Groundwater-systems in mining areas – The influence of water bearing adits

Water bearing adits form a historic near-surface underground drainage and outflow systems whose functionality is of considerable importance in many mining areas all over the world. Water bearing adits are technical structures that have often been in place and in operation for more than two centuries. In most cases, they are no longer accessible directly behind the tunnel portal. Therefore, stable hydraulic, geotechnical and rock mechanical conditions are important, otherwise the hydraulic system would collapse.

In recent years, the Research Centre of Post-Mining has investigated the current situation of a large number of water bearing adits in the southern Ruhr area/Germany. To understand the interaction with the groundwater- systems hydrochemical parameters were analysed, the rate of discharge and of precipitation compared. An essential step is the spatiotemporal evaluation of available mine survey maps of the water bearing adits and the hydraulically connected mine workings. This is needed in order to determine the catchment area of a water bearing adits within the groundwater-system.

To further enhance the process understanding the results from monitoring-stations, special depth-dependent hydrochemical sampling campaigns in former shafts and infiltration/tracer tests in ditches/local streams were integrated. The entire data fusion happened in 3D geological/hydrogeological subsurface models. This integrated subsurface understanding is now the enabler for the implementation of a risk monitoring and management system for this sensitive system of water bearing adits.