Valchiavenna: un esempio di cartografia geologico-tecnica

The "Valchiavenna" project involved the carrying out of a set of geotechnical maps (548 sq. km) at the 1:10,000 scale (referred to "CTR" by Lombardy Region), including the Italian part of Mera river drainage basin. The maps are based on original field mapping, have not been drawn from a pre-existing geological cartography and constitute the prototype described below. The geotechnical map overlaps a lithotechnical map, based on 40 lithological non-formal units (respectively, 25 for quaternary deposits and 15 for the bedrock) and a brittle lineaments map, drawn with both field and detailed remote sensing data, focusing on definition of joint net range and typology. This allows the regional scale characterisation of homogeneous rock masses. The semi-quantitative features definition of the latter enables the utilization of geomechanical classifications for engineering projecting. A conceptual model was developed at the same time of field data acquisition, then was built a series of layers into a geographic database (ESRI), whose combination allows elaboration of new thematic maps, targeted at the performance of the applications.