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TEC-GIS45-07 · Lesson 12 · 12 clock hours · practice

Hydrographic Field Report: Documentation, Metadata, and Presentation

Objective. Students compile a complete hydrographic field report following the NOAA Hydrographic Survey Specifications and Deliverables outline, including metadata, data-quality statement, tidal correction summary, and corrected sounding deliverable, and present findings orally.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by an industry-certified professional or by a certification or approval body. It is a study draft and may contain errors. Do not use it as instructions for work on a job site or on live equipment. Always follow your instructor, your supervising professional, and current official references and regulations.

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Hydrographic Field Report: Documentation, Metadata, and Presentation

A hydrographic survey is not finished when the last sounding is collected. The deliverable that employers, agencies, and clients actually receive is a complete field report—a documented record showing what was measured, how it was measured, how data were processed, and whether the results meet an accepted quality standard. NOAA's Hydrographic Survey Specifications and Deliverables (HSD) defines the structure and content that federal and commercial hydrographic reports are expected to follow. Learning to build a compliant report is as important as learning to operate the echosounder.

Required Report Sections

A report organized to the NOAA HSD outline typically contains the following major sections:

1. Project Overview — survey area description, chart datum used (usually Mean Lower Low Water, MLLW, for US coastal work), purpose of the survey, and dates of field operations.

2. Vessel and Equipment Records — the survey vessel name, hull type, sonar make and model, transducer frequency, GPS or GNSS receiver specifications, and any calibration certificates for the sound velocity profiler (SVP).

3. Processing Log — a chronological account of every processing step applied to the raw data: sound velocity corrections, draft and squat corrections, motion compensator application, tide correction, and any manual editing.

4. Tidal Correction Summary — the tide gauge station(s) used, the method (direct gauge, zoned tides, or RTK ellipsoid-to-datum separation), and a table showing the range of tidal offsets applied over the survey period.

5. Data-Quality Assessment — cross-line comparison statistics and coverage analysis (detailed below).

6. Corrected Sounding Deliverable — the final cleaned point file or surface, referenced to chart datum, in the specified format (often CARIS or BAG for federal work; in this program, an ArcGIS Pro–exported product is acceptable).

7. Appendices — raw data files, original tide records, SVP casts, and the field logbook.

Metadata

Metadata is structured information about your data. Every geospatial deliverable must carry metadata so a future user knows what coordinate reference system was used, when data were collected, what instrument accuracy class applies, and who is responsible for the product. For this program the minimum metadata fields are: survey date range, horizontal datum (typically NAD 83), vertical datum, EPSG codes for the projected coordinate system, instrument make/model, horizontal and vertical accuracy estimates, and the name of the processing technician. ArcGIS Pro can generate ISO 19115-compliant metadata directly from the layer properties panel.

Data-Quality Statement and IHO Order 1

The data-quality section is the technical core of the report. You must populate it with actual values from your project, not placeholders.

The International Hydrographic Organization (IHO) Standards for Hydrographic Surveys (S-44) defines several survey orders. IHO Order 1a/1b is the standard most commonly required for harbor and coastal navigation surveying. Key thresholds under Order 1 include:

Your data-quality form must state the cross-line mean difference, the standard deviation of differences, total soundings collected, soundings rejected (and reason), percentage of the survey polygon covered, and a final compliance statement: This survey meets / does not meet IHO Order 1 at the 95% confidence level.

Tidal Correction Summary

Correct documentation of tidal corrections protects the legal validity of the depth record. State which tide gauge was used, its distance from the survey area, the predicted versus observed water levels, and the maximum tidal range encountered. If RTK-derived water-level reduction was used instead of a tide gauge, note the base station, the ellipsoid separation model (GEOID model version), and the resulting datum offset.

Oral Presentation Standards

You will present your survey findings in a 10-minute briefing. Professional oral presentations in surveying and GIS follow a clear structure: (1) introduce the survey area and purpose; (2) describe methodology and equipment; (3) present the data-quality results using a map and statistics table; (4) deliver one concrete recommendation for improving coverage or accuracy in a follow-up survey. Speak to your audience, not to your slides. Be prepared to explain why a sounding was rejected or how the tidal correction was applied—these are typical quality-assurance questions.

Safety Note

All field documentation must include a note on the personal protective equipment (PPE) worn during waterborne operations: personal flotation devices (PFDs), appropriate footwear, and emergency communication equipment. If the survey involved small-vessel operations, the vessel safety checklist and float plan should appear in the appendices. This documentation protects the crew and demonstrates regulatory compliance to the client.

Key terms9

NOAA Hydrographic Survey Specifications and Deliverables (HSD)NOAA's official document defining the required content, format, and quality standards for hydrographic survey reports submitted to or following federal practice.
IHO S-44The International Hydrographic Organization publication that defines survey order classifications and their associated accuracy and coverage requirements for hydrographic surveys worldwide.
IHO Order 1A survey accuracy classification in IHO S-44 appropriate for harbor and coastal navigation areas; it specifies Total Vertical Uncertainty limits and requires full seafloor coverage.
Total Vertical Uncertainty (TVU)The combined vertical error estimate for a depth measurement at the 95% confidence level, accounting for fixed instrument errors and depth-dependent errors.
Cross-line checkA quality-control method in which check lines are run perpendicular to main survey lines; differences in depth at crossing points are used to estimate the survey's vertical precision.
MetadataStructured descriptive information about a dataset, including coordinate reference system, collection date, instrument specifications, accuracy estimates, and responsible party.
Tidal correction summaryThe section of a hydrographic report documenting which tide gauge or RTK method was used to reduce sounding depths to chart datum, including the temporal range and magnitude of corrections applied.
Chart datumThe vertical reference surface to which charted depths are reduced; Mean Lower Low Water (MLLW) is the standard chart datum used on US nautical charts.
Sound Velocity Profile (SVP)A measurement of how sound speed changes with water depth due to temperature, salinity, and pressure; used to correct the path of acoustic signals from the echosounder.

Worked examples4

1. Calculate whether a cross-line mean difference meets IHO Order 1. You collected 45 crossing-point comparisons. The sum of all absolute differences is 11.25 m. The standard deviation of differences is 0.18 m. State the mean difference and evaluate compliance if the allowable limit at the survey's average depth (10 m) is 0.50 m.
  1. Step 1 — Calculate the mean absolute difference: mean = sum of differences ÷ number of comparisons = 11.25 m ÷ 45 = 0.25 m.
  2. Step 2 — Compare to the allowable limit: 0.25 m < 0.50 m.
  3. Step 3 — State the standard deviation: 0.18 m is also less than the allowable limit.
  4. Step 4 — Write the compliance statement: The cross-line mean difference of 0.25 m and standard deviation of 0.18 m are both within the IHO Order 1 allowable limit of 0.50 m at 10 m depth. This survey meets IHO Order 1 at the 95% confidence level.
Answer: Mean difference = 0.25 m; standard deviation = 0.18 m; both values are below the 0.50 m threshold, so the survey meets IHO Order 1.
2. Calculate the IHO Order 1a TVU allowable limit at a depth of 20 m, using the formula TVU = √(a² + (b × d)²), where a = 0.5 m and b = 0.013.
  1. Step 1 — Calculate the depth-dependent term: b × d = 0.013 × 20 = 0.26 m.
  2. Step 2 — Square each component: a² = 0.5² = 0.25; (b × d)² = 0.26² = 0.0676.
  3. Step 3 — Sum the squares: 0.25 + 0.0676 = 0.3176.
  4. Step 4 — Take the square root: √0.3176 ≈ 0.564 m.
  5. Step 5 — State the result: The maximum allowable TVU at 20 m depth under IHO Order 1a is approximately 0.56 m at the 95% confidence level.
Answer: TVU ≈ 0.56 m at 20 m depth under IHO Order 1a.
3. A student survey collected 3,840 soundings over a polygon. During processing, 192 soundings were flagged as outliers and rejected. Calculate the rejection percentage and assess whether it is reasonable (generally, rejection rates above 10% warrant investigation of instrument or vessel issues).
  1. Step 1 — Calculate rejection percentage: (rejected ÷ total) × 100 = (192 ÷ 3,840) × 100 = 5.0%.
  2. Step 2 — Compare to the 10% guideline: 5.0% < 10%.
  3. Step 3 — Report in the data-quality form: 192 soundings rejected (5.0%); this is within an acceptable range and does not indicate a systematic instrument or vessel problem.
Answer: Rejection rate = 5.0%; acceptable under the 10% guideline; include this figure in the data-quality statement.
4. A tide gauge recorded a water level of +1.8 m above MLLW at the time of a sounding. The echosounder measured a depth of 6.4 m below the water surface. What is the corrected chart depth (depth below MLLW)?
  1. Step 1 — Understand the correction: chart depth = measured depth + gauge reading above MLLW (water level is higher than datum, so the true depth below MLLW is greater than the measured depth below the current surface).
  2. Step 2 — Apply the correction: chart depth = 6.4 m + 1.8 m = 8.2 m.
  3. Step 3 — State the result: The corrected sounding to be recorded on the chart is 8.2 m below MLLW.
Answer: Corrected chart depth = 8.2 m below MLLW.

The math in this lesson1

Learners compute a 0.25 m mean cross-line difference (11.25 m / 45) and compare it and the SD to 0.50 m.
S-ID.2
Brush up in the math halls at newSchoolWorks.com:
In class: Students organize all project documentation into the required NOAA report structure sections: project overview, vessel and equipment records, processing log, tidal correction summary, data-quality assessment (cross-line statistics), and appendices of raw data files; instructor reviews draft outline before writing begins · Students write the data-quality statement by populating a standard form with their actual cross-line mean difference, standard deviation, total soundings collected, rejected, and percentage coverage of the survey polygon; they compare their values to IHO Order 1 thresholds and state whether the survey meets or does not meet the standard · Oral presentation (10 minutes per student): student presents the survey area map, methodology, data-quality results, and one recommendation for improving coverage or accuracy; class asks at least two questions; instructor grades using a presentation rubric
Materials: NOAA Hydrographic Survey Specifications and Deliverables (current edition, free online), student project files from all previous lessons, word processor, ArcGIS Pro for final map, presentation software, rubric (instructor-prepared)
Check: Written report graded on rubric: all required sections present, data-quality form completed with actual values, conclusion accurately states IHO compliance; minimum passing score 80%; oral presentation graded separately—student must correctly answer at least one of two instructor questions about methodology or data quality

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

NSPS CST L1-2 field documentation
1. Which section of a NOAA-structured hydrographic field report documents the make and model of the echosounder, transducer frequency, and GPS receiver specifications?
NSPS CST L1-2 data quality
2. A student's cross-line mean difference is 0.62 m. The IHO Order 1 allowable limit at the survey depth is 0.50 m. What must the data-quality statement say?
NSPS CST L1-2 vertical datums
3. What is the chart datum used on US nautical charts to which hydrographic soundings are typically reduced?
NSPS CST L1-2 accuracy standards
4. Using the IHO Order 1a formula TVU = √(a² + (b × d)²) with a = 0.5 m and b = 0.013, what is the allowable TVU at a depth of 0 m (ignoring the depth-dependent term)?
Esri ArcGIS Pro metadata
5. Why must metadata accompany every geospatial deliverable in a hydrographic report?
NSPS CST L1-2 data quality
6. A student collected 5,200 soundings and rejected 780. What is the rejection percentage, and does it warrant investigation of instrument issues?
NSPS CST L1-2 field operations
7. During a 10-minute oral presentation, an instructor asks: 'Why did you reject 45 soundings near the vessel's turn?' The best professional response is to:
NSPS CST L1-2 report documentation
8. Which item belongs in the appendices of a hydrographic field report rather than in the main body?
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