Hydraulic head

Hydraulic head

Headpressure

USGS-Armenia, March 2, 2016, Ararat Valley 05

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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

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

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

Hydraulic head is used in various fields, including:

• Groundwater hydrology: To determine the direction and rate of groundwater flow.
• Hydraulic engineering: For the design and analysis of dams, levees, and canals.
• Environmental engineering: To assess the movement of contaminants in groundwater.

Measurement

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

• 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

• Hydrology
• Groundwater
• Piezometer
• Darcy's law
• Aquifer
• Hydraulic gradient