounder, and video survey was conducted offshore Vestårlen, northern Norway, in October 2007 as part of the ongoing Marine Area Database for Norwegian Coast and Oceanic Regions (MAREANO) program. MAREANO is a multidisciplinary seabed mapping program conducting physical, biological, and environmental mapping in the Lofoten/southern Barents Sea area. Data and analysis arising from this program will provide the basis for ecosystem‐ based management of Norway' coastal and offshore regions. The survey used multicorer, box corer, and grab samplers; a TOPAS parametric subbottom profiler; 18‐, 38‐, 70‐, 120‐, 200‐, and 400‐ kilohertz echo sounders; and a CAMPOD camera system with two video cameras and lights mounted on an aluminum frame.

Calibration sphere for low-frequency parametric sonars

The problem of calibrating parametric sonar systems at low difference frequencies used in backscattering applications is addressed. A particular parametric sonar is considered: the Simrad TOPAS PS18 Parametric Sub-bottom Profiler. This generates difference-frequency signals in the band 0.5-6 kHz. A standard target is specified according to optimization conditions based on maximizing the target strength consistent with the target strength being independent of orientation and the target being physically manageable. The second condition is expressed as the target having an immersion weight less than 200 N. The result is a 280-mm-diam sphere of aluminum. Its target strength varies from -43.4 dB at 0.5 kHz to -20.2 dB at 6 kHz. Maximum excursions in target strength over the frequency band due to uncertainty in material properties of the sphere are of order +/-0.1 dB. Maximum excursions in target strength due to variations in mass density and sound speed of the immersion medium are larger, but can be eliminated by attention to the hydrographic conditions. The results are also applicable to the standard-target calibration of conventional sonars operating at low-kilohertz frequencies.

Fluid mud dynamics in the Weser estuary turbidity zone tracked by high-resolution side-scan sonar and parametric sub-bottom profiler

Fluid mud in estuarine turbidity maximum zones (TMZ) can pose considerable navigation risks due to potentially substantial reductions in nautical depth, coupled with an inherent difficulty of detection by conventional echo-sounders. Despite intensive research efforts, however, our knowledge about the spatial and temporal dynamics of fluid mud is still not sufficient. In this study, the combined use of a side-scan sonar (Sportscan®, Imagenex) and a parametric sub-bottom profiler (SES-2000®, Innomar Technology GmbH) has proved successful for high-resolution fluid mud detection and volumetric quantification in an estuarine environment. In 2004 and 2005, repeated surveys were conducted in the navigation channel of the upper meso- to lower macrotidal Weser estuary TMZ (German North Sea coast) at different tidal stages and river discharges. Current velocity data were simultaneously collected by 1,200-kHz broadband ADCP (RDInstruments) measurements. Ground-truthing was carried out by means of grab sampling and gravity coring, adapted to fluid mud conditions. It was found that fluid mud occurrence in the Weser estuary is highly variable on time scales of a few hours and spatial scales of several metres. The riverbed is characterised by sand and mud deposits, and a complex morphology including subaqueous dunes and smooth bed deposits intermittently overlain by fluid mud. Thus, a continuous, coherent fluid mud body covering the entire TMZ riverbed was not observed. Rather, spatial distribution was patchy and highly dependent on suspended particulate matter (SPM) concentrations in the water column, as a result of which local fluid mud deposits varied in thickness from centimetres to metres. The formation of fluid mud was largely restricted to slack water, although slack-water conditions were not necessarily associated with large-scale fluid mud appearance. Advective SPM transport of resuspended fluid mud seems to be the most plausible explanation for the high spatial variability observed, even between two successive tides. The amount of fluid mud deposited and resuspended in the course of a tidal cycle can reach several 10s of tons even in small riverbed depressions.

Morphology and sedimentary processes on the continental slope off Pine Island Bay, Amundsen Sea, West Antarctica

Morphology and sedimentation on the Pine Island Bay continental margin, eastern Amundsen Sea, is investigated using swath bathymetry, parametric subbottom profiler (TOPAS) records, and sediment cores. A major cross-shelf trough extends to the continental shelf edge at 114°W, through which fast-flowing ice drained the West Antarctic Ice Sheet under full-glacial conditions. The slope adjacent to the trough mouth is 4°, whereas to the east and west it is steeper. A bulge in bathymetric contours beyond and east of the trough mouth indicates some slope progradation. Elsewhere, seismic-reflection profiles indicate major shelf aggradation and minor slope progradation. Networks of gullies and channels dominate the slope adjacent to Pine Island Bay. In front of the trough mouth, gullies at the shelf edge and uppermost slope connect directly with channels that continue to the continental rise. Other gullies connect indirectly with channels further downslope. TOPAS records indicate that gully-channel systems acted as conduits for coarse-grained sediment transfer. Cores comprise turbidites representing channel deposits and diamicton facies deposited by debris flows. Sandy turbidites interbedded with hemipelagic muds occur on the rise and abyssal plain. The West Antarctic Ice Sheet extended to the shelf edge during full glacials, delivering water-saturated till and turbid water directly to the continental slope along a line source. Gully-channel systems are probably a product of sediment gravity flows derived from the release of water-saturated till and turbid water along the ice-sheet margin, perhaps augmented subsequently by downslope flow of dense cold and saline water associated with sea-ice production during the Holocene. The gully-channel systems enable sediment to bypass the continental slope. Spatial variations in gully-channel system morphology along the Amundsen Sea continental slope are probably linked to differences in sediment gravity flow processes and the rate and composition of sediment delivered to the shelf edge from the ice sheet. Cored sediments on the slope and abyssal plain record the widespread presence of turbidite sands, indicating that downslope transfer of glacier-derived sediments has taken place. This supports our interpretation that submarine channels are derived from, and are conduits for, mass wasting. Submarine channels on the upper slope continue into the abyssal plain as far north as ∼67°S. They are separated by sediment drifts and sediment waves resulting from the interaction between downslope turbidity current processes and along-slope bottom currents. Similar deep-sea sedimentary processes operate along much of West Antarctica and the western side of the Antarctic Peninsula.

Continental slope morphology and sedimentary processes at the mouth of an Antarctic palaeo-ice stream

Continental-slope and shelf-edge morphology off Marguerite Bay, western Antarctic Peninsula, is investigated using swath-bathymetric data and parametric sub-bottom profiler records, together with sediment cores. Marguerite Bay has a well-defined cross-shelf trough, and a relatively steep continental slope. The slope beyond the trough mouth is convex in longitudinal profile, whereas to the north and south it is concave and reaches a maximum of 12°. There are no deep canyons cutting into the prograding outer shelf and slope. Instead, a series of gullies runs down the upper slope, reaching depths of >200 m south of the trough mouth but <120 m deep beyond the trough. The mid and lower slope appears to be relatively smooth and downslope sediment transfer is probably by small-scale slides, slumps and debris flows. The continental rise contains dendritic channels related to turbidity currents, and sediment drifts produced by southwest-flowing bottom currents from the fine-grained component of the turbidity currents. Elongate sedimentary bedforms indicate that a fast-flowing ice stream occupied the trough under full-glacial conditions, and transferred deforming subglacial till rapidly to the shelf edge. By contrast, on either side of the trough mouth, ice is inferred to have been slower-moving and probably cold-based, delivering little sediment to the upper slope. The steepness of the continental slope results in rapid downslope sediment transfer by debris flows, slumps and turbidity currents and accounts for the lack of a well-developed trough-mouth fan, which is typical of many lower-gradient glacier-influenced margins.

深海無人探査機用パラメトリック・サブボトムプロファイラ

A sub-bottom profiler system for remotely operated vehicle in deep sea was developed to observe surface sedimentary layers of several thousand meter-depth. Using a parametric acoustic array, we realized a very narrow beam width of 4 degrees with the frequency of 3.5 kHz. In this report, first, the dependency of the secondary pressure levels of parametric acoustic sources on the depth of water is calculated by the use of the physical data obtained in real sea. As the result, it is shown that the second pressure levels become slightly higher in deep sea of 6, 000 m than the values at sea surface. Next, a prototype of the parametric source for the experiments under ordinary ambient pressure is developed and tested. The experimental data obtained in water tank agree with the calculated values. Then, in the field experiments of the sub-bottom profiling at the wharf in comparison with the conventional source. Finally, we developed a parametric sub-bottom profiler for 10, 000 m class ROY, and acoustic characteristics of these equipments measured in water tank and experimental results in shallow water are shown.