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Project Control, Coordinate Systems and Datums
SPCS is an acronym for ____________________.
State Planed Control Systems
State Plane Coordinate Systems
WGS is an acronym for ________________________.
World Geodetic System
World Geographic System
Most engineering and construction work including dredging is aligned to a local project coordinate system and the datum for such local systems is typically a reference monument/baseline.
On some navigation projects, the offset coordinate is termed a _________________and is defined relative to the project centerline or, in some instances, the channel-slope intersection line (toe).
The ______________ reference plane is not a flat surface but slopes as a function of the tidal range in the area.
Depending on the magnitude of the tidal range and linearity of the slope, recording gages may need to be placed at 0.5- to 5-mile increments along the project.
River datums are referenced to a ____________________________.
Low water reference plane (LWRP)
Mean Lower Low Water (MLLW)
The ________________ represents a low water datum from which navigation is maintained.
________________________datums are used as a reference on NOS nautical charts.
The International Great Lakes Datum of 1955 is a geodetic datum derived from an adjustment of the first order level network of Mexico.
Long-term tide stations are referred to as primary control tide stations. These are tide stations at which continuous observations have been made over a minimum 19-year Metonic cycle.
Short-term tide stations are referred to as ______________tide stations.
The National Tidal Benchmark System (NTBMS) does not provides datum information for previously occupied tidal measurement locations.
______________________ is a method that involves interpolation between two existing sites where tidal datums were previously determined.
NGVD/MLLW differential method
Operating tide stations
Operating tide stations method involves situations in which existing tidal datums are not reliable, are too far from the project site, or do not exist.
The purpose of the ___________ is to record continuous times and water level heights at the site.
______________________was officially established in January 1992, replacing IGLD 55.
Controlled portions of the Mississippi are referred to pool levels between the controlling structures.
______________ zoning is the practice of dividing a hydrographic survey area into discrete zones or sections, each one possessing similar tidal characteristics.
Water surface fluctuations at a gage should not be stilled so that the maximum range of water rise and fall with one wave passage is negligible.