A catchment area is the whole area, from which the flow from the surface and subsurface flows at some point together. This point may be a withdrawal well or the mouth of a water in a receiving water course. The edge of the catchment area is the water divide.

The area is mainly determined by the topographic and geological conditions. The catchment area in a groundwater model can be determined by stream- or path lines or Schlieren or in a transport model by the inverse flow. The procedures are explained in the following.

 

 

Theory of the path line calculation