Groundwater use IWB Lange Erlen, verification of protection zones

The IWB (Industrielle Werke Basel) operates various groundwater pumping and infiltration wells in the Lange Erlen area for the drinking water supply of the city of Basel and its surrounding communities. According to the IWB's General Water Supply Plan (GWP), the existing protection zones must be reviewed and adapted. The IWB commissioned HOLINGER AG and TK CONSULT AG to verify and redesignate the protection zones.

The existing 3d groundwater model was preliminary updated and recalibrated. It reliably reproduces the measurements with respect to mean groundwater heights and frequency.

In cooperation with the IWB, numerous transient groundwater scenarios were defined, which represent hydrological and operational extreme conditions (high or low water as well as failure of the recharges and high demand). Within each scenario, 10-day flow lines were calculated for different periods. From the resulting multitude of flow lines, the enclosing surface was generated. It finally serves as the basis for the definition of the protection zones.