Australian Water Information Dictionary

Alphabetical list of items

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V

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vadose zone

The areas below the ground where void spaces are filled with a mixture of water under pressure less than atmospheric which includes water held by capillarity and air (gases) under atmospheric pressure.

Source: Poehls DJ and Smith GJ 2009, Encyclopedic dictionary of hydrogeology, Elsevier Inc., 517 pp.

Synonym: unsaturated zone

This definition applies to:

validation

The process of confirming, through provision of objective evidence (including verification and/or [spot checks][1912), that data fulfil the requirements for a specific use or application as agreed with the customer.

Note: Validation will include elements of verification and focuses on the suitability of the end result for the customer. For example, a hydrographer may verify a gauging as part of the validation of a rating for a streamflow site.

This definition applies to:

vapour pressure deficit

The difference between the amount of moisture in the air and how much moisture the air can hold when it is saturated.

Source: Water Regulations 2008 Schedule 3 Part 1. For the latest information on Australian Government law please go to Federal Register of Legislation

This definition applies to:

vector data

Data organised as geometry consisting of points, lines and polygons.

This definition applies to:

velocity extrapolation method

A method of correcting a measured ADVM velocity to a theoretical mean velocity for each ADVM velocity bin (depth cell).

The method involves taking the depth position of the velocity bin and using a velocity profile (e.g. 1/6th power law), the water level, and the bed level to calculate a velocity correction which is applied to each raw ADVM bin velocity. The corrected ADVM velocity bins are then used to calculate a discharge using the mid-section method.

This definition applies to:

VEM

velocity extrapolation method

A method of correcting a measured ADVM velocity to a theoretical mean velocity for each ADVM velocity bin (depth cell).

The method involves taking the depth position of the velocity bin and using a velocity profile (e.g. 1/6th power law), the water level, and the bed level to calculate a velocity correction which is applied to each raw ADVM bin velocity. The corrected ADVM velocity bins are then used to calculate a discharge using the mid-section method.

This definition applies to:

verification

The process of confirming, through provision of objective evidence (e.g. a series of spot checks), that a given measuring instrument or system fulfils specific requirements.

For example, a hydrographer may verify that a measuring instrument is within expected tolerance over the measurement range.

This definition applies to:

vertical

Line on which velocity measurements or depth measurements are made.

Source: AS 3778.1—2009 Clause 2.4. © Standards Australia Limited. Copied by the Australian Government Bureau of Meteorology with the permission of Standards Australia and Standards New Zealand under Licence 1901-c052.

This definition applies to:

vertosols

Clay soils that shrink and swell, and crack as the soil dries. Largest single area occurs in the arid and semi-arid interior of the continent.

Source: R F Isbell, 1996, The Australian Soil Classification, CSIRO Publishing, Melbourne.

This definition applies to:

volume

The volume of water stored at a particular time and date. It excludes the dead storage volume and hence is the volume of water that can be accessed under normal circumstances without the installation of additional infrastructure. See the water storage diagram for more information.

Synonym: accessible storage volume

This definition applies to:

volume weighted average price

The average value (dollars per megalitre) of the water traded where each trade is weighted proportionally by the volume of water (in megalitre) involved in the sale. This provides a more accurate representation of the price (i.e. high volume trades generally attract a ‘bulk discount’).

This definition applies to:

VTG

GPS data string that provides the velocity relative to the ground, including direction and speed.

This definition applies to:

VWAP

volume weighted average price

The average value (dollars per megalitre) of the water traded where each trade is weighted proportionally by the volume of water (in megalitre) involved in the sale. This provides a more accurate representation of the price (i.e. high volume trades generally attract a ‘bulk discount’).

This definition applies to: