TESTING A DISTRIBUTED APPROACH FOR MODELING SEDIMENT DELIVERY

Both the theoretical basis of a distributed approach to sediment deliv ery and its agreement with basin sediment yield measurements are teste d. At first, by using morphological data of five Apulian and four Cala brian basins, the applicability of a theoretically-based relationship for evaluating the sediment delivery ratio of each morphological unit SDRi, into which a basin is divided, is verified. Using the morphologi cal data of the nine investigated basins, the sediment delivery relati onship, i.e. the relationship of the basin sediment delivery ratio SDR W, and SDRi, is tested. The analysis showed that the relationships, pr oposed by Ferro (1997), establishing the dependence of the a coefficie nt of the sediment delivery relationship on the median travel time and on a drainage density index are yet applicable. The influence of the scale of the basin topographic map on the sediment delivery distribute d approach is also studied. The analysis showed that the ratio between the a coefficient and the median travel time is scale-invariable whil e the link between the coefficient a and the drainage density index ha s to be re-calibrated because the drainage density index is dependent on the map scale used. Finally, the predictive capability of the sedim ent delivery distributed model is validated using the sediment yield m easurements carried out in three small Calabrian basins and in the Apu lian Triolo basin. The analysis showed that the model accuracy is depe ndent on the temporal scale used and the model reliability increases f rom the event to the annual scale.