LUPIA PALMIERI E., CICCACCI S., CIVITELLI G., CORDA L., D’ALESSANDRO L., DEL MONTE M., FREDI P. & PUGLIESE F.
Geomorfologia quantitativa e morfodinamica: I – Il bacino idrografico del Fiume Sinello – Quantitative geomorphology and morphodinamics of the Abruzzo, Italy: I – The drainage basin of the River Sinello
Pages 31-46
Abstract
This paper covers a part of an extensive research on the geology and geomorphology of Abruzzo, the aim of which is to underline the role of quantitative geomorphic analysis in the individualization of areas with fast morphological evolution. In this frame the most significant results obtained for the River Sinello drainage basin are here shown. This basin, in the southernmost part of this region, is emplaced in a lithologically variable and structurally complex area which includes the eastern border of the Apennines and the southern Adriatic foredeep corresponding to the «Molise sedimentary basin». Information drawn during researches allowed to define in a satisfactory way the morpho-structural assessment and the typology as well as the intensity of denudation processes. The morphological pattern of the basin seems to be controlled by some tectonic directions, among which N-S, E-W, NESW, and NW-SE are especially outstanding. The azimuthal distribution of each stream order, defined after Strahler, allowed to outline the possible course of activity relevant to the mentioned tectonic lines. The NW-SE, NE-SW and E-W directions seem to have acted in the most ancient time; the latter, however is likely to have been reactivated, as it clearly controls, together with the N-S trending tectonic fine, the very recent evolution of the drainage network. The basin can be divided into three sectors, each one characterized by sufficiently unitary geological conditions. Over two thirds of the basin surface is affected by intense morphogenetic processes. These processes are particularly evident and widespread in the mountain sector, also due to strong tectonization. Particularly active is denudation on slopes, mainly consisting of landslides, often of remarkable size. The distribution and intensity of denudation in the mountain sector are in accordance with the drainage network disorganization and rather high values of «erosion index». Although less marked and widespread, landslides are the main denudation process also in the basin middle sector and information drawn from Quantitative Geomorphology are in accordance again. The lower sector is characterised by low relief amplitude and reduced intensity of slope processes and stream deepening. The hypsometric analysis made it possible to define accurately the areas which are affected by intense morphogenetic processes. Markedly downward concave curves show that fluvial deepening is the dominant processes in the partial basins of the Sinello headwater. Down valley, both in the mountain and in the middle sector, the hypsometric curves evidence that the morphogenetic activity is still marked but in this case fluvial deepening is balanced by gravity processes on slopes. Parallely, badlands become more widespread as it is shown by upward concave hypsometric curves.