The Use of Remote Sensed Data and GIS to Produce a Digital Geomorphological Map of a Test Area in Central Italy.

Thematic maps in the Earth Sciences are an essential tool for the representation, analysis and visualization of geological processes. Among the large variety of thematic maps, geomorphological maps are particularly useful in understanding natural phenomena associated with human activities (Dramis & Bisci, 1998 and references within). Geomorphological maps report the erosion and depositional relief landforms, including submarine ones, highlighting the morphographic and morphometric characters and interpreting the endogenous and exogenous morphological processes, both past or present, that produce and shape the topographic relief. In this kind of maps, the chronological sequence is also reported, distinguishing between active and inactive landforms. The geomorphological mapping, in addition to its scientific value, is the necessary starting point of different studies such applied geology and environmental protection investigations for socio-economic improvement. A major problem with geomorphological information is that it is extremely complex to be represented due to the huge amount of data. In particular, the reproduced information can be summarized as follows: - Topographic, hydrographical and morphometric data; - Lithological and structural data; - Morphogenetic processes: - Structural and volcanic landforms, - Mass wasting landforms, - Karst landforms, - Eolic landforms, - Glacial and nival landforms, - Marine (emerged and submerged), lagoon and lacustrine landforms, - Large relict and flattened areas with minor forms of complex origin associated, - Weathering landforms, - Anthropic landforms. - Morpho-chronologic data; - Morpho-evolutive data. Often the result is an analogical map that is not easily readable, both for the large amount of information, or for the great number of symbols associated with the different landforms. In order to adapt this kind of data to a digital file, the original map must be converted in a vector format (points, poly-lines and polygons) using a Geographical Information System or GIS software (Bocco et al., 2001; Gustavsson et al., 2006; Vitek et al., 1996). The use of the rich symbolism available in most GIS software, improve the graphic rendering, but does not solve the problem of readability of the map. Images acquired by remote sensing and image analysis techniques can bring a significant contribution in improving the geomorphological mapping. The main results of this approach are: - a static and dynamic visualization (3D visualization) of Digital Elevation Models (DEMs) derived from satellite data. These techniques allow a better view of shapes and morphogenetic processes represented in the map. - the calculation of primary and secondary topographic attributes (slope, aspect, planar and radial curvature, roughness) closely related to the presence of some morphogenetic processes and their level of activity. The selection of meaningful ranges of attribute values enable to identify the geometry of the landforms. - an analysis of multispectral images, with various combinations of RGB bands to highlight some specific morphogenetic processes (such as landslide prone areas). In this paper the geomorphological map of the Subasio Mountain Regional Park (Umbria region, central Italy) is presented. The map is the result of the interaction of different datasets, both traditional and innovative in geomorphology. Aerial photos and field survey are enhanced by DEMs and satellite images to achieve a digital final product that is not only a simple thematic map, but also an interactive and upgradable Geographical Database. The geomorphological processes producing the present landscape are therefore better visible and understandable through the use of new tools: hillshade layer in transparency under different thematic maps and 3D virtual flight on the area where the map is overlaid to satellite images in a new, prospective view.