Hydraulic head

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Hydraulic head
Headpressure
USGS-Armenia, March 2, 2016, Ararat Valley 05
relation between heads hydrostatic
relation between heads flowing

Hydraulic head

Hydraulic head is a specific measurement of liquid pressure above a geodetic datum. It is usually measured as a liquid surface elevation, expressed in units of length, at the entrance of a piezometer. Hydraulic head is a key concept in hydrology, hydraulics, and civil engineering, particularly in the study of groundwater flow and the design of water supply systems.

Definition[edit | edit source]

Hydraulic head is defined as the height of a liquid column that corresponds to the pressure exerted by the liquid at a given point. It is a measure of the potential energy available to drive the flow of water in a hydraulic system. The hydraulic head (h) at a point in a fluid is given by the equation:

h = z + \frac{p}{\gamma}

where:

  • z = elevation head (height above a reference datum)
  • p = pressure head (pressure at the point)
  • \gamma = specific weight of the fluid

Components[edit | edit source]

Hydraulic head consists of two main components:

  • Elevation head: The height of the point above a reference level, usually mean sea level.
  • Pressure head: The height of a fluid column that would produce the pressure exerted by the fluid at the point of measurement.

Applications[edit | edit source]

Hydraulic head is used in various fields, including:

Measurement[edit | edit source]

Hydraulic head is typically measured using a piezometer, which is a device that measures the pressure head of groundwater at a specific point. The elevation head is determined by the height of the piezometer above a reference datum.

Related Concepts[edit | edit source]

  • Hydraulic gradient: The slope of the hydraulic head in a given direction, which drives the flow of water.
  • Darcy's law: A fundamental equation that describes the flow of a fluid through a porous medium, which is driven by the hydraulic gradient.
  • Aquifer: A geological formation that can store and transmit groundwater, characterized by its hydraulic head distribution.

See Also[edit | edit source]

References[edit | edit source]

External Links[edit | edit source]

Contributors: Prab R. Tumpati, MD