Verso un Sistema Informativo Geologico: l’applicativo CARGeo per la banca dati Geologica della Regione Lombardia

Abstract

In the framework of the national mapping program «CARGNew Italian Geological Map at 1:50.000 scale», Regione Lombardia is generating a detailed map (1:10.000 scale) of its territory. Surveying criteria have been carefully defined in order to produce homogeneous geological maps: geological survey has been performed at the 1:10.000 scale, and data have been stored in a GIS-oriented database. The detailed survey scale improved the geological knowledge: the new maps represent an important tool for territorial planning requirements of public administrations and engineering geologists (e.g. in hydrogeological and seismic risk evaluation). Field geologists performed data input in the geological data base by alternating field campaigns and data input throughout the year, taking advantage of periods when field activities are slackened (i.e. according to climate conditions). In this way, data entry is nearly synchronous with data collection, and field data become quickly accessible. Data entry by the field geologists on one side slows down the field activity, however, it guarantees a precise digitalization of geometric data and a correct attribute assignment, allowing to optimize working time. To allow the data entry to non-GIS-specialized users, we developed an ArcView®-VisualBasic®-MSAccess® application, enabling the simultaneous acquisition of geometric and alphanumeric data. Data base management and cartographic production are performed with ArcInfo®, through specific procedures which, after data reorganization and control (both alphanumeric and geometric), lead to the final cartographic output at different scales. The 1:10.000 geological database is migrated in the ArcSDE structure and prepared for data view, query and download (www.cartografia.regione.lombardia.it/cargweb) using ESRI (ArcIMS) tools. From the 1:10.000 geological database we derived the database for the 1:50.000 CARG maps by both automatic and manual generalization according to the CARG-APAT standards. During the different phases of the project, several problems arose, due to both project organization and data storage system (from data collection in the field to elaboration and digitalization, and, in case, to final publication). – Data collection: the survey activity was divided between «bedrock » and «quaternary» specialists. The double survey provided a high-quality geological description of the territory, but slowed the generation of the data-flow. Based on this experience, the last assigned areas are surveyed by a single geologist, under the supervision of quaternary and bedrock experts. – Users feedback: geologists are normally used to draw their maps on paper; learning how to produce electronic maps can be difficult, and the software tools have to be studied very carefully and present user friendly interfaces. Nevertheless, in our experience, a training period has to be planned, and geologists have to be supported by a GIS expert, who can understand their needs and modify the software accordingly. – System architecture: the ArcView®-VisualBasic®-MSAccess® (Windows platform) – ArcInfo® (UNIX platform) environment, revealed problems in the client-server stability of an earlier version; some unsolved troubles remain, mainly related to the network architecture. The presence in the CARG-Regione Lombardia crew of consultant geologists, experienced and trained in collection, analysis and data entry in the final database, accelerated the critical phases of: – Data base derivation from Regione Lombardia dataset to CARG-APAT standard.