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1

Comparing measurement correction of echo sounder in shallow-water area

Zheng Zhaoyong, Jiang Siyi, Zeng Weizhu

Acta Geophysica

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2022

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Vol. 70, no 4

1677--1686

EN

Error correction of echo sounder is very important for the accurate measurement of water-depth in shallow-water area. There are some issues in measuring the water depth, they are accuracy, resolution, inaccurate beamwidth of transmit and can be solved by the existing methodologies. In this article, comparing measurement is an efficient method for error correction of echo sounder. The most commonly used comparing methods are sounding poles, plumb-lines and thermohaline methods. However, the sounding poles method can only measure the water-depth less than 5 m as its limited by the length of measuring poles; the plumb-lines method cannot guarantee the accuracy of water-depth value as its difficult to determine whether the plumb-line falls vertically onto the water floor or into the underwater sediment; the thermohaline methods is time-consuming as its need lots of the temperature and salinity information for the correction of sound velocity. Based on these knowledge and experience, we put forward a comparator for comparing measurement of water-depth, which could adjust sound velocity of echo sounder for precisely measure actual water-depth of the survey area without complicated thermohaline correction work. The comparator method has practical implications for the quick error correction of echo sounder survey in shallow water area. The experimental results predict that the mistakes are easily caused by the complicated correction work which can be avoided and establishes that the water-depth measurement is more efficient.

2

General-purpose unmanned research vessel used for measurement of water depths in reservoirs and their deposits layout

Wolak A., Przecherski P.

Czasopismo Techniczne. Budownictwo

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2014

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R. 111, z. 5-B

291--296

EN

Large artificial water reservoirs are one of the most valuable assets in flood protection. However, the overall volume of a reservoir can decrease over time. This happens mainly because of sediment accumulation, and that alluvia is "eating-up" an otherwise useful volume of water. It is therefore important to know the current volume of sediments accumulated in the reservoir. This way one is able to calculate the useful volume of the reservoir storage capacity, secondly, for assessment of future reservoir operation. The process of obtaining relevant data for this is normally partially automated but nevertheless, it is arduous, extremely time-consuming, and may be dangerous. To overcome those problems we have developed an unmanned vessel, which is able to perform the work much faster and easier. The vessel is a fully unmanned, integrated, nonetheless it is still under development (working prototype 1E), but it can be still easily used in its current state, albeit with some minor limitations.

PL

Duże sztuczne zbiorniki wodne są jednym z najważniejszych ogniw w systemie ochrony przeciwpowodziowej. Całkowita objętość zbiornika nie jest wartością stałą i zmniejsza się w miarę jego eksploatacji. Jako główny czynnik można tu wyróżnić gromadzenie się osadów nanoszonych przez rzekę. Proces pozyskiwania danych do oceny zalądowania zbiornika jest częściowo zautomatyzowany, mimo wszystko jest to zadanie trudne i czasochłonne. Opracowane przez autorów pływające urządzenie pomiarowe sprawia, że pomiary wykonuje się o wiele łatwiej i szybciej. Jest to urządzenie bezzałogowe, zdalnie sterowane i w pełni zautomatyzowane. Prototyp będący w fazie udoskonalania może być z niewielkimi ograniczeniami wykorzystywany do wykonywania pomiarów na zbiornikach wodnych.

3

Effect of in situ radiated noise of the platform used on shallow water area on echo sounder data in fisheries-acoustics

Brehmer P., Guennegan Y., Arzelies P., Guillard J., Cheret Y., Duformentelle P., Colon M.

Hydroacoustics

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2003

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Vol. 6

31--40

EN

The shallow water area of the coastal fringes is important to take into consideration in fish stock assessment because a great part of the stock, especially for the small pelagic fish is distributed in this area (20). In shallow water research vessels are prohibited to navigation (usually <20m) and usually only small boats can be used. One of the main source error in acoustics fish sampling is due to the avoidance reaction generated by the three dimensional noise diagram emitted by the boat. In this paper we highlighted the importance of wind direction and strength in the noise diagram emitted by the boat under in situ condition. A comparison of the noise level of two boats (a Research Vessel and a Speedboat equipped of similar echo sounder) has been made before simultaneous records of echo sounder data: the speedboat is more silent as revealed by in situ hydrophone measurement and near the ICES recommendations. The observation of shoal echo sounder descriptors shows an avoidance reaction as expected more important for the noisier boat: there the schools avoid more the research vessel. The avoidance reaction is characterised by a deeper position of the fish school barycentre, in the water column, detected by the research vessel and a shoal minimum depth higher than for the speedboat. The effect of noise diagram difference is clear on the same shoal descriptors, the difference appears for the vertical position of the barycentre and minimum altitude.

4

Acoustic experiment on diel fish behaviour cycle performed in the Gotland Deep

Orlowski A.

Hydroacoustics

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2003

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Vol. 6

19--30

EN

This paper describes the results of 24 h acoustic experiment based on three-dimensional measurements of the S; distribution of herring and sprat in the southern Baltic in October 2001. The experiment was based on a continuous (24h day) integration offish echoes using an EY500 echo sounder from a vessel with a constant speed of 8 knots, moving along the sides of a square equal to 4 n.mi., localized inside the specified area. Duration of the experiment was limited by deterioration of the weather conditions but nearly 300 ESDU samples were collected. These are correlated with values of coincident environmental factors: time, depth, water temperature, salinity and oxygen levels; estimated on the basis of survey data. Fish behaviour vs environmental factors is described by different macrosounding visualizations, statistical, and mathematical models. The purpose of the paper is to compare results of the experiment to the average characteristics of fish behaviour in the same basin, based on autumn studies over the period 1995-2001. General analysis was provided for the selected area of the Polish EEZ (south Gotland Deep), characterized by the greatest depth movements of fish diel migration. The most significant differences were found between fish migration pattern and diel stability of the acoustic response between these situations, specially during the sunset period.

5

Ocena dokładności pomiaru głębokości na rzece za pomocą echosondy samopiszącej

Pacześniak E., Kosicki M.

Gospodarka Wodna

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2003

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Nr 3

124-130

EN

The paper presents results of tests measurements of water depth using the echo sounder ESDA-14. There has been also made an analysis of the impact of velocity and direction the vessel is following on the accuracy of measurements.