Criteria for the elaboration of susceptibility maps for DGSD phenomena in Central Italy

Abstract

In this research we analyze the overall requirement and use of parameters derived from geomorphic techniques for Deep-seated Gravitational Slope Deformation (DGSD) susceptibility assessment in the Central Apennine (Umbria-Marche area - Central Italy). The geometric parameters characterizing the topography affected by DGSD are investigated by remote sensing data. In particular, Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) improved with Landsat ETM+ imageries are used to detect the topography signature representative of DGSD susceptibility. Landsat ETM+ data are processed with Spectral Mixing Analysis (SMA). The topographic DGSD signature is determined by different topographic parameters such as slope, relief, aspect and curvature which can be used as a DGSD index degree. To characterize important physical properties of the aforesaid signature, the linear mixing model between the dark surface endmember and both the substrate and vegetation endmembers was used. That model highlights the extent to which shadowing and non-reflective surfaces, combined with illuminated substrate and vegetation at sub-pixel scale, can modulate spectrally mixed ETM+ reflectances in a ridge topography within the DGSD signature. The final results indicate that when incorporated with optical SMA of the Landsat ETM+, the SRTM analysis should improve the capacity for mapping and identifying DGSD in specific landscapes.