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  2. Standard step method - Wikipedia

    en.wikipedia.org/wiki/Standard_Step_Method

    Table 1: Spreadsheet of Newton Raphson Method of downstream water surface elevation calculations Step 5: Combine the results from the different profiles and display. Normal depth was achieved at approximately 2,200 meters upstream of the gate. Step 6: Solve the problem in the HEC-RAS Modeling Environment:

  3. Drainage equation - Wikipedia

    en.wikipedia.org/wiki/Drainage_equation

    One would not want the water table to be too shallow to avoid crop yield depression nor too deep to avoid drought conditions. This is a subject of drainage research. The figure shows that a seasonal average depth of the water table shallower than 70 cm causes a yield depression [5] The figure was made with the SegReg program for segmented ...

  4. Biological monitoring working party - Wikipedia

    en.wikipedia.org/wiki/Biological_monitoring...

    The biological monitoring working party (BMWP) is a procedure for measuring water quality using families of macroinvertebrates as biological indicators. [1]The method is based on the principle that different aquatic invertebrates have different tolerances to pollutants.

  5. Water retention curve - Wikipedia

    en.wikipedia.org/wiki/Water_retention_curve

    Water retention curve is the relationship between the water content, θ, and the soil water potential, ψ. The soil moisture curve is characteristic for different types of soil, and is also called the soil moisture characteristic. It is used to predict the soil water storage, water supply to the plants (field capacity) and soil aggregate stability.

  6. Parshall flume - Wikipedia

    en.wikipedia.org/wiki/Parshall_flume

    Only the upstream depth needs to be measured to calculate the flow rate. A free flow also induces a hydraulic jump downstream of the flume. Submerged flow occurs when the water surface downstream of the flume is high enough to restrict flow through a flume, submerged flume conditions exist. A backwater buildup effect occurs in a submerged flume.

  7. Pitzer equations - Wikipedia

    en.wikipedia.org/wiki/Pitzer_equations

    They can be used to calculate mixed ion activity coefficients and water activities in solutions of high ionic strength for which the Debye–Hückel theory is no longer adequate. They are more rigorous than the equations of specific ion interaction theory (SIT theory), but Pitzer parameters are more difficult to determine experimentally than ...

  8. Groundwater flow equation - Wikipedia

    en.wikipedia.org/wiki/Groundwater_flow_equation

    The above groundwater flow equations are valid for three dimensional flow. In unconfined aquifers, the solution to the 3D form of the equation is complicated by the presence of a free surface water table boundary condition: in addition to solving for the spatial distribution of heads, the location of this surface is also an unknown. This is a ...

  9. Hazen–Williams equation - Wikipedia

    en.wikipedia.org/wiki/Hazen–Williams_equation

    The Hazen–Williams equation is an empirical relationship that relates the flow of water in a pipe with the physical properties of the pipe and the pressure drop caused by friction. It is used in the design of water pipe systems [1] such as fire sprinkler systems, [2] water supply networks, and irrigation systems.