11137 version 5

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Process tidal data

Level / 5
Credits / 6

PurposeThis unit standard is for people working in the hydrography sector of the surveying profession.

People credited with this unit standard are able to: demonstrate knowledge of tidal theory; select and establish a vertical datum for tidal data reduction; and demonstrate knowledge of, and apply co-tidal factors to tidal readings.

Subfield / Surveying
Domain / Hydrography
Status / Registered
Status date / 25 February 2008
Date version published / 25 February 2008
Planned review date / 31 December 2012
Entry information / Open.
Accreditation / Evaluation of documentation and visit by NZQA and industry.
Standard setting body (SSB) / Infrastructure ITO
Accreditation and Moderation Action Plan (AMAP) reference / 0101

This AMAP can be accessed at

Special notes

Documentation relevant to this unit standard includes but is not limited to:

TH Standard 31 Standards for Hydrographic Surveys (HYSPEC) v3(Wellington: National Topographic/Hydrographic Authority, 2001), available at

IHO Standards for Hydrographic Surveys, Special Publication No 44 (Monaco: International Hydrographic Organisation, 1998) (IHO standards), available at

tide tables available from the tidal information pages in the hydrography section at

Garrison, Tom. Oceanography: An Invitation to Marine Science, Sixth edition(Belmont, CA: Thomson Brooks/Cole, 2007);

Prager, Ellen J, with Earle, Sylvia A,The Oceans(New York: McGraw-Hill, 2000);

Summerhayes, C P, and Thorpe, SA. Oceanography, An Illustrated Guide(New York: John Wiley & Sons, 1996);

Thurman, Harold V, and Trujillo, Alan P,Essentials of Oceanography, Eighth edition (Upper SaddleRiver, NJ: Prentice Hall, 2005).

Elements and performance criteria

Element 1

Demonstrate knowledge of tidal theory.

Performance criteria

1.1The tide generating forces and principal tidal constituents are explained in accordance with the laws of physics and static and dynamic tidal theory.

1.2The factors modifying the theoretical tide are explained in accordance with static and dynamic tidal theory.

Rangemeteorological resonance, land mass, astronomical influence, Coriolis force.

1.3Specific examples of modified tides are explained in accordance with static and dynamic tidal theory.

Rangemodified tides – surges, negative surges, bores, seiches, diurnal tides, amphidromic points.

1.4Factors in the analysis and prediction of tides are identified and explained in accordance with tidal theory.

Element 2

Select and establish a vertical datum for tidal data reduction.

Rangeone of – mean high water springs, mean sea level, mean low water springs, lowest astronomical tide, sounding datum, chart datum.

Performance criteria

2.1A vertical datum is selected which enables reference levels to be determined for soundings, heights, and clearances.

2.2Sounding datum is established by transfer to or from a site benchmark in accordance with HYSPEC.

2.3The connection between recorded tidal height and sounding datum is determined in accordance with HYSPEC.

Element 3

Demonstrate knowledge of, and apply co-tidal factors to tidal readings.

Performance criteria

3.1Factors affecting co-tidal data are determined from tidal observations within the survey area.

Rangefactors – time, height, location of tidal measurement sites, wave fronts.

3.2Requirements for co-tidal charts are identified in accordance with HYSPEC.

Rangestandard port, secondary port.

Please note

Providers must be accredited by NZQA, or an inter-institutional body with delegated authority for quality assurance, before they can report credits from assessment against unit standards or deliver courses of study leading to that assessment.

Industry Training Organisations must be accredited by NZQA before they can register credits from assessment against unit standards.

Accredited providers and Industry Training Organisations assessing against unit standards must engage with the moderation system that applies to those standards.

Accreditation requirements and an outline of the moderation system that applies to this standard are outlined in the Accreditation and Moderation Action Plan (AMAP). The AMAP also includes useful information about special requirements for organisations wishing to develop education and training programmes, such as minimum qualifications for tutors and assessors, and special resource requirements.

Comments on this unit standard

Please contact Infrastructure you wish to suggest changes to the content of this unit standard.

 New Zealand Qualifications Authority 2018