Abstract
In the present work, preliminary results are reported from an ongoing research study aimed at developing an improved prediction model to estimate the sediment yield in Italian ungauged river basins. The statistical correlations between a set of hydro-geomorphometric parameters and suspended sediment yield (SSY) data from 30 Italian rivers were investigated. The main question is whether such variables are helpful to explain the behavior of fluvial systems in the sediment delivery process. To this aim, a broad set of variables, simply derived from digital cartographic sources and available data records, was utilized in order to take into account all the possible features and processes having some influence on sediment production and conveyance. A stepwise regression analysis pointed out that, among all possibilities, the catchment elevation range (Hr), the density of stream hierarchical anomaly (Da), and the stream channel slope ratio (ΔSs) are significantly linked to the SSY. The derived linear regression model equation was proven to be satisfactory (r2-adjusted = 0.72; F-significance = 5.7 × 10−8; ME = 0.61), however, the percentage standard error (40%) implies that the model is still affected by some uncertainties. These can be justified, on one hand, by the wide variance and, on the other hand, by the quality of the observed SSY data. Reducing these uncertainties will be the effort in the follow-up of the research.
Highlights
The assessment of river sediment yield (SY) is a focal issue in geomorphological research
A stepwise linear regression between the dependent and the independent variables from the whole sample of 30 catchments was carried out for selecting the most significant variables to enter in the prediction model
The stepwise procedure was stopped at the third predictor, since it was observed that further inputs would not have significantly improved the model performance while reducing, at the same time, the model significance
Summary
The assessment of river sediment yield (SY) is a focal issue in geomorphological research. Theoretical models are needed to fill this gap. This topic has been addressed by many authors who proposed different solutions for sediment yield prediction, from simple parametric equations to refined physically-based models. These latter are commonly utilized by hydraulic engineers mainly for design purposes. An important limit of such models is that they are heavily data-requiring and time-consuming, so they are generally suitable for fields and small catchments
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