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  2. Shields formula - Wikipedia

    en.wikipedia.org/wiki/Shields_formula

    is the water depth; is the gradient (= the slope of the current). It is important to realise that is the shear stress exerted by the flow (i.e. a property of the flow) and is the shear stress at which the grains move (i.e. a property of the grains).

  3. 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.

  4. Runoff curve number - Wikipedia

    en.wikipedia.org/wiki/Runoff_curve_number

    These soils have a very slow rate of water transmission (final infiltration rate less than 0.05 in (1.3 mm) per hour). Selection of a hydrologic soil group should be done based on measured infiltration rates, soil survey (such as the NRCS Web Soil Survey), or judgement from a qualified soil science or geotechnical professional. The table below ...

  5. Soil mechanics - Wikipedia

    en.wikipedia.org/wiki/Soil_mechanics

    soil composition (basic soil material): mineralogy, grain size and grain size distribution, shape of particles, pore fluid type and content, ions on grain and in pore fluid. state (initial): Defined by the initial void ratio , effective normal stress and shear stress (stress history).

  6. Soil gradation - Wikipedia

    en.wikipedia.org/wiki/Soil_Gradation

    In soil science, soil gradation is a classification of a coarse-grained soil that ranks the soil based on the different particle sizes contained in the soil. [1] Soil gradation is an important aspect of soil mechanics and geotechnical engineering because it is an indicator of other engineering properties such as compressibility , shear strength ...

  7. Richards equation - Wikipedia

    en.wikipedia.org/wiki/Richards_equation

    The Richards equation represents the movement of water in unsaturated soils, and is attributed to Lorenzo A. Richards who published the equation in 1931. [1] It is a quasilinear partial differential equation; its analytical solution is often limited to specific initial and boundary conditions. [2]

  8. Sieve analysis - Wikipedia

    en.wikipedia.org/wiki/Sieve_analysis

    A sieve analysis (or gradation test) is a practice or procedure used in geology, civil engineering, [1] and chemical engineering [2] to assess the particle size distribution (also called gradation) of a granular material by allowing the material to pass through a series of sieves of progressively smaller mesh size and weighing the amount of material that is stopped by each sieve as a fraction ...

  9. Proctor compaction test - Wikipedia

    en.wikipedia.org/wiki/Proctor_compaction_test

    At first, the dry unit weight after compaction increases as the moisture content (ω) increases, but after the optimum moisture content (ω opt) percentage is exceeded, any added water will result in a reduction in dry unit weight because the pore water pressure (pressure of water in-between each soil particle) will be pushing the soil ...