Terms Flashcards
The science of measurement, configuration, and mapping of bodies of water with special consideration for their use in navigation
Hydrography
A chart containing information regarding the characteristics and topography of the underlying water bed which are primarily important to underwater surveying works and navigation.
Hydrographic Chart
Office plots of all field data gathered during the survey. These sheets represent the data after all corrections have been applied.
Smooth sheet
The rise and fall of water surface due to the gravitational attraction of the sun and the moon on the earth.
Tide
It refers to the maximum height of water above the reference plane during a given period.
High tide
It refers to the current flow direction.
Set
It refers to the lowest possible height of the water surface below the reference plane during a given period.
Low tide
The period within which the water surface is moving ashore.
Flood tide
The period within which the water surface subsides and flows back to the sea.
Ebb tide
Office plots of all field data gathered during the survey. These sheets represent the data after all corrections have been applied.
Smooth sheet
Which map projection has distances correct on the central meridian but the east and west extremities are distorted?
Transverse Mercator
A map projection showing each parallel of latitude as the arc of the circle whose radius is equal to the length of the tangent extending from the parallel to a point of intersection with the earth’s axis?
Polyconic
The projection least suited for general use in an office and giving very inaccurate information as to relative size of areas in widely different latitudes.
Mercator
The determination of the water depth at a certain fixed point.
Sounding
A piece of weight usually solid metal used to fix the sounding line in a vertical position.
Smooth Lead
A wire or a rope across the river attached to the two poles at the river banks and used hold the boat in place.
Stay line
An instant in which the tidal current is changing its direction and flows neither in or out.
Slack water
It refers to the speed of the current flow.
Drift
The art of making measurements of the flow of water in open channels
Stream Gaging
The selected site on a stream which is occupied and operated so as to furnish the basic data from which systematic records of discharge can be derived.
Gaging station
Used to locate wrecks, rocks, and other navigational hazards.
Wire drag
Undesired minerals associated with ore.
Gangue
The transverse Mercator is best suited for locations
having predominant North-South Length
The Lambert Conformal Projection is (according to method of construction)
Conic
The magnitude of scale error for an area mapped by a Lambert Conformal Projection is fixed by the:
North and South limitation chosen
On a globe, rhumb line is a
Spiral
The area to be mapped must be small, and long and narrow, with the long axis in the direction of a meridian or parallel, when using
British Grid
Which grid has the most suitable projection for over-all coverage?
Transverse Mercator
Which grid system considers the portion of the earth between two selected parallels of latitude to be a horizontal slice of cone?
Orthomorphic
Which one of the following projections requires a separate computation and a map for each city or base upon which the map is centered
Azimuthal Equidistant
Every parallel of latitude is represented on a map by the development circumference of the base of a right cone tangent to the earth at that parallel in the projection
Polyconic
Colors used for water or hydrographic features such as reservoirs, rivers, lakes, canals, marshes, ponds, and wetlands.
Blue
Color used for all man-made or cultural features, political subdivision, place names, grid lines, and letterings on the map.
Black
Color used as a surface tint or cover overlay for wooded areas and other forms of vegetation. It is used to show features such as trees, grass, orchards, vineyards, etc.
Green
Color used to emphasize important roads and public subdivision lines.
Red
Color used as a surface tint to portray built-up urban areas and the area coverage of large cities.
Pink
Color used sometimes in place of brown.
Gray
A full headed and full feathered arrow represents.
True Meridian
A half headed and half feathered arrow represents.
Magnetic Bearing
Map scales having scales of 1:10000, or smaller and with contour intervals ranging from 5 to 2,000 meters.
Small-scale maps
Map scales having scales ranging from 1:2000 to 1:10,000 and with contour intervals ranging from 1.0 to 5.0 meters. They are also referred to as the intermediate scales.
Medium Scale Maps
Map scales having scales of 1:2000 or larger and with contour intervals ranging from 0.1 to 2 meters
Large-Scale Maps
A style of letters which have heavy strokes consisting of heavy and light lines.
Roman Letters
A style of letters or the lines of the letters which are composed of uniform width strokes. It is used for titles and in identifying hypsographic names such as mountains, valleys, and hills. They are widely used when a heavy weight and finished appearance are desired and may be drawn vertical or inclined.
Gothic Letters
A style of letters or single stroke letters which are most easily and rapidly made and are standard practice for fieldnotes and notations on maps and drawings.
Reinhardt Letters
It refers to all identifiable features of the earth’s surface, whether natural or artificial, which can be assigned to a specific position
Topography
A representation of the earth’s surface in 3 dimensions. It shows the same features as a planimetric map and in addition indicates relief, usually by means of contours which is its distinguishing characteristic.
Topographic Maps
A representation of the earth’s surface in two horizontal dimensions only. They are useful in indicating locations, horizontal distances, and in finding directions, but it is of no value to a user whose primary concern is with the topographic or relief features of the land.
Planimetric Map