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  2. Drainage equation - Wikipedia

    en.wikipedia.org/wiki/Drainage_equation

    the permissible long term average depth of the water table (Dw) on the basis of agricultural drainage criteria; the soil's hydraulic conductivity (Ka and Kb) by measurements; the depth of the bottom of the aquifer (Di) the design drain spacing (L) can be found from the equation in dependence of the drain depth (Dd) and drain radius (r ...

  3. Water table - Wikipedia

    en.wikipedia.org/wiki/Water_table

    A plot of sugarcane yield versus depth of water table in Australia. The critical depth is 0.6 m. [4] [5] Most crops need a water table at a minimum depth. [6] For some important food and fiber crops a classification was made [7] because at shallower depths the crop suffers a yield decline. [8]

  4. Watertable control - Wikipedia

    en.wikipedia.org/wiki/Watertable_control

    In geotechnical engineering, watertable control is the practice of controlling the height of the water table by drainage.Its main applications are in agricultural land (to improve the crop yield using agricultural drainage systems) and in cities to manage the extensive underground infrastructure that includes the foundations of large buildings, underground transit systems, and extensive ...

  5. How to best filter your L.A. tap water based on your ZIP Code

    www.aol.com/news/best-filter-l-tap-water...

    How to determine your water quality. ... When I typed my own Silver Lake ZIP Code in for a water quality analysis, the results did not put me at ease. ... you can run a more in-depth test. The ...

  6. Drawdown (hydrology) - Wikipedia

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

    Air line method is a convenient and nonintrusive method used to measure water levels that is often used for the repeated testing of wells over 300 feet deep. [13] This method obtains water table depth using a pressure gauge and water displacement. [14] Wetted tape method is a commonly-used method for measuring water levels up to roughly 90 feet ...

  7. Standard step method - Wikipedia

    en.wikipedia.org/wiki/Standard_Step_Method

    The only way to do this on a mild reach is to follow an M1 profile. The same logic applies downstream to determine that the water surface follows an M3 profile from the gate until the depth reaches the conjugate depth of the normal depth at which point a hydraulic jump forms to raise the water surface to the normal depth.

  8. Pore water pressure - Wikipedia

    en.wikipedia.org/wiki/Pore_water_pressure

    If the water table is at depth d w in fine-grained soils, then the pore pressure at the ground surface is: [4] =, where: p g is the unsaturated pore water pressure (Pa) at ground level, g w is the unit weight of water (kN/m 3), = / d w is the depth of the water table (m),

  9. 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 ...