Engineering geology, geotechnics and hydrogeology in environmental management: Northern Italian experiences

The area considered belongs to northern Italy and corresponds to the Northern Apennine and Po Plain sectors included within the administrative district of Modena. In this area the width of the Apennine chain from crest to plain is about 45 km, with altitudes ranging from 2,000 m above sea level along the main watershed to 150 m at the foot of the hills. The adjacent plain, characterised by an extremely flat surface, is 150 to 10 m above sea level. A distance of 60 km stretches between the Apennine margin and the River Po course. From a geological point of view the Apennines represent a chain of recent formation, still subject to orogenetic uplift. The plain derives from the deposition of sediments arranged in alluvial fans and river flooding deposits ranging from pebbles to clays in particle size. Vast landslides, mostly due to earth flows but also slides and slumps and deep-seated gravitational deformations are very frequent in the study area and often interest transport infrastructures and urban centres. The restoration and remedial methods are also described. The plain areas are subject to flooding, owing to the rivers’highwaters which are now mitigated thanks to the construction of flood-protection dams. Other problems affecting the plain arise as a consequence of aquifer overdraft with consequent accentuated land subsidence (vertical soil settlements up to 1.0 m and isokinetic values up to 2.5 cm/year). In the upper plain area, where the aquifer is made up of the apical alluvial fan gravels, directly outcropping on the soil surface, widespread groundwater pollution takes place, mainly determined by direct infiltration of nitrates deriving from farming practices. Particular attention is given also to the methods for the localisation of protection zones around water catchments used for water-supply purposes in relation to the aquifer hydraulic parameters.