LSD PQSL Series 2017Hydrographic Survey

Speaker: Sr CHAN Kai‐hong

COMPETENCE AREAS Sounding surveys Hydrographic instrumentation and calibration Satellite positioning and navigation Marine geodesy Marine charting Maritime boundaries Local and international laws of the sea

Hydrographic Survey

Reference Standard: IHO Standard for Hydrographic Surveys (S‐44) 

http://www.iho.int/iho_pubs/standard/S‐44_5E.pdf

Land Information New Zealand: Contract Specifications for Hydrographic Surveys http://www.linz.govt.nz/sea/charts/hydrographic‐standards‐technical‐specifications#sthash.HFzhveS2.dpufhttp://www.linz.govt.nz/sea/charts/hydrographic‐standards‐technical‐specifications

National Oceanic and Atmospheric Administration (NOAA) : Hydrographic Surveys Specifications and Deliverables and Field Procedures Manualhttp://www.nauticalcharts.noaa.gov/hsd/fpm/fpm.htm

Sounding Surveys

Echo Sounding Elements and Concept Errors Calibration 

Position Vertical Datum Horizontal Datum

Sounding Surveys

Echo sounding by Sound Wave  Frequency (High 200k‐350k vs. Low 33k) Single Beam and Multibeam Raw Data vs. Reduced Data Tide, Sound Velocity, Position

Sounding SurveysSounding Elements

Sounding depth = Time x Velocity The velocity of sound in seawater depends on pressure (hence depth), temperature (a change of 1 °C ~ 4 m/s), and salinity (a change of 1 ~ 1 m/s) 

Sounding SurveysSounding Elements

Sounding SurveysSingle Beam Echo Sounding (SBES)

Sounding surveysMultiBeam Echo Sounding (MBES)

Sounding SurveysSounding Errors (Vertical)

MBES measurements MBES beamwidth Vessel’s Motion: Heave, Roll & Pitch Sound speed Draft / Draught Tidal level

Sounding surveysSounding Errors (Horizontal)

MEBS measurements Beamwidth Sound speed Vessel’s Motion: Roll & Pitch Heading GNSS receiver Instrument offset Instrument Angular Misalignment Instrument Latency

How the sounding errors are eliminated: Vessel’s Motion (Pitch, Roll and Heave) ‐ by compensation using motion sensor

Instrument Angular Misalignment (Pitch, Roll and Yaw) ‐by calibration with Patch Test

Instrument Latency ‐ by calibration with Patch Test Draft ‐ by correction with field measurement Sound Velocity ‐ by correction with field measurement

Sounding SurveysSounding Errors

Compensation: Types of Motion Sensor An inertial measurement unit, or IMU, is anelectronic device that measures and reports on acraft's velocity, orientation, and gravitationalforces, using a combination of accelerometers andgyroscopes. (for Multi‐beam Echo Sounder)

Heave Sensor (for Single‐beam Echo Sounder)

Sounding SurveysSounding Errors

Calibration: Patch Test Bar Check

Correction: Use velocity meter to measure the actual sound velocity profile for correction

Sounding SurveysSounding Errors

Types of uncertainty: Total Vertical Uncertainty (TVU) Total Horizontal Uncertainty (THU) Total Propagated Uncertainty (TPU)

Sounding SurveysUncertainties for Depth Accuracy

Bar Check

Hydrographic Instrumentation and Calibration

The calibration or patch test is an essential procedure which consists of determining the composite offset angles or angular misalignment (pitch, roll and yaw) for both transducer and motion sensor and the latency from the positioning system.

http://www.iho.int/iho_pubs/CB/C‐13/english/C_13_Chapter_3_December2010.pdf(see paragraph 5.2.1.5 Installation and calibration (patch test))

Hydrographic Instrumentation and Calibration

Pitch Test is conducted by running two pairs of reciprocal survey lines at the same speed over a sloping seafloor.

Hydrographic Instrumentation and Calibration ‐ Pitch Test

Hydrographic Instrumentation and Calibration ‐ Pitch Test

Roll Test is conducted by running a pair of reciprocal survey lines, at the same speed, in a regular and flat seafloor.

Hydrographic Instrumentation and Calibration ‐ Roll Test

Hydrographic Instrumentation and Calibration ‐ Roll Test

Yaw Test is conducted by running two adjacent pairs of reciprocal lines, at the same speed, in an area with a well defined bathymetric feature.

Hydrographic Instrumentation and Calibration ‐ Yaw Test

Latency Test is conducted by running two pairs of survey lines at different speeds over a sloping seafloor

Hydrographic Instrumentation and Calibration ‐ Latency Test

Hydrographic Instrumentation and Calibration ‐ Sound Speed Correction

Use velocity meter to measure the actual sound velocity profile for correction

DGPS (e.g. Kau Yi Chau station by Marine Department) Worldwide DGNSS: Correction Service accuracy is the same anywhere in the world. (e.g. C‐Nav)

Satellite Positioning and Navigation

Marine Geodesy

Observed Depth ‐ Tide = Charted Depth 

Chart Datum (CD) of Hong Kong It is approximately the level of Lowest Astronomical Tide (LAT) LAT = lowest tide level to occur under average meteorological 

conditions and under any combination of astronomical conditions. LAT was reduced from tidal observations.   CD of Hong Kong adopted the LAT reduced from the tidal observations 

taken during 1887, 1888, 1889.  Such LAT has been adopted as the zero point for Hong Kong Tide 

Tables since 1917. LAT is adopted as Chart Datum by the International Hydrographic 

Organization (IHO)‐ http://www.iho.int/iho_pubs/misc/M3‐E‐OCT14.pdf (A2.5)

Marine Geodesy

Geodetic Datum Horizontal Datum

WGS 1984 HK80 Geodetic Datum HK80 Grid System

Projection: Transverse Mercator Projection

Marine Geodesy

International Convention for the Safety of Life at Sea (SOLAS) http://www.imo.org/About/Conventions/ListOfConventions/Pages/International‐Convention‐for‐the‐Safety‐of‐Life‐at‐Sea‐%28SOLAS%29,‐1974.aspx

SOLAS regulations related to Hydrographic Survey and Charting:  Regulation 9 : Hydrographic Services Regulation 19 : Carriage requirements for shipborne navigational 

systems and equipment Regulation 27 : Nautical charts and nautical publications Annex 3 : Nautical charts and publications Annex 14 : Electronic charts https://mcanet.mcga.gov.uk/public/c4/solasv/index.html

Marine Charting

Marine Charting

Marine Charting

Paper Nautical Charts http://www.hydro.gov.hk/eng/papercharts.php

Electronic Navigational Charts https://www.hydro.gov.hk/eng/ENCWeb/www/aboutenc.php

Hong Kong Charts

Marine Charting

Specifications of the Charts

Produced in accordance with the specifications ofthe International Hydrographic Organization (IHO)

Positions are referred to the World Geodetic System1984 (WGS84) Datum.

Depths are in metres and are reduced to the ChartDatum, which is approximately the LowestAstronomical Tide.

• Paper Nautical Charts

• Produced in 5 different scales according to their coverage and usage :

1 : 8,000HK0801HK0802HK0803

1 : 15,000HK1501HK1502HK1503HK1504

1 : 25,000HK2501HK2502

1 : 30,000HK3001HK3002

1 : 75,000HK7501

Marine Charting

Marine Charting

Hong Kong Electronic Navigational Charts.

Produced according to the International Hydrographic Organization (IHO) Transfer Standard for Digital Hydrographic Data Specification (S‐57) edition 3.1.

15 Cells covering the whole of Hong Kong waters.

Marine Charting

United Nations Convention on the Law of the Sea (UNCLOS)

http://www.un.org/depts/los/convention_agreements/texts/unclos/unclos_e.pdf

Maritime Boundaries, Local and International Law of Seas

Boundary of the Hong Kong Special Administrative Region http://www.gov.cn/gongbao/shuju/1997/gwyb199723.pdf http://www.legislation.gov.hk/blis_pdf.nsf/6799165D2FEE3FA94825755E0033E532/1EA3

A94829E27D96482575EF0028F9F4/$FILE/CAP_2207_e_b5.pdf

Maritime Boundaries, Local and International Law of Seas

Boundary of the Hong Kong Special Administrative Region

Maritime Boundaries, Local and International Law of Seas

The End