If abstraction wells are located near a large receiving watercourse, a certain percentage of bank filtration flows into the wells. To determine this percentage, the attribute KONT can be assigned to the element edges parallel to the receiving water and a flow calculation can be carried out. By visualising the calculated control line rates, the volume flowing to the wells can be determined using the direction of the arrow. The following image shows a section.

Bank filtration rates of the main receiving watercourse

By adding the rates flowing to the wells, the bank filtration rate is calculated as 127946 m³/a. With a withdrawal volume of the entire wellfield of 1450000 m³/a, the bank filtration volume corresponds to a share of approx. 9 %.

Use of control lines to determine the groundwater exfiltration to a receiving watercourse (VORF)