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  2. Water balance - Wikipedia

    en.wikipedia.org/wiki/Water_balance

    The water balance is also referred to as a water budget. Developing water budgets is a fundamental activity in the science of hydrology. According to the US Geological Survey: [4] An understanding of water budgets and underlying hydrologic processes provides a foundation for effective water-resource and environmental planning and management.

  3. Chart datum - Wikipedia

    en.wikipedia.org/wiki/Chart_datum

    Tide tables give the height of the tide above a chart datum making it feasible to calculate the depth of water at a given point and at a given time by adding the charted depth to the height of the tide. One may calculate whether an area that dries is under water by subtracting the drying height from the [given] height calculated from the tide ...

  4. Flood stage - Wikipedia

    en.wikipedia.org/wiki/Flood_stage

    Flood stage is the water level, as read by a stream gauge or tide gauge, for a body of water at a particular location, measured from the level at which a body of water threatens lives, property, commerce, or travel. [1] The term "at flood stage" is commonly used to describe the point at which this occurs.

  5. Water level - Wikipedia

    en.wikipedia.org/wiki/Water_level

    Water level, also known as gauge height or stage, is the elevation of the free surface of a sea, stream, lake or reservoir relative to a specified vertical datum. [1]

  6. Hydraulic head - Wikipedia

    en.wikipedia.org/wiki/Hydraulic_head

    Measuring hydraulic head in an artesian aquifer, where the water level is above the ground surface. Hydraulic head or piezometric head is a specific measurement of liquid pressure above a vertical datum. [1] [2] It is usually measured as a liquid surface elevation, expressed in units of length, at the entrance (or bottom) of a piezometer.

  7. Drawdown (hydrology) - Wikipedia

    en.wikipedia.org/wiki/Drawdown_(hydrology)

    Static level is the level of water in the well when no water is being removed from the well by pumping. [8] Water table is the upper level of the zone of saturation, an underground surface in which the soil or rock is permanently saturated with water. [9] Well yield is the volume of water per unit time that is produced by the well from pumping. [8]

  8. Stream gradient - Wikipedia

    en.wikipedia.org/wiki/Stream_gradient

    A stream that flows upon a uniformly erodible substrate will tend to have a steep gradient near its source, and a low gradient nearing zero as it reaches its base level.Of course, a uniform substrate would be rare in nature; hard layers of rock along the way may establish a temporary base level, followed by a high gradient, or even a waterfall, as softer materials are encountered below the ...

  9. Sea level - Wikipedia

    en.wikipedia.org/wiki/Sea_level

    Still-water level or still-water sea level (SWL) is the level of the sea with motions such as wind waves averaged out. [6] Then MSL implies the SWL further averaged over a period of time such that changes due to, e.g., the tides, also have zero mean.