Density stratification

Mixing does not occur in water masses where there are large thermal or chemical differences prevailing. The layers will instead lie on top of one another, depending on their relative densities. The formation of these density stratifications in the water column is a highly complex phenomenon, and arises from the interaction of thermodynamic parameters that mutually influence one another.

The water management and drainage systems of the hard coal mining industry has transformed the original hydrogeological conditions in the Ruhr Area: Numerous shafts and boreholes have created connections between the surface and deep down underground. These shafts convey various amounts of water, depending on their location. Depending on the geology and the tectonics of the surrounding rock and the lining employed in the shafts, flows of heat energy and materials occur between the groundwater reservoir, other geological layers and the atmosphere.

This is why it is essential to analyse the density stratifications in the shafts when planning to allow minewater to ascend within the existing mineworkings following the shut-down event.