Geomorphological quantitative analysis of High Tiber Valley drainage network (Umbria, Italy).

Quantitative Geomorphology is one of the most innovative and promising methods in landscape evolution research. In active tectonic areas, the creation and evolution of topography can be controlled by active fault segments and measured by means of morphometric indexes that mark the topographic surface response to tectonic impulses. A natural geomorphological system aims to an equilibrium condition where the energy necessary to erode, transport and sediment is minimized. This ideal state results in a typical and well defined geometry. Measuring how and where topography differs from this ideal model allows to understand the tectonic control on morphology. To achieve this goal a reliable digital topographic model must be used. Currently Digital Elevation Models (DEMs) are the most used topographic databases and Geographical Information Systems represent the most appropriate tools to analyze this kind of data. In this work we propose the results of some quantitative geomorphological analyses of High Tiber Valley Quaternary basin as a complementary technique to determine the spatial variations of disequilibrium due to tectonic impulses. Moreover we compare two kinds of DEMs frequently used in these studies to highlight differences and potentialities.