The internal structure of erosive and non-erosive storm events for interpretation of erosive processes and rainfall simulation

- A methodology for representing the internal structure of erosive rainfall.
- Compound criteria for sampling erosive storms among the rainfall events.
- Statistics of the inter-storm properties of erosive rainfalls.
- Simulation of the rainfall profiles of natural erosive storms.

SummaryThe paper presents an analysis of the rainfall structure for 228 events defined using a minimum interevent time MIT = 6 h recorded in the experimental station of Masse (Central Italy). The events were further sub-sampled to define a set of storms, these being events in which at least one 5 min interval had a rainfall rate of at least 9.6 mm/h. Some storms were erosive and some non-erosive respectively if the corresponding runoff volume and soil loss measured at Masse were greater than zero or not. The selected rain rate threshold is not able, alone, to sample all and only the erosive events recorded at Masse. The properties of the storms were further analyzed in terms of the properties of blocks (or runs) of 5 min periods that had rain above the nominated threshold rainfall rate and of the corresponding antecedent and subsequent rainfall. The goal was to develop ways of representing the time distribution of rainfall that might have explanatory power in terms of soil loss and that might be useful to select compound criterion (overall and profile characteristics) for the identification of erosive events from pluviograph records and to simulate rainfall corresponding with those of natural erosive events in Central Italy. Some statistical erosive storm hyetographs have been simulated according to the results of the analysis.