GB2611676A

GB2611676A - Method for constructing depth sounding reference field of large reservoir, and use thereof

Info

Publication number: GB2611676A
Application number: GB2300335.3A
Authority: GB
Inventors: Ren Shi; Wang Hai; Yan Jinbo; Nie Jinhua; Wang Mian; Liu Shizhen; Quan Xiaolong; Tao Ye; Lv Chaonan
Original assignee: Three Gorges Hydrology And Water Resources Survey Bureau; China Three Gorges Corp
Current assignee: Three Gorges Hydrology And Water Resources Survey Bureau; China Three Gorges Corp
Priority date: 2021-03-25
Filing date: 2022-02-28
Publication date: 2023-04-12
Also published as: CN113091852A; WO2022135618A1; CN113091852B

Abstract

A method for constructing a depth sounding reference field of a large reservoir, and the use thereof. The method comprises: site selection for a reference field, wherein in order to meet calibration technology requirements of a plurality of depth sounding devices, it is necessary to arrange reference points (SJD1, SJD2) in various forms, and a reference plane; construction of the reference points (SJD1, SJD2); and construction of the reference plane. Research on a depth sounding error, a positioning error and a water level correction error can be performed on the basis of the depth sounding reference points (SJD1, SJD2), comprising influences of a nominal precision of a depth sounder, a depth sounding mode, an actual sounding depth and a dynamic draft, influences of a positioning precision, a GNSS data update rate, a differential method, etc., and influences of a water level estimation model, etc. Research on a depth sounding environment error and research on a GNSS three-dimensional water channel depth sounding precision can be performed on the basis of the depth sounding reference plane, comprising research on influences of a wave effect, a positioning center deviation effect, a single-beam depth sounding attitude effect, a depth sounding delay effect, a ship speed effect, a beam angle effect, a coupling effect, a water body characteristic, a depth sounding sampling frequency and smoothing mode, a sound ray tracking, depth sounding point cloud precision analysis of a multi-beam depth sounding system, etc.

Description

METHOD FOR CONSTRUCTING DEPTH SOUNDING REFERENCE FIELD OF LARGE RESERVOIR, AND USE THEREOF

TECHNICAL FIELD

The present disclosure belongs to the technical field of sounding of reservoirs, and in particular relates to a construction method and application of a sounding datum field for a large-scale reservoir.

BACKGROUND

Current issues in sounding: (1) After the impoundment of a reservoir, an influence of a sounding environment on sounding precision tends to be complex.

The average operating water depth obtained through depth surveying of inland water bodies in China is generally less than 50 m, and large water depth surveying is generally found in marine surveying. Due to different operating environments (water depth, water temperature, flow field, wave, and salinity) and different precision requirements, observation methods and indicators to follow are not suitable for the inland water bodies. After the impoundment of the Three Gorges reservoir and important upstream reservoirs, the water depth increases exponentially. For example, after the impoundment and application of the Three Gorges Project and the Xiluodu Water Control Project on the Jinsha River, the water depth of the reservoir section in front of a dam and the water depth before the impoundment have increased by 120 m and 300 m respectively. In addition, the fluidity of the water body is reduced, which leads to water temperature stratification of the water bodies in the upper and lower layers due to insufficient exchange. Especially, the water body in a perennial backwater area of the reservoir has more obvious water temperature stratification with seasonal changes. The difference between the surface and bottom water temperatures of the water body of the reservoir section in front of the Xiluodu dam in summer is nearly 10 DEG C. The difference will lead to the change of sound velocity and the refraction of sound rays, which will seriously influence the sounding precision of the canyon reservoir.

(2) After the impoundment of the reservoir, the sounding precision of conventional sounders is limited under the condition of large water depth.

With the completion and application of the Three Gorges reservoir and the important upstream reservoirs, the water depth has increased significantly compared with that before the impoundment and application. The precision of the conventional sounder is significantly influenced by the attitude of a surveying ship, a delay effect, a beam-width effect and the like under the condition of large water depth. At present, only the operating velocity of the surveying ship has been reduced. The velocity of a topographic observation ship in the Three Gorges reservoir area has been reduced to 4 lu) (2 m/s). Moreover, in order to ensure the stability of the results, a section needs to be continuously observed for two times, and finally data with better precision are taken, which severely limits the operating efficiency. Due to a series of problems, for example, the influence of the attitude of the surveying ship cannot be completely eliminated, the time synchronization of sounding and positioning signals is difficult, and the beam-width effect is difficult to correct, especially the inclination of near-shore slope is mostly between 0 and 30 degrees, the inclination of some reservoir sections is more than 30 degrees, the slope of special parts even reaches 90 degrees, and the beam-width effect is further amplified, at present, the observation precision of large water depth has always been maintained within 1% of the relative water depth, which is difficult to break through.

(3) A datum is lacked for a high-precision sounding technology research under the condition of large water depth.

The biggest problem in the research on the precision of underwater topographic observation is that the underwater topography is constantly changing under the action of water flow, and cannot have a stable true value like the onshore topographic observation, which can be used as a datum for the research on the sounding technology. Therefore, repeated observation is carried out to assess the underwater sounding precision according to the current "Specifications for waterway survey" (5L257-2017), and low underwater sounding precision assessed through the repeated observation is analyzed and counted. Due to the lack of high-precision and stable underwater datum points (background topography), the underwater sounding precision belongs to the concept of relative precision, and the absolute precision is difficultly observed and counted, which further analyzes the factors influencing the sounding precision and creates obstacles for a targeted research.

SUMMARY

In order to achieve the above technical effect, the object of the present disclosure is achieved as follows: a construction method of a sounding datum field for a large-scale reservoir includes the following steps: Step I, site selection of the datum field: in order to meet the technical requirements for calibration of various sounding equipment, various forms of datum points and datum plates need to be laid out; Step 2, datum point construction; and Step 3, datum plane construction.

In Step I, the datum points include a flat cement ground datum point and a suspended cavity datum point; and the datum planes include a flat datum plane, a slope datum plane and a steep slope datum plane.

The specific process of the datum point construction in Step 2 is as follows: Step 2.1, for the flat cement ground datum point, the construction process is as follows: a square area is selected at the turning point in the downstream direction of a separation levee and between a datum section GLO1 and a datum section GL02, five cement nails are used to fix four corner points and a center point of the square area, the positions of the cement nails are taken as the datum points, the three-dimensional coordinates of the datum points are surveyed by adopting an RTK (Real Time Kinematic) method, and the elevations of the datum points are surveyed by adopting a reverse measuring method of a total station; and Step 2.2, for the suspended cavity datum point, the construction process is as follows: two datum points are selected as a datum point SJD1 and a datum point SJ D2 at the top of a construction area, and suspended transverse tubular acoustic reflectors are fixedly installed at the positions where single datum points are positioned through steel brackets.

The suspended transverse tubular acoustic reflector adopts a round seamless steel pipe with a diameter of D, the wall thickness thereof is not less than 3 mm, both ends of the round seamless steel pipe are fully welded and sealed with round steel plates with the same thickness, and a water tightness test is carried out.

The steel bracket is formed by splicing and welding the steel pipes, the plane of the steel bracket is a forward walking area, supporting feet are fixed at the positions of four apex angles and a center point of the steel bracket, the bottom ends of the supporting feet are provided with flange plates, the flange plates are fixed inside holes through expansion screws, and after the supporting feet are fixed, the holes are filled up with cement.

A stainless steel nameplate is made for each datum point and fixed to the steel bracket In Step 2.2, after the construction of the datum point SIDI and the datum point SJD2 is completed, the plane positions of the four apex angles and the center of a mark surface of the steel bracket are accurately surveyed by adopting the RTK method, the elevation is surveyed by adopting the reverse measuring method of the total station, the height difference between the four vertex angles and the height difference d between the center points of the mark surfaces of the two steel brackets are checked through the precision observation of fourth-grade leveling, so as to check the precision of the ranging trigonometric leveling, and a topographic point bitmap of the datum point SJD1 and the datum point SJD2 is finally generated.

The specific process of the datum plane construction in Step 3 is as follows: Step 3.1, for the flat datum plane, the construction process is as follows: the flat datum plane includes three datum sections, and the datum section is surveyed by adopting a land surveying method to obtain datum section results, which specifically includes the following steps: Step 3.1.1, mapping control layout: a total of six mapping control points are laid out on the flat datum plane, namely GLO1 to GL06, which are used as the section breakpoints of the datum sections 001 to 003, the plane coordinates are all surveyed by adopting the RTK method, and the elevation is surveyed by adopting the reverse measuring method of the total station; and Step 3.1.2, datum section surveying: the datum sections 001 to 003 are surveyed by adopting the reverse measuring method of the total station, and the point distance is controlled to 5 m; Step 3.2, for the slope datum plane, the construction process is as follows: the slope datum plane and the datum section are surveyed at a scale of 1:500 by adopting the land surveying method to obtain a local topographic map of the slope datum plane and datum section results, which specifically includes the following steps: Step 3.2.1, mapping control layout: a total of three mapping control points are laid out, namely SW01, SW02 and SW03, the plane coordinates of the three mapping control points are all surveyed by adopting the RTK method, the elevations of SW01 and 5W02 are subjected to transfer survey from an elevation citation point HDQX03 by adopting a fourth-grade leveling round-trip surveying method, and the elevation of 5W03 is surveyed by adopting the reverse measuring method of the total station; Step 3.2.2, datum section surveying: the datum section is surveyed by adopting the reverse measuring method of the total station, and the point distance is controlled to 5 m and Step 3.2.3, datum plane surveying: the local topography of the datum plane is surveyed at a scale of 1:500 by adopting the reverse measuring method of the total station; Step 3.3, for the steep slope datum plane, the construction process is as follows: the datum field includes a steep slope datum plane and a datum section, and the datum plane and the datum section are surveyed at a scale of 1:500 by adopting the land surveying method to obtain a topographic map of the datum plane and datum section results, which specifically includes the following steps: Step 3.3.1, mapping control layout: three mapping control points are laid out on the datum plane, the plane coordinates are surveyed by adopting the RTK method, and the elevation is surveyed by adopting the reverse measuring method of the total station; and Step 3.3.2, surveying of the datum plane and the datum section: the three-dimensional coordinates of the datum section and a topographic point of the datum plane are surveyed by adopting the reverse measuring method of the total station, and section results of the section and a topographic map of the steep slope datum plane are finally obtained.

A using method of the datum field constructed by the construction method of the sounding datum field for the large-scale reservoir includes the following usages: first, a research of static sounding based on a datum point; and second, a research of dynamic sounding based on a datum plane.

The research of static sounding based on the datum point specifically includes the following aspects: (1) sounding precision analysis of sounders of different types: fixed-point sounding is carried out by adopting echo sounders of different types and produced by different manufacturers, at least 30 valid data are collected by each echo sounder, and the nominal precision and the actual sounding precision of the sounders of different types are analyzed based on the data collected during the test; (2) sounding robust analysis of different sounders: sounding data are collected by adopting different sounders in a way that the ship velocity is not fixed, and robust analysis is carried out by adopting four different methods; and during the test, a planning line is preset, and an attitude sensor is added to the system, Auto is selected for the Ping Rate of the sounder, the gain is fixed, the sounder is adopted for high-frequency sounding, at least 60 valid data are collected, and artificial sounding correction is not carried out before valid data analysis; (3) analysis of fixed-point GNSS three-dimensional waterway sounding precision: fixed-point sounding is carried out by adopting a conventional tidal observation surveying method and an RTK non-tidal observation method, and 20 to 30 valid data are collected; and observation is carried out when the water level is stable, the stability and observation precision of the RTK non-tidal observation surveying are tested, the sensitivity of the RTK non-tidal observation surveying to water surface fluctuations is tested by adopting an artificial water surface fluctuation method, and surveying errors of different sounding methods are analyzed based on the data collected during the test; (4) analysis of an influence of gains on sounding precision: surveying is carried out with four different gains of Auto, low, medium and high by two different sounders, a total of eight groups of data are collected, and at least 20 valid data are collected in each group; and the sounding precision of sounders of different types under different gain conditions is analyzed base on the data collected during the test, (5) analysis of an influence of different sound velocities on sounding precision: sounding is carried out by adopting a certain sounder at the standard sound velocity, sounding correction is carried out by adopting sound velocity calculation formulas in the "Code for waterway survey" and "Specifications for hydrographic survey" and at a total of three different stratified sound velocities in stratified sound velocities actually surveyed by a sound velocity profiler during data post-processing, and at least 20 valid data are collected during the test; and the influence of different sound velocity formulas on the sounding precision is analyzed based on the data collected during the test; (6) analysis of an influence of adjusting a sound velocity on sounding precision: a certain sounder is used to actually survey the depths of comparison panels, when the depths of the two comparison panels are inconsistent, the sound velocity of the sounder is adjusted until the water depths of the two comparison panels are consistent, then the sound velocity is fixed on the datum point for a sounding precision test, and at least 20 valid data are collected during the test; and the sounding precision during the test of adjusting the sound velocity of the sounder to carry out sounding is analyzed based on the data collected during the test; and (7) analysis of positioning errors of different positioning methods: the positioning errors of different positioning methods are analyzed through GGA and GGK positioning data by adopting the positioning methods of a CORS (Continuously Operating Reference Stations) and a reference station set up autonomously, and when the reference station is set up autonomously, a known control point with a plane level not lower than level D and an elevation level not lower than level 5 is selected for the datum station, and at least 20 sets of data are surveyed by Hypack software on a land self-made simulated slipway at an update rate of 10 Hz of a Trimble R10 GNSS (Global Navigation Satellite System) for positioning The research of dynamic sounding based on the datum plane specifically includes the following aspects: (1) precision analysis of single-beam coupling effect sounding: a combined test is carried out at the longitudinal section of the datum plane by adopting different sounders under the conditions of non-integrated and integrated attitude sensors of a single-beam sounding system at three different ship velocities and different GNSS data update rates, one round-trip observation is carried out on a datum longitudinal section at a scale of 1:500 during the test for sounding, the distance between observation points is set as 5 m, the sound velocity profiler carries out the sound velocity profile at the datum plane, and the influence of an attitude, a positioning center deviation effect, a single-beam sounding attitude effect, a ship velocity effect, a beam-width effect and a coupling effect on sounding is researched based on the data collected during the test; (2) analysis of the delay effect and a position and water depth synchronization algorithm: sounding is carried out on the datum longitudinal section at the longitudinal section of the slope datum plane through the data post-processing delay correction of a single-beam sounding system and by a sounder adopting the position and water depth synchronization algorithm, and the sounding delay effect and the correction effect are analyzed based on the data collected during the test; (3) analysis of an influence of a sounding sampling frequency on sounding: one round-trip observation is carried out on the datum longitudinal section at the longitudinal section of the slope datum plane under the conditions of a fixed gain, a high frequency of the sounder and a baud rate of 19,200 Hz at a scale of 1:500 at different Ping Rates, the distance between the observation points is set as 5 m, the attitude data are collected during surveying, the ship velocity is 4 to 5 knots, the Ping data statistical analysis is carried out during data analysis, that is, the average value of the water depth data before and after calibration is compared with the calibrated water depth data, and the influence of the sounding sampling frequency on sounding is analyzed based on the data collected during the test; (4) precision analysis of dynamic multi-beam sounding: different multi-beam sounding systems are used to carry out one round-trip sweeping survey at the longitudinal sections of the datum planes at the velocity of conventional surveying, and the sounding point cloud precision analysis of the multi-beam sounding systems is carried out based on the data collected during the test, and (5) precision analysis of GNSS three-dimensional waterway sounding: one round-trip observation is carried out by a GNSS + single-beam integrated sounding system on the datum longitudinal section at the longitudinal section of the datum plane at the velocity of conventional surveying at a scale of 1:500, the distance between the observation points is set as 5 m, and the GNSS three-dimensional waterway sounding precision can be analyzed based on the data collected during the test.

The present disclosure has the following beneficial effects: 1. Precision sounding datums are provided.

High-precision large water depth sounding has always been a technical problem at home and abroad. With the impoundment and application of the Three Gorges reservoir and large upstream reservoirs, the maximum water depth exceeds 200 m. The stratified phenomenon of water temperature caused by large water depth, the attitude of the surveying ship, the change of dynamic draft, the beam-width effect of the sounder, the sounding time delay and the surge effect have different degrees of influences on the precision of large water depth sounding, which is very complex. More importantly, because the underwater topography is constantly changing under the influence of water flow, a stable "true value" is difficultly found as a datum to assess the precision.

The construction of the datum field is carried out during the drawdown period of the reservoir, including site selection, construction, plane position surveying and elevation surveying. The most key thing is that the datum field is surveyed by adopting a high-precision land topographic surveying method, which completely avoids a series of sounding influencing factors such as complex water flow environment, topographic influencing factors, influencing factors of the sounding precision of an echo sounder, and positioning precision influencing factors under dynamic conditions. The datum points and the datum planes can be seen and felt. Observation instruments has higher precision than underwater surveying in both plane positioning and elevation surveying, and the observation results are reliable, which can be used as the "true value" of underwater topographic surveying.

2. A basis is provided for the research on the observation and control indicators of sediment erosion and deposition in the Three Gorges reservoir and the large upstream reservoirs.

With the impoundment and application of the Three Gorges reservoir and the large upstream reservoirs, the water depth has increased significantly, the sediment has been greatly reduced, and the relationship between water and sediment and the characteristics of erosion and deposition have also changed. In the past, due to the large amount of sediment erosion and deposition between observations, the current control indexes of erosion and deposition observation can be used to effectively reveal the changes in erosion and deposition. Now, due to the continuous improvement of observation conditions and observation requirements, how to further optimize the observation layout, observation technology, precision control and other indicators of reservoir sediment erosion and deposition observation, so as to better serve the reservoir sediment erosion and deposition observation is also a major problem facing us at present. The key to solving this problem is to use the datum field that has been completed to research the influencing factors of precision sounding clearly, and to correct or weaken the influencing factors. In this process, the best time and the best sounding technology and method for the observation of erosion and deposition in the Gorge reservoir are gradually summarized, and the precision control indexes suitable for the Three Gorges reservoir area is optimized.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will be further described below with reference to the accompanying drawings and embodiments FIG. I is a layout diagram of high-precision datum points and datum planes of the Three Gorges reservoir in an embodiment of the present disclosure.

FIG. 2 is a bitmap of a datum point of a separation levee in an embodiment of the present disclosure.

FIG. 3 is a structural diagram of a suspended cavity datum point in an embodiment of the present disclosure.

FIG. 4 is a pattern of a datum point nameplate in an embodiment of the present disclosure, FIG. 5 is a layout diagram of a datum point of Xikou oflingjiang in an embodiment of the present disclosure.

FIG. 6 is a bitmap of a datum plane at a separation levee crown in an embodiment of the present disclosure.

FIG. 7 is a sectional view of a datum plane of Shawan in an embodiment of the present disclosure FIG. 8 is a local topographic map of a datum field of Wuxiangmiao in an embodiment of the present disclosure FIG. 9 is a sectional view of a datum plane of Wuxiangmiao in an embodiment of the present disclosure

DETAILED DESCRIPTION OF THE EMBODIMENTS

The embodiments of the present disclosure will be further described below with reference to the accompanying drawings.

Example 1:

In this embodiment, the construction of the datum field of the Three Gorges reservoir is taken as an example to describe the specific implementation process of the present disclosure A construction method of a sounding datum field for a large-scale reservoir includes the following steps: The high-precision underwater datum field of the Three Gorges reservoir includes datum points and datum planes, which are located at the separation levee crown at the upstream of the Three Gorges, Shawan (Three Gorges Maritime Safety Administration), Wuxiangmiao (a water gauge for a water course), and Xikou of Jingjiang, as shown in FIG. 1. Construction is carried out at the flood control level (145 m), and the land surveying method is used to carry out high-precision reservoir bank topography and section surveying and datum point observation in the section from 145 m to 175 m, so as to form a high-precision and high-resolution background topography and systematic underwater datum values. After the impoundment, a relevant sounding error research is carried out.

Step 1, Site selection of the datum field: in order to meet the technical requirements for calibration of various sounding equipment, various forms of datum points and datum planes are laid out in the datum field of the Three Gorges reservoir area; and the datum points include a flat cement ground datum point and a suspended cavity datum point, and the datum planes include a flat datum plane, a slope datum plane and a steep slope datum plane.

(I) Datum point 0 The flat cement ground datum point is laid out at the separation levee crown at the upstream of a Three Gorges dam, and a 5 m * 5 m square datum point is laid out on the flat concrete ground at the separation levee crown 0 The suspended cavity datum point is laid out at the top of a small island at the entrance of Xikou of Jingji ang, and two 3 m * 3 m datum points are laid out by burying an enhanced steel tubular acoustic reflector. (2) Datum plane 0 The flat datum plane is selected at the separation levee crown at the upstream of the Three Gorges dam, and three datum sections are laid out on the flat cement ground at the separation levee crown.

0 The slope datum plane is selected at Shawan (Three Gorges Maritime Safety Administration), a datum section is laid out along the Xiahe road, the ground is made of cement, and the overall slope is about 5.69 degrees.

C) The steep slope datum plane is selected at Wuxiangmiao (a water gauge for a water course), a datum section is laid out along a slope protection surface, the ground is mainly made of cement, arid the overall slope is about 40 degrees.

Step 2, Datum point construction: Step 2.1, construction of the flat cement ground datum point The datum point of the separation levee is located at the turning point in the downstream direction of the separation levee, a 5 m * 5 m square area is selected between the datum sections GLOI and GL02, five cement nails are used to fix four corner points and a center point of the datum point, the three-dimensional coordinate of the datum point is surveyed by adopting an RTK method, and the elevation of a characteristic point is surveyed by adopting a reverse measuring method of a total station. For details, see FIG. 2 for a bitmap of a datum point of a separation levee.

Step 2.2, construction of a suspended cavity datum point of Xikou of Jingjiang (1) The datum points of Xikou of Jingjiang are constructed at the top of the small island in an outer river of Xikou of Jingjiang, and include two datum points (SJ D I and SJD2) A single datum point includes multiple groups of suspended transverse tubular acoustic reflectors (hereinafter referred to as "reflectors") and steel brackets, and the pattern is shown in FIG. 3 (2) The reflector adopts a round seamless steel pipe with a diameter of 10 cm, the wall thickness thereof is not less than 3 mm, both ends of the reflector are fully welded and sealed with steel plates with the same thickness in a cross-section shape, and a water tightness test is carried out. A 3 m * 3 m mark surface is assembled.

(3) The steel bracket is made of a steel pipe with a wall thickness of 5 mm and a diameter of 10 cm, and the both ends do not need to be sealed. A flange plate is welded at one end of the steel pipe. A hole with a depth of more than 30 cm is dug on a rock, the bottom of the hole is drilled and expansion screws are driven, and a nut is welded after the flange plates are connected. Finally, the hole is filled up with cement (4)A stainless steel nameplate is made for each datum point, a name is written for the datum point, and the pattern is shown in FIG. 4. A warning sign of "Survey Mark, No Damage" is set up and welded in a conspicuous place.

(5) The RTK method is used to accurately survey the plane positions of four corner points and a mark center of the mark surface, and the elevation is surveyed by adopting the reverse measuring method of the total station. The height difference between the four corner points and the height difference between the center points of the two mark surfaces are checked through the precision observation of fourth-grade leveling, so as to check the observation precision of the ranging trigonometric leveling, and a topographic point bitmap of the datum point 1 and the datum point 2 of the Three Gorges is finally generated. See FIG. 5 for a layout diagram of a datum point of Xikou of Jingjiang.

Step 3, Datum plane construction: Step 3.1, Construction of a flat datum plane, that is, a datum plane at a separation levee crown The datum plane of the separation levee is a flat datum plane which includes three datum sections. The datum section is surveyed by adopting a land surveying method, and the datum section results are obtained. See FIG. 6 for a bitmap of a datum plane at a separation levee crown.

(1) Mapping control layout: a total of six mapping control points are laid out on the datum plane of the separation levee, namely GLO1 to GLOG, which are used as the section breakpoints of the datum sections GO1 to G03. The plane coordinate is surveyed by adopting the RTK method, and the elevation is surveyed by adopting the reverse measuring method of the total station.

(2) Datum section surveying: datum sections GO1 to G03 are surveyed by adopting the reverse measuring method of the total station, and the point distance is controlled to 5 m.

Step 3.2, Construction of a slope datum plane, that is, a datum plane of Shawan The datum plane of Shawan includes a slope datum plane and a datum section. The datum plane and the datum section are surveyed at a scale of 1:500 by adopting the land surveying method to obtain a local topographic map of the datum plane and datum section results.

(1) Mapping control layout: a total of three mapping control points are laid out on the datum plane of Shawan, namely SW01, SW02 and SW03, the plane coordinates of the three mapping control points are all surveyed by adopting the RTK method, the elevations of SW01 and 5W02 are subjected to transfer survey from an elevation citation point HDQX03 by adopting a fourth-grade leveling round-trip surveying method. The elevation of SW03 is surveyed by adopting the reverse measuring method of the total station.

(2) Datum section surveying: a datum section SW01 (section endpoints SW01 and SW03) are surveyed by adopting the reverse measuring method of the total station, and the point distance is controlled to 5 m.

(3) Datum plane surveying: a local topography of the datum plane is surveyed at a scale of 1:500 by adopting the reverse measuring method of the total station.

The observation range of the elevation of the slope datum plane of Shawan covers the interval from 146 m to 177 m, and the overall slope is 5.69 degrees, as shown in FIG. 7. The large-scale midline longitudinal section (1:500) and a 5 m * 5 in grid topography are observed.

Step 3.3, Construction of a steep slope datum plane, that is, a datum plane of Wuxiangmiao The datum field of Wuxiangmiao (a water gauge for a water course) includes a steep slope datum plane and a datum section. The datum plane and the datum section are surveyed at a scale of 1:500 by adopting the land surveying method to obtain a topographic map of the datum plane and datum section results.

(1) Mapping control layout: three mapping control points are laid out on the datum plane of Wuxiangmiao, namely a Wuxiangmiao stage gauging station checkpoint 20, a Wuxiangmiao stage gauging station checkpoint 21 and W S01, the plane coordinates are surveyed by adopting the RTK method, the elevations of the Wuxiangmiao stage gauging station checkpoint 20 and the Wuxiangmiao stage gauging station checkpoint 21 are known, and are at Grade 3, and the elevation of WS01 is surveyed by adopting the reverse measuring method of the total station.

(2) Surveying of the datum plane and the datum section: the three-dimensional coordinates of the datum section WX01 (section endpoints WX01L1 and WX01L2) and a topographic point of the datum plane are surveyed by adopting the reverse measuring method of the total station, and the section results of the section WX01 and a topographic map of the steep slope datum plane of Wuxiangmiao are obtained, as shown in FIG. 8.

The observation range of the elevation of the steep slope datum plane of Wuxi angmiao (a water gauge for a water course) covers the interval from 146 m to 177 m, and the slope is about 40 degrees, as shown in FIG. 7. A large-scale datum section (1:500) and a 5 m * S m datum plane topography are observed.

Example 2:

Application of the datum field:

After the flood season, when the water level in the reservoir area reaches 175 m after the impoundment, the sounding test and analysis can be carried out by using the completed datum point and datum plane. A research on sounding errors, positioning errors and water level correction errors can be carried out based on the sounding datum points, including influences on the nominal precision of a sounder, a sounding mode, an actual sounding depth, and a dynamic draft, influences on positioning precision, GNSS data updating rate, a difference method and the like, and influences on a water level reckoning model and the like. A research on sounding environmental errors and a research on GNSS three-dimensional waterway sounding precision can be carried out based on the sounding datum plane, including influences on a wave effect, a positioning center deviation effect, a single-beam sounding attitude effect, a sounding delay effect, a ship velocity effect, a beam-width effect, a coupling effect, water body characteristics, a sampling frequency sounding and smoothing method, sound ray tracking, and analysis of sounding point cloud precision of a multi-beam sounding system.

Based on the sounding test research and analysis of the test field, the large water depth sounding technology is summarized, the precision and reliability of the water depth observation in the reservoir area under the condition of large water depth are improved, and a complete set of observation technology and precision control indicators suitable for the large water depth surveying of the Three Gorges reservoir and the large upstream reservoirs are proposed.

First: A research on static sounding based on datum point (1) Sounding precision analysis of sounders of different types. fixed-point sounding is carried out by adopting echo sounders of different types and produced by different manufacturers, at least 30 valid data are collected by each echo sounder, and the nominal precision and the actual sounding precision of the sounders of different types are analyzed based on the data collected during the test.

(2) Sounding robust analysis of different sounders: sounding data are collected by adopting different sounders in a way that the ship velocity is not fixed, and robust analysis can be carried out by adopting different methods (four models).

During the test, a planning line is preset, and an attitude sensor is added to the system, Auto is selected for the Ping Rate of the sounder, the gain is fixed, the sounder is adopted for high-frequency sounding, at least 60 valid data are collected, and artificial sounding correction is not carried out before valid data analysis.

(3) Analysis of fixed-point GNSS three-dimensional waterway sounding precision: fixed-point sounding is carried out by adopting a conventional tidal observation surveying method and an RTK non-tidal observation method (by a seven-parameter transformation model), and 20 to 30 valid data are collected, and observation is carried out when the water level is stable, the stability and observation precision of the RTK non-tidal observation surveying are tested, the sensitivity of the RTK non-tidal observation surveying to water surface fluctuations is tested by adopting an artificial water surface fluctuation method, and surveying errors of different sounding methods are analyzed based on the data collected during the test (4) Analysis of an influence of gains on sounding precision: surveying is carried out with four different gains of Auto, low, medium and high by two different sounders, a total of eight groups of data are collected, and at least 20 valid data are collected in each group; and the sounding precision of sounders of different types under different gain conditions is analyzed base on the data collected during the test.

(5) Analysis of an influence of different sound velocities on sounding precision: sounding is carried out by adopting a certain sounder at the standard sound velocity (1,460 m/s), sounding correction is carried out by adopting sound velocity calculation formulas in the "Code for waterway survey" and "Specifications for hydrographic survey" and at a total of three different stratified sound velocities in stratified sound velocities actually surveyed by a sound velocity profiler during data post-processing, and at least 20 valid data are collected during the test; and the influence of different sound velocity formulas on the sounding precision is analyzed based on the data collected during the test.

(6) Analysis of an influence of adjusting a sound velocity on sounding precision: a certain sounder is used to actually survey the depths of comparison panels, when the depths of the two comparison panels are inconsistent, the sound velocity of the sounder is adjusted until the water depths of the two comparison panels are consistent, then the sound velocity is fixed on the datum point for a sounding precision test, and at least 20 valid data are collected during the test; and the sounding precision during the test of adjusting the sound velocity of the sounder to carry out sounding is analyzed based on the data collected during the test.

(7) Analysis of positioning errors of different positioning methods: the positioning errors of different positioning methods are analyzed through GGA and GGK positioning data by adopting the positioning methods of a CURS (Continuously Operating Reference Stations) and a reference station set up autonomously.

When the reference station is set up autonomously, a known control point with a plane level not lower than level D and an elevation level not lower than level 5 is selected for the datum station, and at least 20 sets of data are surveyed by Hypack software on a land self-made simulated slipway at an update rate of 10 Hz of a Trimble R10 GNSS (Global Navigation Satellite System) for positioning Second: A research of dynamic sounding based on a datum plane (1) Precision analysis of single-beam coupling effect sounding: a combined test is carried out at the longitudinal section of the datum plane by adopting different sounders under the conditions of non-integrated and integrated attitude sensors of a single-beam sounding system at three different ship velocities (low (2 knots), medium (4 knots) and high (6 knots)) and different GNSS data update rates (5 Hz, 10 Hz and 20 Hz), one round-trip observation is carried out on a datum longitudinal section at a scale of 1:500 during the test for sounding, the distance between observation points is set as 5 m, the sound velocity profiler carries out the sound velocity profile at the datum plane, and the influence of an attitude, a positioning center deviation effect, a single-beam sounding attitude effect, a ship velocity effect, a beam-width effect and a coupling effect on sounding is researched based on the data collected during the test.

Table I. Combination method of dynamic survey of single-beam datum plane Serial Test site Attitude sensor Test Ship ONSS data Remark number integration instrument velocity update condition frequency Separation levee Internal Sounder I 2 knots 10 Hz Round-trip erown/Shaivan/W integration/external observation uxiangmiao integration 4 knots 10 H7 6 knots 10H7 Sounder 2 2 knots 10 Hz 4 knots 10 Hz 6 knots 10 Hz 2 knots 10 Hz 4 knots 10 Hz 6 knots 10 Hz Serial Test site Attitude sensor Test Ship (MSS data Remark number integration instrument velocity update condition frequency 2 Separation levee Internal Sounder n 2 knots 5 Hz erown/Shawan/W integration/external uxiangm iao integration Hz Hz 4 knots 5 Tft H7 H7 6 knots 5 Hz Hz Hz Remark: All internal or external attitude sensors of the sounding system collect data synchronously during field survey, and data with attitude sensor and data without attitude sensor are separately analyzed during internal data processing.

(2) Analysis of a delay effect and a position and water depth synchronization algorithm: sounding is carried out on the datum longitudinal section at the longitudinal section of the slope datum plane through the data post-processing delay correction of a single-beam sounding system and by a sounder adopting the position and water depth synchronization algorithm, and the sounding delay effect and the correction effect are analyzed based on the data collected during the test (3) Analysis of an influence of a sounding sampling frequency on sounding: one round-trip observation is carried out on the datum longitudinal section at the longitudinal section of the slope datum plane under the conditions of a fixed gain, a high frequency of the sounder and a baud rate of 19,200 Hz at a scale of 1:500 at different Ping Rates (Auto, 1 Ping, 10 Pings, and 20 Pings), the distance between the observation points is set as 5 m, the attitude data are collected during surveying, the ship velocity is 4 to 5 knots, the Ping data statistical analysis is carried out during data analysis, that is, the average value of the water depth data before and after calibration is compared with the calibrated water depth data, and the influence of the sounding sampling frequency on sounding is analyzed based on the data collected during the test.

(4) Precision analysis of dynamic multi-beam sounding: different multi-beam sounding systems are used to carry out one round-trip sweeping survey at the longitudinal sections of the datum planes at the velocity of conventional surveying (about 5 knots), and the sounding point cloud precision analysis of the multi-beam sounding systems is carried out based on the data collected during the test (5) Precision analysis of GNSS three-dimensional waterway sounding: one round-trip observation is carried out by a GNSS + single-beam integrated sounding system on the datum longitudinal section at the longitudinal section of the datum plane at the velocity of conventional surveying (not more than 4 knots) at a scale of 1:500, the distance between the observation points is set as 5 m, and the GNSS three-dimensional waterway sounding precision can be analyzed based on the data collected during the test.

Claims

CLAIMS1. A construction method of a sounding datum field for a large-scale reservoir, comprising the following steps: Step 1, site selection of the datum field: in order to meet the technical requirements for calibration of various sounding equipment, various forms of datum points and datum planes need to be laid out; Step 2, datum point construction, and Step 3, datum plane construction.
2. The construction method of a sounding datum field for a large-scale reservoir according to claim 1, wherein the datum points in Step 1 comprise a flat cement ground datum point and a suspended cavity datum point; and the datum planes comprise a flat datum plane, a slope datum plane and a steep slope datum plane.
3. The construction method of a sounding datum field for a large-scale reservoir according to claim 1, wherein the specific process of the datum point construction in Step 2 is as follows: Step 2.1, for the flat cement ground datum point, the construction process is as follows: a square area is selected at the turning point in the downstream direction of a separation levee and between a datum section GLOI and a datum section GL02, five cement nails are used to fix four corner points and a center point of the square area, the positions of the cement nails are taken as the datum points, the three-dimensional coordinates of the datum points are surveyed by adopting an RTK method, and the elevations of the datum points are surveyed by adopting a reverse measuring method of a total station; and Step 2.2, for the suspended cavity datum point, the construction process is as follows: two datum points are selected as a datum point SJD1 and a datum point SJD2 at the top of a construction area, and suspended transverse tubular acoustic reflectors are fixedly installed at the positions where single datum points are positioned through steel brackets.
4. The construction method of a sounding datum field for a large-scale reservoir according to claim 3, wherein the suspended transverse tubular acoustic reflector adopts a round seamless steel pipe with a diameter of D, the wall thickness thereof is not less than 3 mm, both ends of the round seamless steel pipe are fully welded and sealed with round steel plates with the same thickness, and a water tightness test is carried out.
5. The construction method of a sounding datum field for a large-scale reservoir according to claim 3, wherein the steel bracket is formed by splicing and welding the steel pipes, the plane of the steel bracket is a forward walking area, supporting feet are fixed at the positions of four apex angles and a center point of the steel bracket, the bottom ends of the supporting feet are provided with flange plates, the flange plates are fixed inside holes through expansion screws, and after the supporting feet are fixed, the holes are filled up with cement; and a stainless steel nameplate is made for each datum point and fixed to the steel bracket.
6. The construction method of a sounding datum field for a large-scale reservoir according to claim 3, wherein in Step 2.2, after the construction of the datum point SJD1 and the datum point SJD2 is completed, the plane positions of the four apex angles and the center of a mark surface of the steel bracket are accurately surveyed by adopting an RTK method, the elevation is surveyed by adopting a reverse measuring method of a total station, the height difference between the four vertex angles and the height difference d between the center points of the mark surfaces of the two steel brackets are checked through the precision observation of fourth-grade leveling, so as to check the precision of the ranging trigonometric leveling, and a topographic point bitmap of the datum point. SJD1 and the datum point SJD2 is finally generated
7. The construction method of a sounding datum field for a large-scale reservoir according to claim 1, wherein the specific process of the datum plane construction in Step 3 is as follows: Step 3.1, for the flat datum plane, the construction process is as follows: the flat datum plane comprises three datum sections, and the datum section is surveyed by adopting a land surveying method to obtain datum section results, which specifically includes the following steps: Step 3.1.1, mapping control layout: a total of six mapping control points are laid out on the flat datum plane, namely GLO1 to GL06, which are used as the section breakpoints of the datum sections 001 to G03, the plane coordinates are all surveyed by adopting the RTK method, and the elevation is surveyed by adopting the reverse measuring method of the total station; and Step 3.1.2, datum section surveying: the datum sections GOI to 603 are surveyed by adopting the reverse measuring method of the total station, and the point distance is controlled to 5 m; Step 3.2, for the slope datum plane, the construction process is as follows: the slope datum plane and the datum section are surveyed at a scale of 1:500 by adopting the land surveying method to obtain a local topographic map of the slope datum plane and datum section results, which specifically includes the following steps: Step 3.2.1, mapping control layout: a total of three mapping control points are laid out, namely SW01, 5W02 and 5W03, the plane coordinates of the three mapping control points are all surveyed by adopting the RTK method, the elevations of SW01 and SW02 are subjected to transfer survey from an elevation citation point HDQX03 by adopting a fourth-grade leveling round-trip surveying method, and the elevation of SW03 is surveyed by adopting the reverse measuring method of the total station; and Step 3.2.2, datum section surveying: the datum section is surveyed by adopting the reverse measuring method of the total station, and the point distance is controlled to 5 m; and Step 3.2.3, datum plane surveying: a local topography of the datum plane is surveyed at a scale of 1:500 by adopting the reverse measuring method of the total station; and Step 3.3, for the steep slope datum plane, the construction process is as follows: the datum field comprises a steep slope datum plane and a datum section, and the datum plane and the datum section are surveyed at a scale of 1:500 by adopting the land surveying method to obtain a topographic map of the datum plane and datum section results, which specifically includes the following steps: Step 3.3.1, mapping control layout: three mapping control points are laid out on the datum plane, the plane coordinates are surveyed by adopting the RTK method, and the elevation is surveyed by adopting the reverse measuring method of the total station; and Step 3.3.2, surveying of the datum plane and the datum section: the three-dimensional coordinates of the datum section and a topographic point of the datum plane are surveyed by adopting the reverse measuring method of the total station, and section results of the section and a topographic map of the steep slope datum plane are finally obtained.
8. A using method of the datum field constructed by using the method for constructing the sounding datum field for the large-scale reservoir according to any one of claims 1-7, comprising the following usages: first, a research of static sounding based on a datum point; and second, a research of dynamic sounding based on a datum plane.
9. The using method of the datum field according to claim 8, wherein the research of static sounding based on the datum point specifically comprises the following aspects: (1) sounding precision analysis of sounders of different types: fixed-point sounding is carried out by adopting echo sounders of different types and produced by different manufacturers, at least 30 valid data are collected by each echo sounder, and the nominal precision and the actual sounding precision of the sounders of different types are analyzed based on the data collected during the test; (2) sounding robust analysis of different sounders: sounding data are collected by adopting different sounders in a way that the ship velocity is not fixed, and robust analysis can be carried out by adopting four different methods; and during the test, a planning line is preset, and an attitude sensor is added to the system, Auto is selected for the Ping Rate of the sounder, the gain is fixed, the sounder is adopted for high-frequency sounding, at least 60 valid data are collected, and artificial sounding correction is not carried out before valid data analysis; (3) analysis of fixed-point GNSS three-dimensional waterway sounding precision: fixed-point sounding is carried out by adopting a conventional tidal observation surveying method and an RTK non-tidal observation method, and 20 to 30 valid data are collected; and observation is carried out when the water level is stable, the stability and observation precision of the RTK non-tidal observation surveying are tested, the sensitivity of the RTK non-tidal observation surveying to water surface fluctuations is tested by adopting an artificial water surface fluctuation method, and surveying errors of different sounding methods are analyzed based on the data collected during the test; (4) analysis of an influence of gains on sounding precision: surveying is carried out with four different gains of Auto, low, medium and high by two different sounders, a total of eight groups of data are collected, and at least 20 valid data are collected in each group; and the sounding precision of sounders of different types under different gain conditions is analyzed base on the data collected during the test, (5) analysis of an influence of different sound velocities on sounding precision: sounding is carried out by adopting a certain sounder at the standard sound velocity, sounding correction is carried out by adopting sound velocity calculation formulas in the "Code for waterway survey" and "Specifications for hydrographic survey" and at a total of three different stratified sound velocities in stratified sound velocities actually surveyed by a sound velocity profiler during data post-processing, and at least 20 valid data are collected during the test; and the influence of different sound velocity formulas on the sounding precision is analyzed based on the data collected during the test; (6) analysis of an influence of adjusting a sound velocity on sounding precision: a certain sounder is used to actually survey the depths of comparison panels, when the depths of the two comparison panels are inconsistent, the sound velocity of the sounder is adjusted until the water depths of the two comparison panels are consistent, then the sound velocity is fixed on the datum point for a sounding precision test, and at least 20 valid data are collected during the test; and the sounding precision during the test of adjusting the sound velocity of the sounder to carry out sounding is analyzed based on the data collected during the test; and (7) analysis of positioning errors of different positioning methods: the positioning errors of different positioning methods are analyzed through GGA and GGK positioning data by adopting the positioning methods of a CORS and a reference station set up autonomously; and when the reference station is set up autonomously, a known control point with a plane level not lower than level D and an elevation level not lower than level 5 is selected for the datum station, and at least 20 sets of data are surveyed by Hypack software on a land self-made simulated slipway at an update rate of 10 Hz of a Trimble RIO GNSS (Global Navigation Satellite System) for positioning.
10. The using method of the datum field according to claim 8, wherein the research of dynamic sounding based on a datum plane specifically comprises the following aspects: (1) precision analysis of single-beam coupling effect sounding: a combined test is carried out at the longitudinal section of the datum plane by adopting different sounders under the conditions of non-integrated and integrated attitude sensors of a single-beam sounding system at three different ship velocities and different GNSS data update rates, one round-trip observation is carried out on a datum longitudinal section at a scale of 1:500 during the test for sounding, the distance between observation points is set as 5 m, the sound velocity profiler carries out the sound velocity profile at the datum plane, and the influence of an attitude, a positioning center deviation effect, a single-beam sounding attitude effect, a ship velocity effect, a beam-width effect and a coupling effect on sounding is researched based on the data collected during the test; (2) analysis of a delay effect and a position and water depth synchronization algorithm: sounding is carried out on the datum longitudinal section at the longitudinal section of the slope datum plane through the data post-processing delay correction of the single-beam sounding system and by a sounder adopting the position and water depth synchronization algorithm, and the sounding delay effect and the correction effect are analyzed based on the data collected during the test; (3) analysis of an influence of a sounding sampling frequency on sounding: one round-trip observation is carried out on the datum longitudinal section at the longitudinal section of the slope datum plane under the conditions of a fixed gain, a high frequency of the sounder and a baud rate of 19,200 Hz at a scale of 1:500 at different Ping Rates, the distance between the observation points is set as 5 m, the attitude data are collected during surveying, the ship velocity is 4 to 5 knots, the Ping data statistical analysis is carried out during data analysis, that is, the average value of the water depth data before and after calibration is compared with the calibrated water depth data, and the influence of the sounding sampling frequency on sounding is analyzed based on the data collected during the test; (4) precision analysis of dynamic multi-beam sounding: different multi-beam sounding systems are used to carry out one round-trip sweeping survey at the longitudinal sections of the datum planes at the velocity of conventional surveying, and the sounding point cloud precision analysis of the multi-beam sounding systems is carried out based on the data collected during the test, and (5) precision analysis of GNSS three-dimensional waterway sounding: one round-trip observation is carried out by a GNSS + single-beam integrated sounding system on the datum longitudinal section at the longitudinal section of the datum plane at the velocity of conventional surveying at a scale of 1.500, the distance between the surveying points is set as 5 m, and the GNSS three-dimensional waterway sounding precision may be analyzed based on the data collected during the test.