Groundwater withdrawal wells create a cone of depression, which is characterized by an increasing gradient with increasing proximity to the well. To represent this situation in a model adequately, a radially symmetric refinement is required around the well. As the gradient which has to be described increases with the approach to the well, an exponential refinement is advantageous.
The parameters of the refinement must be chosen depending on the hydraulic conditions. Thus areas with a low permeability and thus a strong lowering of the groundwater level require a small inner radius (e.g. 2 m) but only a small outer radius (e.g. 50 m) as well.
In flat cones of depressions these parameters can be set higher. Based on the distance of the inner radius of the well, the nodes are arranged radially symmetrical with exponentially increasing distance to the well, until the desired outer radius is reached or exceeded.
The well parameters are determined within working on the contours during the mesh generation. Via Contour 
Edit p-contours well parameters and after selecting the appropriate node, an input window appears where the parameters are entered. The following figure shows the relationship between the parameters and the element mesh refinement:
Radial symmetrical arrangement of nodes during the well discretization
Representing horizontal filter wells, the individual lines have to be considered in the discretization. Each line should be represented by multiple nodes with a distance of 5 m to 10 m. An exponential mesh refinement as in vertical wells is not necessary because groundwater drawdowns in horizontal filter wells are more areally developed. The distribution of the total amount of withdrawal should not be equally on all nodes, but in a way that a highly uniform potential distribution results at each line.