CC BY
3Гидрология
Гидрология
Hydrology
https://doi.org/10.55764/2957-9856/2022-4-ll-19.19
UDC 556.5
M. O. Fatkhi1, P. N. Tersky2, I. A. Kopeikin3
1 Junior research (FSBI State oceanographic institute named N. N. Zubov, Moscow, Russian Federation) 2 PhD of geographical sciences, senior research associate (FSBI State oceanographic institute named N. N. Zubov, Institute of water problems of the Russian academy of sciences, Moscow, Russian Federation) 3 Engineer (FSBI State oceanographic institute named N. N. Zubov, Moscow, Russian Federation)
MODERN METHODS OF HYDROMETRIC RESEARCH: BATHYMETRIC WORKS USING ECHO SOUNDER
Abstract. The study of the morphometry of the bottom of water bodies is an important task in various areas of economic, industrial, and other activities, as well as scientific research. Therefore, it is necessary to develop and use modern methodological solutions in applied hydrography for carrying out bathymetric works and processing the obtained material.
This article examines modern methods of working with echo sounders, covering theoretical and practical aspects of using these devices. The article presents an overview of existing echo sounder classifications, methods for performing survey work in expeditionary conditions, and compiling final materials in the form of tables and vector layers.
The main aspects of working with echo sounders are considered, such as equipment selection, parameter setting, conducting survey work, processing and analyzing data, and their integration with geographic information systems. Innovative developments and technologies that contribute to improving the quality and accuracy of results are described.
Special attention is paid to the integration of echo sounders with other technologies, such as geographic information systems (GIS). The authors also consider practical aspects of using echo sounders in navigation, hydrography, and other areas.
This article provides a valuable overview for professionals in the field of hydrology and related areas, studying the morphometry of the bottom of water bodies, as well as for a wide range of readers interested in innovative technologies and the field of acoustics and geographic information systems.
Keywords: survey work, geographic information systems (GIS), bathymetry, echo sounder, hydrostatic logger.
Introduction. Depth finders, or sonars, are an indispensable tool in hydrography, marine navigation, and conducting natural scientific research. They allow determining the depth of water bodies and the relief of the seabed, which plays a crucial role in ensuring the safety of navigation, developing infrastructure projects, and studying underwater ecosystems. Due to the variety of applications for sonars, as well as the constant development of technologies and new sonar models, there is a need to develop modern and efficient methodologies for working with these devices. The aim of this article is to present contemporary types of sonars, their operation, equipment preparation and setup, and analysis of the obtained data. The article will discuss the main principles of sonar operation and the specifics of using different types of sonars depending on the tasks and conditions of the measurements. We hope that the proposed methodology will be useful for professionals in hydrography, marine navigation, and oceanography, as well as for underwater enthusiasts who wish to master the operation of sonar for their research or recreational purposes.
General information. Nowadays, the most accurate and simple device for measuring the depths of water bodies is the sonar. The basics of its functioning principle have been extensively described in publications of the 20th century (Korotkin I.M., Nefedov P.M., 1985; Lavrentiev A.V., Bogdanovich M.L., 2007). In recent years, the development and improvement of sonars have significantly advanced thanks to digital technologies.
Most modern research in the field of sonars covers their principles of operation, including acoustic location, signal processing, and visualization (Medwin & Clay, 2021). In particular, sonars are divided into single-frequency and multi-frequency, and each group has its advantages and disadvantages (Simmonds & MacLennan, 2005). The literature also presents a classification of sonars by the type of emitted signals, dividing them into short-pulse and broadband (Meyer & Simmonds, 2021).
Modern sonars are used in various fields, ranging from navigation and hydrography to oceanography and fishing. In particular, sonars are used to create detailed maps of sea and ocean depths, as well as inland water bodies, which significantly simplifies navigation and allows identifying suitable fishing areas. It should be noted that measuring depth without geographic referencing has a number of limitations for further data use. Therefore, methods of geodetic referencing of measurement materials using various geodetic devices and global satellite positioning systems have been developed, as well as regulatory documents regulating the operation of this equipment, for example, in construction (e.g., СП РК 1.02-1012014, OT^ 104.97). These documents introduce, for example, restrictions on the vessel's speed during measurements, methodology for laying survey lines, density of measurement points, and more. In recent years, there has been active development of technologies for collecting, recording, and transmitting sonar data, which significantly increases their efficiency and accuracy. In particular, researchers have focused on the development of signal processing algorithms, adaptive methods of acoustic location, and integration with other technologies.
Modern signal processing algorithms significantly increase the sensitivity of sonars and reduce the impact of noise. The use of methods such as signal compression, filtering, and source localization allows processing large volumes of data and visualizing complex seabed structures. Adaptive methods of acoustic location represent a new approach to determining depth and forming an image of the water body's bottom using variable parameters of the acoustic signal. These methods allow effectively determining depth in complex conditions, such as noise interference or variable geometric conditions.
Modern sonars are increasingly integrated with other technologies, such as geographic information systems (GIS), laser, and multisensor systems. Such integration significantly improves the accuracy and reliability of the data obtained and expands the application field of sonars, for example, in geology, hydrology, and other applied areas. The result of measurements by such sonars is a set of tabular data in various formats, containing information about the coordinates of the measurement area, depths at that area, and some other information obtained during the operation of the device.
The data is converted into a point vector file for subsequent integration into the GIS structure. There are many GIS packages that allow visualizing and processing measurement results, such as ArcGIS, QGIS, GlobalMapper, Surfer, and others. The format of the final hydrographic survey data depends on the specific research objectives. In the case of creating cartographic materials (e.g., navigation charts), the result is isobaths and depth marks. Such a vector dataset can be generated manually or automatically, without requiring attachment to a height system (e.g., Baltic Height System), while the frequency of contour lines is determined by the scale of the cartographic material and the depths of the water body.
If the primary goal is to integrate hydrographic data into a universal cartographic base (e.g., topographic or terrain relief maps), it is necessary to link the data to a local or global height system using topographic-geodetic methods. In specific cases, when research is aimed at calculations or modeling of various processes and phenomena, the final product becomes digital terrain models. This material represents an area continuously covered with information with a certain spatial resolution and a given height accuracy.
Types of sonars. Currently, there is an extensive assortment of sonars, which, in the authors' opinion, can be classified into several main categories without considering specific models and manufacturers.
The first category includes portable sonars (figure 1), which are devices that determine depth by immersing the sensor in water and activating the measurement function. Such devices do not provide continuous acoustic imaging, measurement positioning, or erroneous data correction (e.g., double signal reflections).
a b c
Figure 1 - Portable sonar (a), Stationary sonar (b), Multibeam sonar (c)
The second category is represented by stationary sonars installed on vessels. These devices consist of an echolocation sensor, chart plotter, and power supply unit. They are equipped with built-in global positioning systems, such as GPS and GLONASS. These sonars allow for continuous data recording. The chart plotter screen can track any changes in depths and the vessel's position in real-time, as well as detect object profiles on the seabed or water column using a continuous echogram. A disadvantage of these devices is the integration of the satellite positioning module into the chart plotter, which can be located far from the sonar sensor. This leads to a decrease in positioning accuracy and orientation, and as a result, a deterioration in depth measurement quality.
The third category also includes stationary, high-precision sonars equipped with sensors connected to personal computers (e.g., rugged and water-resistant laptops) and appropriate software (e.g., Hypack). This type of instrumentation complex provides minimization of vertical error and allows for programma-tically defining the shape of pre-prepared materials, eliminating several stages of data processing. Positioning occurs using an external antenna, also connected to a personal computer.
The fourth category comprises multibeam sonars, hydrolocators, and structural scanners. These devices provide area scanning on both sides of the sensor axis, creating a detailed bottom image. Such images can be used to assess the type of bottom sediments, planar shape of bottom relief, position, and genesis of sunken objects, etc. This information is useful for studying bottom structure but is excessive for creating cartographic materials. Disadvantages of this type of equipment include high operational complexity, significant mass of the instrument complex, and high cost.
There are also other types of sonars that are currently gaining popularity. For example, a spherical sonar with Bluetooth, installed on a fishing rod or unmanned aerial vehicles, and operating through a mobile phone application; radio-controlled sonar on a boat, etc.
However, these types of devices will not be considered in this article. To ensure the highest spatial accuracy of measurements, high-precision geodetic satellite positioning equipment is used (e.g., GNSS receiver), which significantly reduces the spatial measurement error.
During experiments with various types of sonars, it was found that for conducting surveying work on relatively small water bodies (small and medium rivers, short sections of large rivers, small lakes and reservoirs, coastal areas of seas), the second and third categories of sonars are the most optimal. These sonars are relatively inexpensive, easy to operate, and mobile, do not have a large mass, which allows them to be installed on a small vessel.
The use of sonars in scientific research. Currently, stationary Lowrance and Garmin sonars have become widely popular in the academic environment when working on relatively small water bodies. These systems are characterized by relatively easy installation, high measurement accuracy (depending on the model), the possibility of modification, and application on small vessels. The choice of a suitable floating device imposes limitations on the equipment used.
The optimal solution is an inflatable boat with a rigid transom or a boat with a shallow draft. The sonar sensor is installed using a retractable clamp attached to the transom, submerging the sensor at a depth where the influence of the motor propeller is minimal (usually about 0.3 m). When analyzing the measurement results, this value should be taken into account and added to all the obtained data. The chartplotter is placed as close as possible to the sensor installation site, providing the captain's convenience in familiarizing themselves with the information on the screen.
The power supply unit (usually operating from 12V car or motorcycle batteries) is installed in a hermetic container. When conducting continuous measurements, a track plan is developed in advance and imported into the sonar (figure 2). Visualizing the work plan on the display significantly simplifies the process and ensures more regular coverage of the area with a survey grid. For Lowrance sonars, the preliminary development of a work plan in the form of measurement tracks is performed in the .usr format. Data preparation can be carried out using various GIS packages (for example, Global Mapper).
Figure 2 - Preparation of the track plan in the GIS package Global Mapper (a), screen of the Lowrance HDS-5 chartplotter during work with the displayed track (b)
According to (Cn PK 1.02-101-2014, CHnn 104.97), the measurement speed may vary depending on the tasks and equipment used. The technical specifications of Lowrance sonars and their analogs provide the manufacturer's stated accuracy of depth and positioning measurements when the boat is moving at a speed of no more than 18 km/h. In continuous recording mode, measurements can be made with high regularity, which allows for the identification and elimination of incorrect data, both in automatic and manual modes.
Thanks to the presence of at least two depth and coordinate records at each measurement point, as well as the limited distance between adjacent points (no more than tens of centimeters), calculating the outlier value becomes relatively simple. The type of water body, meteorological, and other conditions impose a number of requirements and limitations on the process of performing hydrographic work. In addition to river flood levels, the water level in the lower reach of reservoirs can change significantly due to the regulation of discharges from the hydro-node, and on counter-regulatory reservoirs and ponds of HPPs, work may be accompanied by regular changes in water levels.
To account for changes in water levels in the results of survey work, it is necessary to link the water level at the beginning, end, and often during the fieldwork period. This can be done by organizing temporary water meter posts or using information from network water meter posts. A modern solution to this issue involves using hydrostatic or optical water level recorders (loggers). The optical recorder is installed above the water body and regularly measures the water level using a built-in optical rangefinder.
The hydrostatic recorder is placed in the water column and records the total pressure exerted on the sensor (figure 3 - hydrostatic and atmospheric pressure). The correction of measurements for atmospheric pressure is based on data from the nearest meteorological stations or using an additional recorder installed on land.
Thus, modern approaches to conducting sonar measurements, including the use of continuous recording and accounting for changes in water level, allow for increased accuracy and reliability of the
Figure 3- Solinst Levelogger hydrostatic water level recorder (a) and a graph of water levels and temperature changes based on recorder measurements (b)
obtained data, which is a key factor when performing survey work under various conditions and on different water bodies.
Processing measurement materials. Sonars from various manufacturers generate files with different formats and resolutions during operation. The software designed to work with such files may also vary depending on the device manufacturer. In the case of Lowrance sonars, a file with the .sl2 extension is created during recording. To process files of this format, it is recommended to use the SonarViewer program (figure 4).
Figure 4 - SonarViewer software workspace: (a) second-type sonar echogram; (b) structure scanner sonogram
This application allows the exploration of data obtained from second-type sonars and more complex Lowrance fourth-type modifications. SonarViewer provides the ability to convert and export data from an .sl2 file to a tabular .csv format or a text .txt format.
Primary data are subject to further processing: incorrect values are discarded, feet are converted to meters if necessary, and the depth of the sonar sensor is added to the survey data. Information from the recorders is synchronized in time and space with the survey data, after which all materials are brought to a single level. The next stage involves creating a vector layer based on the processed tabular data.
Tabular information is imported into the GIS package project and converted into a point vector layer. In the context of this article, we will consider importing data into Global Mapper. For this software, it is sufficient to prepare a table file with an .xlsx, .txt, .csv, or other extension, then specify the file parameters (projection, layer geometry, coordinate format, etc.), and save the imported material in the selected vector format in the specified coordinate system (for example, .shp) (figure 5).
a b
Figure 5 - Vector point layer based on large-scale survey results (a) and small-scale (b)
For navigable sections of rivers, an up-to-date plan of the channel in contours, brought to the design water level, is required. The design water level (Conditional low water level with a specified reliability according to ГОСТ Р 58731-2019) can be found in navigation charts and sailing directions. Below is a sequence for processing survey materials that allows you to create a plan of the riverbed in contours.
Calculate the cut-off level (the excess of the working water level above the design level), using information about the working water level in the area. In this simple case, it is assumed that the cut-off at the upper and lower boundaries of the work area is the same. Create a shoreline layer (linear). The shoreline layer should contain a depth field, the value of which for objects is zero (corresponds to the zero depth line, i.e., the waterline). Create a polygonal layer of the site boundary. In the attribute table of the vector layer of survey depth data, find the field containing the depths and convert them to meters if necessary, calculate the depths corresponding to the design level. Perform interpolation of depths corresponding to the design level, using depth surveys, the shoreline, and the boundaries of the area (figure 6).
Figure 6 - Performing interpolation using the Topo To Raster method in ArcGIS Desktop and the result of the interpolation
Build a linear contour layer within the channel boundary. Perform smoothing and manual adjustment of contours. The design of the riverbed plan may include adding labels, a scale bar or numerical scale, a north arrow or coordinate grid, a legend and map (plan) title, information about the coordinate system, the date of the survey, and the working level, cut-offs. The numerical scale is used when preparing a plan for printing in a specified format. For using the plan in electronic form, it is recommended to use a linear scale.
A riverbed plan in isohypses (absolute elevation marks) is usually required for construction and operation areas of coastal structures connected to the water area (bridges, piers, water intakes, etc.). Creating a riverbed plan in isohypses (building a digital model of the riverbed relief) is also based on the array of survey work data and can be done in two ways. First, converting the array of depth survey data to absolute elevations by any means, then repeating the procedure described above.
Figure 7 - Riverbed plan in contours (example)
The second path is performed using GIS tools and involves continuing work with the riverbed plan in contours (figure 7). Using the array of depth surveys, or based on corrected contours, perform depth interpolation. The resulting raster depth layer will be used as the primary dataset for channel relief. Build a raster model of the sloping water surface at the design level using data on the design water level at the boundaries of the river section. Construct a digital model of the riverbed relief in absolute elevations by comparing surfaces (raster calculator). This will be a raster layer representing a field of difference values between the water surface model at the design level and the depth layer at the design level. Build a riverbed plan in isohypses (contours), adjust isolines if necessary.
Conclusion. In conclusion, it can be emphasized that the development and use of an effective methodology for working with an echo sounder is a key factor for obtaining accurate and reliable data on the depths and geometry of water bodies. This note represents a summary of modern approaches and tools used in applied hydrographic research using echo sounders.
Understanding and applying the echo sounder methodologies described in the article will enable specialists in the field of hydrography and related disciplines to successfully solve depth probing tasks, as well as increase the efficiency and safety of navigation, water construction, and other works related to the
study and use of water resources. In the future, with the development of technologies and the increasing need for more accurate and detailed data on water bodies, further improvement of echo sounder methodologies is expected, as well as integration with other geophysical and hydrological research methods.
This will enable the creation of increasingly accurate and informative hydrographic models reflecting the dynamics and features of water bodies at various scales and with different degrees of detail.
REFERENCES
[1] ГОСТ Р 58731-2019. Inland water transport. Hydrographic works. Terms and definitions. Available at: https://docs.cntd.ru/document/1200170106
[2] СП-104-97 "Engineering and geodetic surveys for construction. Part III. "Engineering and hydrographic works in engineering surveys for construction" / State Construction Committee of Russia. Moscow: Production and Research Institute for Engineering Surveys in Construction (FSUE "PNIIIS") of the State Construction Committee of Russia, 2004.
[3] СП РК 1.02-101-2014 Engineering and geodetic surveys for construction. Basic provisions, 2014.
[4] Korotkin I.M., Nefedov P.M. Historical sketch of the development of domestic echo sounding. Leningrad: Publishing house 9 NII MO USSR, 1985.
[5] Lavrentyev A.V., Bogdanovich M.L., Lysenko K.Y. How many fathoms under the keel? Development of depth measuring tools: from an ordinary pole to a modern navigational echo sounder // Military-Historical Journal. 2007. N 6. P. 61-65.
[6] Lowrance. (2021). Lowrance HDS Carbon User Reference Guide. Retrieved from https://www.lowrance.com/lowrance/type/sonar-gps/hds-carbon/
[7] SonarViewer. (2020). SonarViewer User Manual. Retrieved from https://www.sonarviewer.com/manual/
[8] Blue Marble Geographics. (2021). Global Mapper User's Manual. Retrieved from https://www.bluemarblegeo.com/docs/global-mapper-user-guide.php
[9] Medwin H., Clay C.S. (2021). Fundamentals of acoustical oceanography. Elsevier.
[10] Meyer C.G., Simmonds J.J. (2021). Broadband echosounders: technologies, applications, and challenges // Journal of Marine Science and Engineering, 9(3), 287.
[11] Simmonds E.J., MacLennan D.N. (2005). Fisheries acoustics: theory and practice. John Wiley & Sons.
М. О. Фатхи1, П. Н. Терский2, И. А. Копейкин3
1 Младший научный сотрудник (ФГБУ Государственный океанографический институт им. Н. Н. Зубова, Москва, Российская Федерация)
2 К. г. н., старший научный сотрудник (ФГБУ Государственный океанографический институт им. Н. Н. Зубова, Институт водных проблем Российской академии наук, Москва, Российская Федерация) 3 Инженер (ФГБУ Государственный океанографический институт им. Н. Н. Зубова,
Москва, Российская Федерация)
СОВРЕМЕННЫЕ МЕТОДЫ ГИДРОМЕТРИЧЕСКИХ ИССЛЕДОВАНИЙ: БАТИМЕТРИЧЕСКИЕ РАБОТЫ С ИСПОЛЬЗОВАНИЕМ ЭХОЛОТА
Аннотация. Изучение морфометрии дна водных объектов является важной задачей в ряде отраслей хозяйственной, экономической и иной деятельности, а также в научных исследованиях. В связи с этим необходимы разработка и использование в прикладной гидрографии современных методических решений для выполнения батиметрических работ и обработки полученного материала.
Рассматриваются современные методы работы с эхолотами, охватывающие теоретические и практические аспекты использования этих приборов. Статья представляет обзор классификаций эхолотов, методы выполнения промерных работ в экспедиционных условиях и составления итогового материала в виде таблиц и векторных слоев.
Изложены основные аспекты работы с эхолотами, такие, как выбор оборудования, настройка параметров, проведение промерных работ, обработка и анализ данных, а также их интеграция с геоинформационными системами. Описаны инновационные разработки и технологии, которые способствуют улучшению качества и точности результатов.
Особое внимание уделяется корреляции эхолотов с другими технологиями, такими, как географические информационные системы (GIS). Авторы также рассматривают практические аспекты использования эхолотов в навигации, гидрографии и прочих областях.
Представлен ценный обзор для специалистов в области гидрологии и смежных областей, занимающихся изучением морфометрии дна водных объектов, а также материал для широкого круга читателей, заинтересованных в инновационных технологиях в области акустики и географических информационных систем.
Ключевые слова: промерные работы, геоинформационные системы (ГИС), батиметрия, эхолот, гидростатический самописец (логгер).
М. О. Фатхи1, П. Н. Терский2, И. А. Копейкин3
1 Krni гылыми кызметкер (Н. Н. Зубов атындагы Мемлекетгiк океанографияльщ институты, Мэскеу, Ресей Федерациясы)
2 Г. f. к., ага гылыми кызметкерi (Н. Н. Зубов атындагы Мемлекетпк океанографиялык институты, Ресей гылым академиясынын су мэселелерi институтынын, Мэскеу, Ресей Федерациясы) 3 Инженер (Н. Н. Зубов атындагы Мемлекетпк океанографиялык институты, Мэскеу, Ресей Федерациясы)
ГИДРОМЕТРИЯЛЬЩ ЗЕРТТЕУЛЕРДЩ ЦАЗ1РП ЗАМАНГЫ ЭД1СТЕР1: ЭХОЛОТТЫ ПАЙДАЛАНЫП ЖАСАЛГАН БАТИМЕТРИЯЛЬЩ Ж¥МЫСТАР
Аннотация. Су нысандары тYбiнiн морфометриясын зерттеу, шаруашылык, экономикалык жэне баска да кызмет салаларындагы манызды мiндет болып табылады. Осыган байланысты, батиметриялык ж^мыс-тарды орындау мен алынган материалдарды ендеу Yшiн, колданбалы гидрографияда казiргi замангы эдю-темелiк шешiмдердi жасап жэне оларды пайдалану керек.
Осы к¥рылгыларды колданудын теориялык жэне практикалык аспектiлерiн камтитын эхолоттармен ж^мыс гстеудщ заманауи эдiстерi карастырылады. Макалада эхолоттардыц колданыстагы классифика-цияларына шолу жасалып, экспедициялык жагдайда елшеу ж^мыстарын жYргiзу эдiстерi жэне кестелер мен векторлык кабаттар тYрiндегi корытынды материалдар бершген.
Жабдыкты тандау, параметрлердi реттеу, елшеу ж^мыстарын ж^пзу, деректердi ендеу жэне талдау, сондай-ак оларды геоакпараттык жуйелермен бiрiктiру сиякты эхолоттармен ж^мыс гстеудщ негiзгi аспек-тiлерi карастырылады. Нэтижелердщ сапасы мен дэлдiгiн жаксартуга ыкпал ететiн инновациялык ендеулер мен технологиялар сипатталган.
Эхолоттарды географиялык акпараттык жYЙелер (GIS) сиякты баска технологиялармен бiрiктiруге ерекше назар аударылады. Авторлар сонымен катар навигацияда, гидрографияда жэне баска салаларда эхолоттарды колданудын практикалык аспектшерш карастырады.
Макала су нысандары тубшщ морфометриясын зерттеуге арналган гидрология жэне онымен байла-нысты сала мамандары, сондай-ак, инновациялык технологиялар мен акустика жэне географиялык акпарат-тык жYЙелер саласына кызыгушылык танытатын окырмандардын кен аукымы Yшiн, к¥ВДы шолу жасалган мэлiмет бередi.
ТYЙiн сездер: елшеу ж^мыстары, геоакпараттык жYЙелер (ГАЖ), батиметрия, эхолот, гидростатикалык ездiгiнен жазатын к¥рал (логгер).
