The Sixth International Discussion Group Meeting on Uncertainty Management in Hydrography

1. The Sixth International Discussion Group Meeting on Uncertainty Management in Hydrography May 17, 2007 13:00 - 16:20 US Hydro 2007 Brandon Room Norfolk, VA Sheraton Waterside Hotel Tutorial: Uses of bathymetric data & associated accuracy requirements

2. Meeting agenda Tutorial: Uses of bathymetric data & associated accuracy requirements

3. Related papers at this conference • Ulf Olsson “Practical approach to QC and QA of depth data” (02-03) • Craig Martin “Comparing tide zoning & TCARI for sounding reduction” (08-01) • Crescent Moegling “VDatum for reduction of NOAA bathymetry” (08-02a) • Ian Church “Hydrodynamic model to predict tide witin narrow fjords” (08-03) • Rick Brennan et al “TCARI goes operational” (08-04a) • Rob Hare “Uncertainty management in hydrographic surveys” (10-02) • Brian Calder “Appl. of high-precision timing to distributed survey systems” (10-03) • Doug Lockhart “Analysis of vertical position error est. in TPE & CUBE” (10-04) Tutorial: Uses of bathymetric data & associated accuracy requirements

4. “Do no harm to sonar data” 0.5 cm grid 4 cm Tutorial: Uses of bathymetric data & associated accuracy requirements

5. Here’s the problem Sensor height Depth data Stable Vertical Reference Surface Bathymetry Vertical requirements • Hydrographic sensors not vertically stable • Variations in water surface • Variations in vessel draft • Variations in sensor depth for ROV - AUV - UUV surveys • Uncertainties in defining stable vertical reference surface • Depth directly linked to vertical variations • Depth is a primary hydrographic quantity Tutorial: Uses of bathymetric data & associated accuracy requirements

6. Geoid Slope 20cm/km 0 Tutorial: Uses of bathymetric data & associated accuracy requirements From John Hughes Clarke

7. C-Nav -1Hz Ellipsoid Heights (m) 33 The zigzag ellipsoid height profile is a direct result of 180º survey line azimuth reversals as the vessel climbs up and down the geoid relative to the ellipsoid 27 C-Nav Ellipsoid Heights – 60 sec. average 33 E W E W E W E W E 27 2004 JD278 1800Z 2004 JD279 0000Z 2004 JD279 0600Z 2004 JD279 1200Z Tutorial: Uses of bathymetric data & associated accuracy requirements From John Hughes Clarke

8. http://nauticalcharts.noaa.gov/csdl/vdatum.htm VDatum Transformation Roadmap Similarity Geoid SST Hydrodynamics WGS 84 (G873) MHHW WGS 84 (G730) WGS 84 (orig.) ITRF97 MHW ITRF96 NGVD29 ITRF94 MTL ITRF93 NAD 83 (86) NAVD 88 LMSL ITRF92 ITRF91 DTL ITRF90 ITRF89 MLW ITRF88 Each edge is a transformation SIO/MIT 92 NEOS 90 MLLW PNEOS 90 Tutorial: Uses of bathymetric data & associated accuracy requirements

9. Fremantle DUKCM enhancements • Salinity - lowered UKC threshold by 0.2 m • Developed model for salinity changes in Swan River (container port) • Seasonal variation results in 0.2 m buoyancy (UKC) variations • Squat - lowered UKC threshold by 0.3 m • Vessels squat down by stern, when blocking coefficient is 0.6 • Vessels squat down by bow, when blocking coefficient is 0.8 - 0.9 • Vessels now load to compensate (e.g. heavy to bow for stern squat) • New passage - lowered UKC threshold by 0.2 m • 1997 single-beam survey found new passage over coral reef with 15.4 m minimum depth • Old passage had two high spots @ 15.2 m (environmental sensitivity prevents blasting high spots) • UKC passage re-routed to deeper new route • 2002 new Reson 8125 / PosMV survey of the shipping route Tutorial: Uses of bathymetric data & associated accuracy requirements

10. Meeting agenda Tutorial: Uses of bathymetric data & associated accuracy requirements