Geology, soil and seismic risk

The geological cartography of the Emilia-Romagna Plain

The geological map 1:50,000

Most human activities, whether industrial or agricultural, are concentrated in the alluvial plains, and thus a geological surveying project in this area must supply answers to the huge difficulties of territorial management and planning.

The main problem is the use of water resources and their protection against pollution.
Another extremely important factor is the development and management of the large urban areas, which are almost all in the alluvial plains.

Precise three-dimensional stratigraphic knowledge of the sedimentary bodies which make up the underground formations in the plain is essential for any approach to the problems outlined above.

The purpose of the "Geological Map to 1:50,000 of the Emilia-Romagna Po Plain" is to acquire increased knowledge of the alluvial sedimentary bodies which make up the underground formations of the area and represent them in cartography.

The quality of the data and the knowledge available is in reverse proportion to the depth of the bodies investigated; it is possible to describe the first tens of metres of the underground structures in great detail, but the project actually sets out to describe the entire thickness of the alluvial deposits (a few hundred metres).

As part of the work done for the new Geological Map of Italy to scale 1:50,000, the Geological Office of the Emilia-Romagna Region has been carrying out experiments regarding the geological surveying and cartographic representation of the plain areas for about two years, by preparing a prototype in a sector of the Po Plain close to Bologna. For the time being this experiment is unique in Italy and is one of only a few projects of its type world-wide.

The prototype geological map of the Bologna plain is being prepared through a number of working phases.

The first step is the collection of the geological survey data already available from public authorities or private organisations, and the preparation of a database.

The field phases involve the geological surveying of the alluvial deposits which outcrop both in the plain and in the Apennines (terraced alluvial deposits). The surveying of the alluvial deposits within the mountain valleys is essential for an understanding of the relationships between the raising of the chain, subsidence and sedimentation in the plain. This is extremely important for purposes of hydrogeology, seismo-tectonics and research.

The data available are then analysed and organised, and a preliminary model of the geometry of the underground formations is prepared.

This allows the planning of new investigations of the underground formations (continuous cored bore-holes, penetrometric tests, and high resolution seismic analysis) and laboratory tests (C14 dating, pollen analyses to establish the palaeoclimates, geotechnical tests and petrographic analyses) in order to verify the model proposed.

The data acquired will also allow more reliable correlation of the underground sedimentary bodies with the terraced deposits found in the Apennine valleys. At this point, the definitive map can be prepared.

The problem of the representation of the geology of plains and the data relating to the relative underground formations has been tacked by the geological services of Denmark, New Zealand, Canada, Holland and Lower Saxony. Although they are based on similar surveying and data acquisition methods, the cartographic representation techniques proposed by these geological services vary widely, and there is still no standard method of representation.

In the current phase, the cartography proposed by the Emilia-Romagna regional Geological Office emphasises the need to prepare not one geological map but a number of cartographic documents for the same area. These maps differ both in the stratigraphic level investigated (surface map and maps relating to various underground levels) and in the type of information supplied (lithostratigraphy, morphology, hydrogeology, sequential stratigraphy).

The geological database, which will be supplied together with the various cartographies, is extremely important. The database is the information base of the cartography, and makes new interpretations and documents possible

Maps and data of the alluvial plane


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last modified 2024-06-24T11:45:59+02:00
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