Evaluation of mining decommissioning strategies on catchment hydrology

Sediment management can represent a key point for the water resources conservation, as the land use control can limit soil erodibility, ensuring a reduction of the silting volume in the reservoir. This study is focused on the nexus between coal mining activity and the hydrological cycle at the catchment scale, analysing how environmental interventions can be an excellent strategy against the impacts of former mining areas. Lake San Cipriano represents an excellent case study to explore the effects of mining activity on water storage because it is downstream of a river basin in which one of the most important lignite mine in central Italy has worked for years. A hydrological model is implemented on the Soil Water Assessment Tool (SWAT) to choose which decommissioning strategies brings the best results in terms of water resource conservation. Since no flow data are available, the model is calibrated in the solid transport equations, pointing to the convergence of the silting volume in the lake, which has been estimated thanks to multiple bathymetric campaigns carried out over the years. Two environmental restoration scenarios have been analysed: the first is only focused in the land use change with the afforestation of native plants; the second is a wider landscape restoration project that include also river bodies rehabilitation. The results show the quantitative effects of the proposed decommissioning strategies, showing the strong reduction of solid transport and reservoir silting in the two proposed scenarios.