Hydrographic Surveying

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Hydrographic Surveying

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is defined as the process of measuring and Information gathering concerning bodies of water that are necessary in the preparation of nautical chart.

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Hydrography

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is the science of measurements, configuration and mapping of bodies of water with special consideration to their use in navigation.

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Hydrographic Chart

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is a chart containing information regarding the characteristic and topography of the underlying water bed which are preliminary important to underwater surveying works and navigation.

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Smooth Sheet

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are office plots of all field data gathered during the survey. These sheets represent the data after all correction have been applied.

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Holidays

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unsurveyed portion of bodies of water.

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Tide

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is the rise and fall of water surface due to the gravitational attractions of the sun, and the moon to the earth.

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High Tide

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refers to the maximum height of the water surface below the reference plane during a given period.

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Low Tide

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refers to the lowest possible height of the water surface below the reference plane during a given period.

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Set

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refers to the current flow direction.

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Flood Tide

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the period within which the water surface is moving ashore.

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Ebb Tide

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the period within each the water surface subsides and flows back to the sea.

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Sounding

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is the determination of water depth at a certain fixed point.

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Sounding Load

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is a piece of weight usually solid metal used to fix the sounding line in vertical position.

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Tag Line

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is a wire or a rope across the river attached to the two poles at the river bank mark with numbers indicating its position from its initial point.

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Stay Line

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is a piece of wire or rope attached to the poles at the river banks and used to hold the boat in place.

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Slack Water

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the instant at which the tidal current is changing its direction and flows neither in nor out.

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Drift

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refers to the speed of the current flow.

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Stream Gaging

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is the art of making measurements of the flow of water in open channels.

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Gaging Station

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is a selected site on stream which is equipped and operated so as to furnish the basic data from which systematic records of discharge can be derived.

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Current Meter

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is an instrument used in measuring the velocity of the water flowing in a river section.

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Wire Drag

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is used to locate the wrecks pinnacle rocks and other navigational hazards.