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A drainage equation is an equation describing the relation between depth and spacing of parallel subsurface drains, depth of the watertable, depth and hydraulic conductivity of the soils. It is used in drainage design. Parameters in Hooghoudt's drainage equation. A well known steady-state drainage
Drainage options for the construction industry include: Point drainage, which intercepts water at gullies (points). Gullies connect to drainage pipes beneath the ground surface, so deep excavation is required to facilitate this system. Support for deep trenches is required in the shape of planking, strutting or shoring.
The energy balance of groundwater flow can be applied to flow of groundwater to subsurface drains. [2] The computer program EnDrain [3] compares the outcome of the traditional drain spacing equation, based on Darcy's law together with the continuity equation (i.e. conservation of mass), with the solution obtained by the energy balance and it can be seen that drain spacings are wider in the ...
According to Montgomery and Dietrich’s equation, drainage density is a function of vertical hydraulic conductivity. Coarse-grained sediment like sand would have a higher hydraulic conductivity and are predicted by the equation to form a relatively higher drainage density system than a system formed by finer silt with a lower hydraulic ...
Spacing equations of subsurface drains and the groundwater energy balance applied to drainage equations [5] are examples of two-dimensional groundwater models. Three-dimensional models like Modflow [6] require discretization of the entire flow domain. To that end the flow region must be subdivided into smaller elements (or cells), in both ...
Flux F through a surface, dS is the differential vector area element, n is the unit normal to the surface. Left: No flux passes in the surface, the maximum amount flows normal to the surface.
A newer method that allows 1-D groundwater and surface water coupling in homogeneous soil layers and that is related to the Richards equation is the Finite water-content vadose zone flow method solution of the Soil Moisture Velocity Equation. In the case of uniform initial soil water content and deep, well-drained soil, some excellent ...
An example of these efforts was developed at the Southeast Water Laboratory, [19] one of the first attempts to calibrate a surface runoff model with field data for a variety of chemical contaminants. The attention given to surface runoff contaminant models has not matched the emphasis on pure hydrology models, in spite of their role in the ...