Delineation of customized terrain units for geo - hydrological susceptibility analysis at large scale

Geo – hydrological events are characterized by different scale and morphologic conditioning parameters, for this reason the susceptibility analysis of landslides and flood events require a multi – scale study and appropriate terrain unit according to their physiographic context. To improve the delineation of appropriate terrain units for the mentioned before phenomena, the study will be focused on the identification of geomorphological domains such as hillslope, unchanneled, channeled and fluvial, within landslides and flooding could occur. The workflow consists of the implementation of a variant of the ‘’Slope – Area’’ function and the use of few input parameters: slope, curvature and hydrological data; into the software GIS ArcMpas and the programming software MATLAB. In detail, the new function represents the relationship between Slope, Planar Curvature, Profile Curvature and weighted drainage area, by runoff value derived from the Hydrological GIS – Based Model ‘’BIGBANG’’. The use of curvature lets a better recognition of the surface morphology variation in term of convexity, concavity, divergency and convergency. The implementation of runoff values permits the calculation of the drainage area as a discharge, allowing in such a way the extraction of the stream network considering the real water supply. In this way, it will be possible to reclassify the territory into hillslopes, unchanneled, channeled and fluvial domains, starting from it will be possible to find out the appropriate terrain unit for landslides and flood events.