Sviluppo e valutazione di pratiche soglie per separare le piogge erosive responsabili di processi interrill e rill

For the experimental station Masse threshold levels able to separate interrill erosive events from non erosive events were developed and tested. The Masse database was composed of 258 rainy events (189 non-erosive events and 70 interrill erosive events). Thresholds for separating erosive-interrill events from erosive-rill events were developed and verified at Sparacia analysing 77 erosive events (64 interrill and 13 rill). At Masse the threshold in terms of event rainfall depth, Pe, was, among the analyzed variables, the most effective one to distinguish between non-erosive and erosive interrill rainfall events. The rainfall events with a total depth Pe > 13 mm are identified as interrill erosive events. This value is very similar to the 12.7 mm selected by Wischmeier and Smith (1958) that propose a compound criterion (Pe > 12.7 mm or I15 > 6,35 mm in 15 minutes). In our case the compound criterion does not guarantee an improvement in the effectiveness of the single threshold. At Sparacia the threshold I15 > 8,75 mm in 15 min is the most effective, among those analyzed, to select erosive rill events from all erosive events.