A spatially distributed analysis of erosion susceptibility and sediment yield in a river basin by means of geomorphic parameters and regression relationships

Papers published in Hydrology and Earth System Sciences Discussions are under open-access review for the journal Hydrology and Earth System Sciences Abstract In the present work, an application of statistical regression relationships utilising ge-omorphic parameters is attempted in a spatially distributed mode, in order to predict the amount of river sediment supply at varying sections of the drainage network. Simple and multiple regression relationships utilising drainage density D d and hierarchical 5 anomaly index ∆ a as independent variables were applied to the Calvano watershed (Central Italy) at different degree of subdivision in tributary drainage basins, so as to assess their contribution to the whole watershed sediment yield balance. In the same way, the role of small hill-reservoirs as sediment-trap and that of areas affected by bad-lands and of tributary basins exposure were also investigated. Results were tested 10 on the basis of sedimentation estimates from selected reservoirs. The relationships provided a yearly specific sediment yield (SSY) value for the Calvano stream which is according to the average observed SSY in river basins of central Italy flowing to the Adriatic Sea. The use of simple statistical relationships, such as those here adopted, can allow 15 to recognise the sections along the main stream which are more critical in terms of sediment accumulation, which, on turn, can cause sudden water discharge increments and dangerous floods. This approach can provide a tool enabling to locate the hydraulic risk and to point out the areas where soil conservation practices or hydraulic works, such as periodic maintenance of riverbeds, are needed in order to reduce soil erosion 20 and sediment accumulation.