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The groundwater flow equation is often derived for a small representative elemental volume (REV), where the properties of the medium are assumed to be effectively constant. A mass balance is done on the water flowing in and out of this small volume, the flux terms in the relationship being expressed in terms of head by using the constitutive ...
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 ...
[5] and it avoids the problem of representative elementary volume by use of a fine water-content discretization and solution method. This equation was converted into a set of three ordinary differential equations (ODEs) [ 5 ] using the method of lines [ 8 ] to convert the partial derivatives on the right-hand side of the equation into ...
Q is the total groundwater discharge ([L 3 ·T −1]; m 3 /s), K is the hydraulic conductivity of the aquifer ([L·T −1]; m/s), dh/dl is the hydraulic gradient ([L·L −1]; unitless), and A is the area which the groundwater is flowing through ([L 2]; m 2) For example, this can be used to determine the flow rate of water flowing along a plane ...
Groundwater is stored in and moves slowly (compared to surface runoff in temperate conditions and watercourses) through layers or zones of soil, sand and rocks: aquifers. The rate of groundwater flow depends on the permeability (the size of the spaces in the soil or rocks and how well the spaces are connected) and the hydraulic head (water ...
In steady state, the level of the water table remains constant and the discharge rate (Q) equals the rate of groundwater recharge (R), i.e. the amount of water entering the groundwater through the watertable per unit of time.
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]
Construction of a flow net is often used for solving groundwater flow problems where the geometry makes analytical solutions impractical. The method is often used in civil engineering, hydrogeology or soil mechanics as a first check for problems of flow under hydraulic structures like dams or sheet pile walls. As such, a grid obtained by ...