BATHYMETRIC SURVEY OF THE ANNAPOLIS BASIN Proposed Fish Pen Installation
Prepared For: Prepared By: Brian Pyke Tiffany Schnare Marine Geomatics W0234124 Centre of Geographic Sciences Centre of Geographic Sciences 50 Elliot Road 50 Elliot Road Lawrencetown, Nova Scotia B0S 1M0 Lawrencetown, Nova Scotia B0S 1M0
Phone:(902) 825-3491 Phone: (902) 247-2013 E-mail: [email protected] E-mail: [email protected]
Document No.: MGEO-021213-01
Revision No.: . Distributed to: Brian Pyke .
Bathymetric Survey Of The Annapolis Basin i
Bathymetric Survey:
Proposed Fish Pen Installation
Author: Tiffany Schnare
Bathymetric Survey Of The Annapolis Basin ii
Revision Logs
Revision Date Description Name Approved By:
0 02-12-2013 Original Circulation Tiffany Schnare
Bathymetric Survey Of The Annapolis Basin iii
Document Control
Copy No. Date Distributed to Location
01 02-12-2013 Brian Pyke Centre of Geographic Sciences
Bathymetric Survey Of The Annapolis Basin iv
Amendments
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Bathymetric Survey Of The Annapolis Basin v
Abstract A bathymetric survey of the Annapolis Basin was performed during the week of September 30th, 2013 by the Marine Geomatics class of 2014 from the Centre of Geographic Sciences (COGS). A single beam echo sounder was used to obtain observed depths for a 150m x 200m study area near Port Wade. The seabed was further examined using a grab sampler and underwater camera built by previous students. Positioning and heading were accomplished with 2 Real-Time Gypsy (RTG) GPS receivers connected to a computer with WinFrog Navigation software. A tide gauge was installed on a pier of the Digby Government Wharf then levelled in using a near-by CHS tidal benchmark. The collected tide corrections along with vessel drafts were applied using Basic Ribbit 2.6 which transformed the depths to be referenced to chart datum. The final product was a CSV file of Northing and Easting points with associated charted depths.
Bathymetric Survey Of The Annapolis Basin vi
Abbreviations
ASCII – American Standard Code for Information Interchange (file format)
CGVD28 – Canadian Geodetic Vertical Datum of 1928
CHS - Canadian Hydrographic Society
CI – Confidence Interval
C-NAV – Civil Navigation (GPS)
COGS – Centre of Geographic Sciences
CRP – Central Reference Point (also known as vehicle reference point)
CSV – Comma-Separated Value (file format)
CTD – Conductivity, Temperature, Depth
DEM – Digital Elevation Model
GIS - Geographic Information Systems
ITRF05 – International Terrestrial Reference Frame, Epoch 2005
LLWLT – Lowest Low Water Large Tide
MGEO – Marine Geomatics Program
RTG - Real-Time Gypsy
SOS – Speed of Sound
TBM – Temporary Benchmark
WGS84 – World Geodetic System of 1984
Bathymetric Survey Of The Annapolis Basin vii
References Canada, G. o. (n.d.). CHS Benchmarks in Digby. Retrieved November 23, 2013, from Integrated Science Data Management (ISDM): http://www.meds-sdmm.dfo- mpo.gc.ca/meds/Prog_Nat/benchmark/single_station2_e.asp?T1=325
Canada, G. o. (n.d.). Digby Tide Tables. Retrieved September 23, 2013, from Fisheries and Oceans Canada: http://www.waterlevels.gc.ca/eng/station?type=0&date=2013%2F09%2F30&sid=325&tz =ADT&pres=1
Coverage Maps. (n.d.). Retrieved November 26, 2013, from C-NAV GNSS: http://www.cnavgnss.com/maps
Bathymetric Survey Of The Annapolis Basin viii
Table of Contents 1. Introduction ...... 1 Overview ...... 1 Study Area ...... 1 Location Information ...... 1 2. Summary of Results ...... 2 Data ...... 2 Initial Assessment ...... 2 3. Survey Parameters ...... 3 Geodetics ...... 3 Horizontal ...... 3 Vertical ...... 3 Control ...... 3 Vertical ...... 3 Horizontal ...... 4 4. Organization ...... 5 Personnel ...... 5 Equipment ...... 6 Planning & Reconnaissance ...... 6 Calibrations ...... 7 In-Office ...... 7 On-Site ...... 7 4. Survey Operations ...... 8 Mobilization ...... 8 Offsets ...... 8 Data Acquisition ...... 8 October 3rd ...... 8 October 4th ...... 8 Management ...... 9 Processing ...... 9 Presentation ...... 10 5. Accuracy ...... 11 IHO Standards ...... 11 Bathymetric Survey Of The Annapolis Basin ix
Horizontal Accuracy ...... 11 Vertical Accuracy (reduced depths) ...... 11 Water Level Errors ...... 11 Tide Gauge ...... 11 Offset to work area ...... 12 Levelling & Installation of Tide Gauge ...... 12 Timing ...... 13 Sear Surface ...... 13 RSS – Water Level ...... 13 Observed Depth Errors ...... 13 VBES ...... 13 Settlement & Squat ...... 13 Sea Floor ...... 14 Heave, Pitch, & Roll ...... 14 Speed of Sound (SOS) ...... 14 RSS – Observed Depth Errors ...... 14 Horizontal Positioning Errors ...... 15 6. Comparison Charts ...... 16 7. Coverage ...... 16 8. Conclusion & Recommendations ...... 17 9. Safety ...... 18
Bathymetric Survey Of The Annapolis Basin x
List of Figures Figure 1 Keymap of Digby, Nova Scotia and surrounding areas...... 1 Figure 2 DEM of the study area in profile view showing a dip in the seafloor...... 3 Figure 3 Map of the Digby wharf showing tide gauge and CHS benchmark placement...... 3 Figure 4 Predicted tide table for 13/09/30 ...... 7 Figure 5 Comparison of Tides at Digby and Parkers Cove for October 3rd ...... 12 Figure 6 Depth versus Speed of Sound ...... 14
List of Tables Data folders and structure ...... 2 Near-by C-NAV reference and uplink locations ...... 4 Personnel ...... 5 Equipment ...... 6 WinFrog Folder structure ...... 9
Table of Appendices Appendix A Chart Appendix B System Diagram Appendix C Offsets & Measurements Appendix D Levelling Field Notes Appendix E C-NAV Coverage Map Appendix F Survey Line Logs Appendix G Daily Weather Conditions Appendix H Daily Logs
Bathymetric Survey Of The Annapolis Basin 1
1. Introduction
Overview The whole project was completed over the course of five days from September 30th to October 4th with the survey occurring October 2nd and 3rd. Two RTG GPS receivers were used in team with WinFrog for positioning, depths were recorded with a single-beam echo sounder transducer. Basic Ribbit 2.6 handled the post-processing while the final plot was created with AutoCAD.
This survey was vital to chart the shoalest depths in a study area to assess if it could be used as a location for future fish pens.
Study Area The study area covered a 30000m2 (150m x 200m) area in the Annapolis Basin near Port Wade.
Study area corners:
North-West: Bay of Fundy 44° 40’ 29.265”N
65° 42’ 08.746”W
Annapolis North-East: Royal Port 44° 40’ 26.872”N
Wade 65° 42’ 05.847”W
South-West: 44° 40’ 20.459”N Cornwallis 65° 42’ 10.319”W Digby
South-East:
44° 40’ 22.333”N
65° 42’ 03.364”W NORTH
Figure 1 Keymap of Digby, Nova Scotia and surrounding areas. Centre of the surveyed area as determined from the final plot: 44° 40’ 24.614”N 65° 42’ 06.648”W Location Information The Bay of Fundy is famous for having the highest tides in the world, in a 13 hour cycle they can fluctuate up to 14m. The waters are full of marine life from dolphins and whales to haddock and the famous Digby scallops, making fishing the biggest economic and employment sector for the villages situated on the shores. The town of Digby is one such fishing village; located on the shore of the Annapolis Basin, connected to the Bay of Fundy by the Digby Gut. Bathymetric Survey Of The Annapolis Basin 2
2. Summary of Results
Data The data can be found on the MGEO drive on the COGS server. (P:\MGEO2014\Tiffany\Digby\)
The folders are structured as follows.
Folder Name Sub-Folder Name Description of Files
Raw Data
CTD data The uneditied data recorded by the CTD.
Tide Gauge The uneditied data recorded by the Tide Gauge. The raw files that were created in WinFrog while on WinFrog the vessel performing the survey. Processed Data The final shapefile and DEM created with the Ribbit GISOutputs Outputs. The final .csv files with Northing/Easting points and RibbitOutputs associated depth. The Tide Gauge data in excel/csv format edited to be TideFiles referenced to chart datum and predicted tides for the period of the survey. Reports
Notes Scans and transcribed notes from field books. Instructions on how to process the raw data in Basic RibbitManual Ribbit 2.6. SurveyReport The final report for the survey.
Initial Assessment The average charted depth in the area is 9.487m based on the positive 4m overplot removal from Basic Ribbit. The area is relatively flat apart from one potential error or anomaly at 4950108mN, 285761.2mE where a dip in the seafloor is recorded at approximately 11.200m. No further abnormalities were recorded.
Figure 2 DEM of the study area in profile view showing a dip in the seafloor. Bathymetric Survey Of The Annapolis Basin 3
3. Survey Parameters
Geodetics All measurements are expressed in metres and forms thereof.
Horizontal Datum: ITRF05
Ellipsoid: WGS84
Semi-major axis (a): 6378137.0 m
Inverse flattening (1/f): 298.257223563
Projection: UTM Zone 20 North
Central meridian: 63° W
False Northing: 0 m
False Easting: 500000 m
Scale Factor at central meridian: 0.9996
Latitude at origin: 0 °
Vertical Tidal benchmarks referenced to: CGVD28 (LLWLT ~ Chart Datum)
Control
Vertical Once the tide gage was installed on a pier of the Digby Government Wharf the top of the pole was used as a temporary benchmark (TBM1) and levelled in using official CHS vertical benchmark 87N9151. The value obtain (0.597m) was used along with the published elevation (10.221m) and the measurement from the tide gauge to the top of TMB1 Tide (10.315) to determine the height of the tide gauge above Gauge chart datum (0.502m). This offset was applied to all observed depths from the sounder as one of the steps to transform depths relative to chart datum.
Field notes from this job can be found in appendix D.
Figure 3 Map of the Digby wharf showing tide gauge and CHS benchmark placement.
Bathymetric Survey Of The Annapolis Basin 4
Horizontal The C-NAV 2050M systems are quoted by C&C Technologies to have a horizontal accuracy of approximately +0.245m at 2σ. The corrections that the satellites are sending to the receivers come from near-by reference sites which monitor the satellites, atmospheric conditions and other such variables; then communicates with uplink sites to upload the proper corrections to the satellites for broadcasting.
The following is a list of the closest reference and uplink sites to the study area.
Station Type Location Kellyville, Greenland (Station #60) Reference Farmington, Connecticut, USA (Station #151) Laurentides, Canada Uplink Southbury, Connecticut, USA
See appendix E for an official coverage map from C&C Technologies.
Bathymetric Survey Of The Annapolis Basin 5
4. Organization
Personnel Below is a list of the personnel that was on the vessel each day of the survey. The crew was divided into two groups for days three and four, half of the people were on the boat surveying the seabed while the others were on land levelling then the next day it was switched so everyone had a chance to be a part of each aspect of the survey.
Sept. 30th, Oct. 1st, 4th. Oct. 2nd Oct. 3rd Alicia McLaughlin Alicia McLaughlin Archan Dawadi Archan Dawadi Gillian Spears Camille Brown Camille Brown Jeremy Thompson Courtney Dow Courtney Dow Jonathan Downing Jillian Parsons Gillian Spears Jonathan Underwood Joel Onwodi Jeremy Thompson Liz Van Nuland Luke Melanson Jillian Parsons Megan McDonald Renee Robertson Joel Onwodi Roman Husiuk Tiffany Schnare Jonathan Downing Victoria Ehman Brian Pyke* Jonathan Underwood Brian Pyke* Troy Greene* ** Liz Van Nuland Troy Greene* Greg Tagert ** Luke Melanson Greg Tagert Megan McDonald Renee Robertson Roman Husiuk Tiffany Schnare Victoria Ehman Brian Pyke* Troy Greene* ** Greg Tagert ** *Supervisor Captain
Bathymetric Survey Of The Annapolis Basin 6
Equipment The following is an outline of all the major equipment used.
Name Maker Model No. Complete with:
Passage Provider Dean Kenley N/A All necessary gear. (Vessel) (Owner) Tide Gauge RBR 420 TG
Automatic Level Pentax AL8-22 Tripod, turning point and rod.
Grab Sampler COGS N/A
Desktop Computer (x3)1 Dell N/A Keyboards, mice, power cables, etc.
Underwater Camera COGS N/A Television and connector cables Single Beam Echo Knudson BP320 Transducer and 24 VDC power supply Sounder2 CTD RBR XR 620 C&C 2 Receivers, 2 Antennas, serial and C-NAV RTG System3 2050M Technologies power cables. Generator (3kva) & DC N/A N/A Power Supply Various Tools and Multimeter, gender changers, and N/A N/A Connectors measuring tape.
1Each major aspect of the survey had its own computer;
1. WinFrog/Navigation, 2. Echo Sounder, 3. C-NAV.
This way no one computer was relied on for more then a small portion of the survey so that if it were to fail there was always an alternative.
2The Echo Sounder featured a 9 ° beam width.
3Both heading and position were handled by the C-NAV system.
Planning & Reconnaissance The study area and surrounding location was explored using CHS chart 4396 prior to arriving at the site, this gave us a sense for the depths to expect in the region.
The dates were selected based on weather conditions and available times of everyone involved. Once the dates were confirmed the vessel and equipment was reserved by Supervisor Pyke. Bathymetric Survey Of The Annapolis Basin 7
The predicted tides tables from the Government of Canada – Fisheries and Oceans Canada website were consulted to decide on the best time to install the tide gauge. It turned out to be Monday September 30th at 14:55. This was the time of lowest tide therefore it could be placed at a depth that would ensure the waterline never fell below the tide gauge.
Calibrations
In-Office The following actions were taken while in the office to Figure 4 Predicted tide table for ensure as little time as possible was spent troubleshooting while 13/09/30 performing the survey.
All of the equipment was calibrated, tested and set-up before being considered useable for the survey. The C-NAV system was tested by setting up both receivers outside near the building so that its cords extended through a window and plugged into the computer. One of the receivers was working properly but the second receiver was malfunctioning and displaying values there were noticeable off by a couple hundred metres. It was re-set-up and tested but the problem was reoccurring. As the C-NAV was the best positioning system at our disposal it was re-tested until the day of the survey when it was decided that it would still be brought with. Once set-up on the vessel it worked perfectly and with no glitches.
To test the transducer it was securely hung from a high ceiling and placed in a medium sized bucket of water. It was then completely set-up turned on and inspected. Everything was noted to be working properly.
Once the testing was finished all of the equipment was stored in a way that would ensure everything made it to the location in one piece and anything essential to a particular instrument was stored together for ease of access.
On-Site Additional measures were taken the day of the survey to guarantee high quality data.
The speed of sound through water was measured using two methods and finalized to be 1495.490 m/s by. First a bar check was performed to set the SOS for the sounder then a CTD was used to adjust the values to allow the reverberations to best move through the water column.
Before the levelling equipment was used for any official jobs a 2-peg test was performed to ensure the validity of the values obtained. The result of the test showed the instruments had an approximate error of 0.000m.
Bathymetric Survey Of The Annapolis Basin 8
4. Survey Operations
Mobilization The vessel was outfitted with all instruments and computers on September 30th.
A pre-built two-level stand specially constructed for use with the computer system was set-up in the cabin on the port side. The computers were situated on the middle shelve then the C-NAV and Sounder monitors were placed on the top, the WinFrog Monitor was placed on the built-in worktop. All computers and accompaniments were tightly secured in place using ropes.
The echo sounder was fixed to a 2x4 board with worm clamps. Then securely suspended over the port side and stabilized using more clamps to fasten to the railing and using a smaller board as a spacer.
The primary GPS receiver was attached to the top of the board holding the sounder. The secondary GPS receiver was set-up on a 2m pole near the stern on the starboard side.
Offsets The small board used to stabilize the echo sounder was used as the CRP to measure all devices. Then 0.2m was added to the X axis values to reference them to the echo sounder. The vessel measurements and device offsets can be found in appendix C.
The day of mobilization the sounder was measured to be 1.03m from the waterline. Each day thereafter it was re-measured and updated in the system to obtain proper readings. The first day surveying it was measured to be 1.03m, the next day after taking on fuel it was 1.05m. When measuring the offset a carpenter’s level was used to determine when the boat was level and the measurements were only taken at that instance.
Data Acquisition
October 3rd The vessel left from Digby Yacht Club wharf and headed towards the study area approximately 3000m North-East where fifteen 200m parallel main lines along with five 150m tie lines had already been determined.
The azimuths of the main survey lines were:
Forward 320° & Reverse 140°
While acquiring the data all crew members completed each task for the entirety of at least two survey lines. This ranged from maneuvering the vessel, monitoring the echo sounder, logging the related information for each survey line, and operating WinFrog to make certain the vessel stayed on track while also ensuring each survey line was being properly recorded.
October 4th The final day of the survey a grab sampler was deployed off the shore of Smiths Cove. It picked up a small portion of the seabed which was briefly analyzed by onboard geologists. From Bathymetric Survey Of The Annapolis Basin 9
the sample they made an educated guess that the floor of the Digby Basin consisted of silty clay and very little sand.
An underwater camera hooked up to a television screen was set out near Bear Island. The view showed murky waters with floating seaweed, many scallops and assorted shells.
Management To neatly organize the raw data files over the course of the project completely new folders were created on all computers for both days of the survey and on the WinFrog computer multiple sub-folders were created for each data type that would be collected. At the end of each day one team was tasked with copying all of the data from the computers to an external drive for safe keeping.
Below is the structure of the folders set for the output data from WinFrog; they along with the accompanying data can be found at the following path: ‘P:\MGEO2014\Tiffany\Digby\RawData\WinFrog’.
Sub-Folder/Data File Description File Extension File Name Stores all of the set parameters and settings for the Config project. This was saved multiple times in case of any .cfg sudden failures. Logs Records of everything performed in WinFrog. .LOG Misc For any unexpected files. N/A Pictures Area features. .PIC All information relating to the vessel and actual Ppg2 .RAW surveyed lines. SurveyLines The pre- set survey lines. .PTS Vehicles The outline and offsets of the vessel. .veh Waypoints Point features. .WPT Xponders N/A N/A Log of all operations that the user(s) performed in 276-Audit.txt .txt WinFrog. Contains portions of the main data; depths, position, EVENT-g2.DAT .DAT etc.
Processing The post-processing of the data was performed using Fugro Pelagos Basic Ribbit 2.6 software.
Vessel draft and tide corrections were added to the observed depths from the echo sounder to produce depths referenced to chart datum. They were then merged with the point file from the primary GPS receiver to create a xyz grid of coordinates with related depths.
Four overplot removals were generated from the xyz grid to extract the shoalest depths within a circle radius of 4m and 8m respectively. This thinned out the points to display only Bathymetric Survey Of The Annapolis Basin 10
necessary data and made the final plot easier to understand. The first two outputs were created using data with negative depths, the second two used positive depths. Each result was exported as a ASCII file and converted to CSV.
A detailed instruction booklet for the processes above can be found in the ‘Reports’ > ‘RibbitManual’ folder.
Presentation A contour plot of the surveyed area is currently being prepared with AutoCAD software and will be inserted in Appendix A when complete.
The CSV created with positive depths and a 4m circle radius was used to produce the chart. The positive depth option was chosen because the outputs using negative depths were isolating values that were the deepest depths as opposed to the desired shallowest depths. In addition the 4m output was selected because it produced approximately 60% more data then the 8m outputs.
Bathymetric Survey Of The Annapolis Basin 11
5. Accuracy
Unless otherwise indicated all final results are stated at 2σ (95% CI).
IHO Standards According to the IHO specification tables found on the MGEO network the following equations are what the IHO see as minimum requirements to meet second order surveying.
Horizontal Accuracy
Hz = 20m + 5% of (minimum) depth
Hz = 20m + 0.355m
Hz = 20.355m
End result; obtained positions must be within 20.355m of their true location.
Vertical Accuracy (reduced depths) 2 2 Vz = √[a + (b*d) ] Where: a = 1 b = 0.023 d = depth (minimum) 2 2 Vz = √[1 + (0.023*7.1m) ]
Vz =1.026m
End result; reduced depths must be within 1.026m of their true elevation.
Water Level Errors Water levels and related variables can possibly cause a large error in observed depths; the following is the equations to calculate the total error.
2 2 2 2 2 σWL= √( σSG + σoff + σL + σt + σss )
Where:
σSG = Tide gauge
σoff = Offset to work area
σL = Levelling and installation of tide gauge
σt = Timing
σss = Sea Surface
Tide Gauge The tide gauge uses a piezo-resistive strain gauge sensor. Full scale (limit of water above sensor) for this particular model is 60m (30psi), resolution is <0.001% full scale and the accuracy is 0.05% full scale.
The accuracy at the sensor is:
σSG = 0.0005 * 60m = 0.073m Bathymetric Survey Of The Annapolis Basin 12
Offset to work area The study area was approximately 3000m (3km) from the Digby Government Wharf. As such the tides would’ve been higher at the tide gauge then at the same moment at the surveyed site.
Tide difference is estimated to be low because the survey was completed during high tide therefore little change in the water levels.
Water levels and related times were researched for both Digby and Parkers Cove then a pessimistic estimation for the maximum range/phase was estimated to be 0.020m in 1 minute.
σoff = 0.049m
Figure 5 Comparison of Tides at Digby and Parkers Cove for October 3rd.
Levelling & Installation of Tide Gauge There are three variables associated to levelling that were taken into consideration for the final error value by using the following equation;
2 2 2 σL = √( σBM + σL + σM )
Where:
σBM = Benchmark shifting slightly since the last time it had been surveyed.
σL = Levelling to TBM1.
σM = Measuring from 2 2 2 σL = √( 0.004m + 0.001m + 0.010m )
σL = 0.009m Bathymetric Survey Of The Annapolis Basin 13
Timing The clocks were set using a watch and so we estimated the timing error to be 30 seconds and the effect of the error would increase with time.
σt = 0.005m per minute
Sear Surface The software is good at removing much of the error associated with waves but there will still be a little bit that needs to be taken into account. The pessimistic estimation is:
σss = 0.003m
RSS – Water Level 2 2 2 2 2 σWL= √( 0.073m + 0.049m + 0.009m + 0.012m + 0.007m )
σWL= 0.089m
The total error associated with water levels is 0.089m.
Observed Depth Errors The error that could possibly be found in the observed depths can be estimated with the following equation:
2 2 2 2 2 σD= √( σRmeas + σdB + σss + σdH + σdC )
Where:
σRmeas = VBES
σdB= Seafloor
σss = Settlement and Squat
σdH = Heave, Pitch, and Roll
σdC = Speed of Sound (SOS)
VBES The echo sounder itself will be responsible for some error.
2 2 σRmeas = √(Δrs/2) + (C* τ/4)
Where: Δrs = range sampling resolution
τ = Pluse Length
C = Speed of Sound
2 2 σRmeas = √(0.010/2) + (1495.490 * 0.0001/4)
σRmeas = 0.038m
Settlement & Squat After taking on fuel the vessel settled 2cm and squat is estimated to be 0.010m.
2 2 σss = √(0.020m + 0.010m )
σss = 0.022m Bathymetric Survey Of The Annapolis Basin 14
Sea Floor The sea floor is not flat thus introduces some error into the readings.
2 2 σ dB = {d[1-cos(ψx/2)]}
Where: d = depth (minimum or maximum)
ψ = beam width By using the maximum depth of the area the largest error can be found, the minimum depth is used to find the least possible error. Max: 0.037m Min: 0.023m
Heave, Pitch, & Roll No sensor was used to measure the heave, pitch, and roll of the vessel therefore the following values are best guess estimation. The maximum amount the vessel was heaving was estimated to be +0.010m. The errors for pitch and roll will be minimal because the survey was completed on a calm day and the vessel was not rolling or pitching anywhere near 4.5°.
Combining the errors the final value for heave, pitch, and roll is: σdH = 0.150m
Speed of Sound (SOS) The following equation calculates the errors related to SOS.
σdC = r*ΔC C Where:
r = range (max depth) C = speed of sound σdC = 12*2 . 1495.490 σ = 0.016m dC Figure 6 Depth versus Speed of Sound
RSS – Observed Depth Errors 2 2 2 2 2 σD= √( 0.038m + 0.037m + 0.020m + 0.100 + 0.016m )
σD= 0.116m The total error associated with the observed depths is 0.116m.
Bathymetric Survey Of The Annapolis Basin 15
Horizontal Positioning Errors The complete equation to calculate the horizontal position errors is as follows:
2 2 2 2 2 σHoriz = √(σpos + σh/p/r + σoff + σt + σSFP )
Where:
σpos = Variance of Position
σh/p/r = Heave, Pitch, Roll
σoff = Offsets
σt = Timing
σSFP = System’s Horizontal Accuracies
2 2 2 2 2 σHoriz = √(0.050m + 0.034m + 0.025 + 0.005 + 0.100m )
σHoriz = 0.119m
Bathymetric Survey Of The Annapolis Basin 16
6. Comparison Charts
Figure 7 Depth versus Salinity
Figure 8 Depth versus Pressure
7. Coverage Approximately 15% of the seafloor was covered using a 9° beam width, 10m line spacing, assuming straight lines, and not including tie lines.
Tan 4.5° * 10m 0.787 * 2 1.576/10 15% Bathymetric Survey Of The Annapolis Basin 17
8. Conclusion & Recommendations The survey was a success, high quality data was obtained and much was learned as a result of this project. For future reference the following is an overview of anything that could be done differently upon during the next survey.
Do not delete WinFrog user file(.wini); this is an automatically created file that was accidentally deleted which caused a slight delay as it also deleted the key that allows WinFrog to be used fully and not as a simple demo mode.
During the survey many members got sidetracked by their tasks and forgot to write logs in their field books. It would be a good idea to record better logs of time, locations and what is happening at every moment.
Always have a back-up computer; for this survey their were a total of three computers meaning when the computer dealing with the C-NAV system failed it was possible to connect the C-NAV to the echo sounder computer and it worked fine from then on.
Finally, always double check the geodetics. It was thought that the geodetics had been set to add a projection but later-on when in the office it was noticed that they geodetics did not hold therefore they reverted back to WGS84.
Bathymetric Survey Of The Annapolis Basin 18
9. Safety To ensure the safety of all personnel involved in the survey several safety measures were taken. Life vests were wore by all when on the vessel along with proper footwear and attire. The first morning of the survey everyone was briefed by the captain on what to do if any major issues were to occur while on the vessel. While equipment and tools were not being used they were stored in the lower cabin to keep the vessel clear of as many hazards as possible. As a result of the safety precautions no one was harmed during the survey.
Appendix A
Map to be placed here.
System Diagram
Offsets & Measurements
Levelling Field Notes
Survey Line Logs
Times are in UTC
Line Forward/Reverse Time File Name M F 16:48 276-1648.raw Ma R 16:50 276-1650.raw M + 10 F 16:53 276-1653.raw M + 20 R 16:56 276-1656.raw M + 20a F 16:59 276-1659.raw M + 30 R 17:02 276-1702.raw M + 100 F 17:08 276-1708.raw M + 40 R 17:11 276-1711.raw M + 90 F 17:15 276-1715.raw M + 60 R 17:17 276-1717.raw M + 50 F 17:21 276-1721.raw M + 40a R 17:23 276-1723.raw M + 80 F 17:26 276-1726.raw M + 70 R 17:32 276-1732.raw M + 100a F 17:35 276-1735.raw M + 110 R 17:38 276-1738.raw M + 120 F 17:43 276-1743.raw M + 100b R 17:46 276-1746.raw M + 100c F 17:49 276-1749.raw M + 150a R 17:52 276-1752.raw M + 150b F 17:54 276-1754.raw M + 140a R 17:57 276-1757.raw M + 140b F 17:59 276-1759.raw M + 130a R 18:06 276-1806.raw M + 130b F 18:09 276-1809.raw T + 150 R 18:15 276-1815.raw T + 100 F 18:17 276-1817.raw T + 50 R 18:22 276-1822.raw
Daily Weather Conditions.
Date September 30 October 1 October 2 October 3 October 4 Overview Sunny Overcast/Raining Sunny Sunny Sunny Temperature 8.4 °C 12.5 °C 15.1 °C 14.0 °C 13.6 ° Pressure 102.0 kPa 101.2 kPa 101.1 kPa 101.7 kPa 101.9 kPa Humidity 97% 94% 82% 78% 79% Wind NE 1 km/h N 33 km/h SSE 4 km/h WSW 25 km/h W 18 km/h
Daily Logs All times are quoted in UTC
*Times are approximate September 30th, 2013 Time Task 14:20 Arrived on-site 16:30 Mobilized the vessel - Start 20:30 Mobilized the vessel - End
October 1st, 2013 Time Task 14:30 Arrived on-site 15:30 Measured offsets 16:15 Configured WinFrog 17:55 Installed Tide Gauge
October 2nd, 2013 Time Task 14:20 Arrived on-site 16:30 Levelling-Start 18:00 Levelling-End
October 3rd, 2013 Time Task 14:30 Arrived on-site 15:30 Left Wharf 16:48 Survey-Start 18:22 Survey-End 19:45 Arrived at Wharf
October 4th, 2013 Time Task 14:15 Arrived on-site 14:45 Left Wharf 15:23 Grab Sampler Deployed 15:55 Camera Deployed 16:15 Arrived at Wharf 17:00 De-mobilized the vessel