Definitions for

**"Hydraulic Gradient"****Related Terms:**Hydraulic head, Groundwater divide, Piezometric surface, Downgradient, Head, Hydraulic grade line, Piezometer, Drawdown, Water table, Static head, Static water level, Potentiometric surface, Spring , Artesian, Interflow, Hydrostatic head, Water level, Water-table, Percolation rate, Cone of depression, Hydraulic conductivity, Head loss, Induced recharge, Groundwater table, Capillary fringe, Artesian well, Artesian water, Throughflow, Discharge area, Transmissivity, Unconfined aquifer, Sink, Phreatic, Seepage, Seep, Saturated zone, Water column, Fountain, Subirrigation, Zone of saturation, Vadose, W.c, Perched water, Perched water table, Recharge area, Drip irrigation, Groundwater level, Ground water, Groundwater, Groundwater recharge

Slope of a water table or potentiometric surface. More specifically, change in head per unit of distance in a given direction, generally the direction of the maximum rate of decrease in head. The difference in hydraulic head divided by the distance along the flowpath.

The difference in potential between two points, divided by the lateral distance between the points.

The difference in hydraulic head between any two points (represented by a difference in water level) defines the 'hydraulic gradient' between those points.

An imaginary line through the points to which water would rise in a series of vertical tubes connected to the pipe. In an open channel, the water surface itself is the hydraulic grade line.

The slope of the water surface in an aquifer. The hydraulic gradient indicates the direction groundwater will flow. Water always flows from higher water table elevations to lower water table elevations. All other factors being equal, flow is greater when the hydraulic gradient is steeper.

The slope of the hydraulic grade line; the rate of change (e.g., rise or fall) of pressure head; the ratio of the loss in the sum of pressure head and position head to the flow distance. For open channels, it is the slope of the water surface (It is frequently considered parallel to the channel invert, but that can happen only if uniform flow occurs). For closed conduits under pressure, it is the slope of the line joining the elevations to which water would rise in pipes freely vented and under atmospheric pressure. A positive slope is usually one which drops in the direction of flow.

Related Topics: [ structures] Rate of energy loss per unit of distance; in Manning equation, fall (gravitational energy loss) per unit length.

The change in hydraulic head (pressure) per unit distance in a given direction (dimensionless). It is the driving force of fluid flow in a porous medium.

the prevailing inclination of the water table or piezometric surface which provides the driving force to transmit groundwater through an aquifer.

Hydraulic Gradient - The change in energy along a flow line in an unconfined or confined aquifer.

The direction of ground water flow due to changes in the depth of the water table.

(3) the slope of the free surface of water in a stream flowing in an open channel.

the change in total potentiometric (or piezometric) head between two points divided by the horizontal distance separating the two points.

Water level from a given point upstream to a given point downstream; or the height of the water surface above a subsurface point. Used in analysis of both ground- and surface-water flow, and is an expression of the relative energy between two points.

Change in head (i.e., water pressure) per unit distance in a given direction, typically in the principal flow direction.

The surface slope of a liquid in a pipeline. This is generally taken as parallel to the invert in a smaller gravity sewer, but it must be checked. In a treatment works this will be the overall head losses.

Slope of a water table or potentiometric surface. Groundwater flows from points of high elevation and pressure to points of low elevation and pressure. The difference in hydraulic head divided by the distance along the flowpath.

The slope of the water table at a particular point.

The slope of the water surface in an open stream system, or the change in elevation of the water table (piezometric surface) in a subsurface saturated (groundwater) system

slope of the water table or potentiometric surface.

The slope of the surface of open or underground water.

The head loss per unit distance of flow.

In an aquifer, the rate of change of total head per unit of distance of flow at a given point and in a given direction. In a stream, the slope of the hydraulic grade line.

The change in pressure head between any two points along a line of flow divided by the length between the points.

In general, the direction of groundwater flow due to changes in the depth of the water table.