Drains

Tile drains can be represented as equivalent boundary conditions in two-dimensional domains is based on studies by Vimoke et al. [1963] and Fipps et al. [1986]. The approach uses results of electric analog experiments conducted by Vimoke and Taylor [1962] who reasoned that drains can be represented by nodal points in a regular finite element mesh, provided adjustments are made in the hydraulic conductivity of neighboring elements. This approach assumes that the node representing a drain must be surrounded by finite elements (either triangular or quadrilateral) which form a square whose hydraulic conductivities are adjusted. This method of implementing a drain by means of a boundary condition gives efficient, yet still relatively accurate, predictions of the pressure head in the immediate area surrounding the drain, as well as of the drain flow rate [Fipps et al., 1986].

Similarly as for a seepage face, HYDRUS assumes that as long as a drain is located in the saturated zone, the pressure head along the drain will be equal to zero; the drain then acts as a pressure head sink. However, the drain will behave as a nodal sink/source with zero recharge when located in the unsaturated zone.

The following Drain Parameters must be specified in the pop-up window: effective diameter of the drain and a reduction in the correction factor Cd.

Additional information about other Domain Properties.