In the confined aquifers of the lower alluvial plains the fine grain size of the sediments (sands and silts) and the chemical-physical characteristics of the groundwater (reducing environment with high levels of dissolved iron and manganese) have important consequences on the service life and efficiency of water wells; these are often affected by clogging phenomena of the well screen, caused by physical, chemical, and biochemical (biofouling) processes. Typical symptoms are the progressive lowering of dynamic level and operating flow rate, with a consequent reduction of the specific capacity parameter. Occlusion of the gravel pack and well screen causes a progressive reduction in the efficiency and productivity of the well, with negative effects on the quantity and quality of the produced water.
The work analyses a case study in the lower Po Plain (Province of Ferrara) where the presence of a drinking water well field has allowed the collection of a significant hydrogeological data set, especially in recent years, thanks to continuous flow rate and groundwater level measurement systems. In particular, the temporal evolution of the specific capacity parameter is evaluated, analysing the possible dependencies on the construction characteristics of the wells, the boundary conditions and the local geochemical characteristics of the aquifer, in order to formulate hypotheses on the physical, chemical and biochemical processes involved and to obtain useful indications for the management and scheduled maintenance of the wells.