Procedura automatica per la creazione di mappe di potenziale inondazione fluviale

The present work proposes an automatic procedure implemented in the GIS software GRASS to define potentially fluvial inundated areas, known the conformation of the territory surrounding the river by a DTM, and the water surface profile along the river axis calculated for given discharge through an one-dimensional hydraulic model such as HEC-RAS®. The definition of perifluvial areas subject to inundation turns out to be of considerable importance either for emergency management and for planning activity, such as scheduling of works for the reduction of hydraulic risk or town planning finalized to the optimal use of such areas. The implemented procedure has innovating characteristics; even if it remains substantially one-dimensional, it takes into account the two-dimensionality of territory and inundation phenomena, adducing hypotheses that let to correct many errors typical of one-dimensional usually employed procedure. With respect to a two-dimensional model, it has the advantage that it needs a lower computational effort, that allows to apply it to river reaches very long (of the order of 100 km). A first validation of the procedure was performed comparing the historical inundated area and the potentially inundated area caused by the alluvial event in 1994 that interested Tanaro river; in particular, attention was focused on the reach including the Alessandria city, obtaining satisfactory results. The new module, r.inund.fluv, is distributed under the terms of the GNU General Public License, free downloading from the web site http://grass.osgeo.org/wiki/GRASS_AddOns.