HYDROGRAPHIC SURVEYS SPECIFICATIONS AND DELIVERABLES March 2019 U.S. Department of Commerce National Oceanic and Atmospheric Administration National Ocean Service Contents 1 Introduction ......................................................................................................................................1 1.1 Change Management ............................................................................................................................................. 2 1.2 Changes from April 2018 ...................................................................................................................................... 2 1.3 Definitions ............................................................................................................................................................... 4 1.3.1 Hydrographer ................................................................................................................................................. 4 1.3.2 Navigable Area Survey .................................................................................................................................. 4 1.4 Pre-Survey Assessment ......................................................................................................................................... 5 1.5 Environmental Compliance .................................................................................................................................. 5 1.6 Dangers to Navigation ........................................................................................................................................... 6 1.6.1 Definition ......................................................................................................................................................... 6 1.6.2 DTON Submission to Non-NOAA Source Authorities ............................................................................. 7 1.6.2.1 Federal USACE Channels .........................................................................................................................7 1.6.2.2 Aids to Navigation (USGC).......................................................................................................................7 1.6.2.3 Bridge Heights.............................................................................................................................................8 1.6.2.4 Pipelines.......................................................................................................................................................8 1.6.3 DTON Submission to NOAA ........................................................................................................................ 8 1.6.4 Charted Feature Remove Request (Anti-DTON) ....................................................................................... 9 1.7 Seep and Pipeline Report........................................................................................................................................9 2 Datums ............................................................................................................................................10 2.1 Time ....................................................................................................................................................................... 10 2.2 Horizontal Datum ................................................................................................................................................ 10 2.3 Vertical Datum ...................................................................................................................................................... 10 2.3.1 Charted Soundings and Heights ................................................................................................................. 10 2.3.2 Survey Platform Positioning (Control) ...................................................................................................... 10 3 Hydrographic Positioning .............................................................................................................11 3.1 GNSS Terminology .............................................................................................................................................. 11 3.2 Horizontal Control ............................................................................................................................................... 11 3.3 Vertical Control .................................................................................................................................................... 12 3.4 Differential GNSS Reference Stations (DGPS & ERS) .................................................................................... 12 3.5 Ellipsoid Referenced Survey Control ................................................................................................................. 12 3.5.1 ERS Planning and Operational Requirement .......................................................................................... 13 3.5.2 ERS GNSS Infrastructure ........................................................................................................................... 13 3.6 ERS Datum Transformation Requirements ...................................................................................................... 14 3.6.1 VDatum ........................................................................................................................................................ 14 3.6.2 Ellipsoidally-Referenced Zoned Tides (ERZT) ...................................................................................... 15 3.6.3 Constant Value Separation Model ............................................................................................................. 15 4 Tides and Water Levels Requirements .........................................................................................16 4.1 General Project Requirements and Scope ......................................................................................................... 17 4.1.1 Scope ............................................................................................................................................................. 17 4.1.2 Objectives ..................................................................................................................................................... 17 4.1.3 Planning and Preliminary Tidal Zoning .................................................................................................. 17 4.1.4 NOS Control Stations and Data Quality Monitoring ............................................................................. 18 4.1.5 General Data and Reference Datum Requirements ................................................................................ 18 4.1.6 Error Budget Considerations ..................................................................................................................... 19 4.2 Data Collection and Field Work ......................................................................................................................... 21 4.2.1 Water Level Station Requirements ............................................................................................................ 21 4.2.2 Water Level Sensors ..................................................................................................................................... 22 4.2.2.1 Bottom Mounted Pressure Gauge (BMPG) ...................................................................................... 25 4.2.2.2 GPS Tide Buoys ..................................................................................................................................... 26 4.2.3 Station Installation, Operation and Removal .......................................................................................... 27 4.2.4 Tide Staff ...................................................................................................................................................... 28 4.2.5 Bench Marks ................................................................................................................................................. 30 4.2.5.1 Types of Bench Marks ........................................................................................................................... 31 4.2.5.2 Digital Photographs of the Station and Bench Marks ....................................................................... 32 4.2.5.3 Obtaining and Recording of Positions of Stations, Data Collection Platform, Sensors, and Bench Marks Using a Handheld GPS Receiver .......................................................................................................... 32 4.2.6 Leveling ........................................................................................................................................................... 33 4.2.6.1 Leveling Frequency ................................................................................................................................ 33 4.2.6.2 Stability ................................................................................................................................................... 33 4.2.7 Water Level Station Documentation ......................................................................................................... 34 4.2.8 Additional Field Requirements .................................................................................................................