[en] several studies are presently undertaken in the Walloon Region so as to assess the long term environmental impact caused by the shutting down of coal mines and their pumping operations. In many locations, new problems are encountered, such as sudden underground water appearance at hill slopes, coal heaps instability or flooding of underground cellars. Slope instability increase risks. The main goals of the presented studies are to suppress or at least to limit those risks and inconveniences and propose solutions to be implemented in the framework of the existing dewatering facilities built by the Walloon Region and local authorities in mines induced subsidence areas. (authors)