Historical reconstruction of erosive storms driving damaging hydrological events in the Bonea basin, Southern Italy

This chapter presents an assessment of annual cumulative erosive storms driving Multiple Damaging Hydrological Events (MDHE) such as floods, landslides and accelerated slope erosion events. This was done in a Mediterranean area where difficulties arise in the reconstruction of the relation between storm erosivity, due to the lack of long detailed and homogeneous recorded time series. This gap has been filled in by merging historical precipitation data from European datasets (Pauling A, Luterbacher J, Casty C, Wanner H, Climate Dynam 26:387–405, 2006) with written proxy documents in which damaging hydrological events were recorded. The research was focused on the Bonea river basin, located in Southern Italy, where a large number of hydrological disasters has occurred (and documented) during the period 1700–2000. For this purpose, a parsimonious approach was used to develop a model named CESAM (Cumulative Erosive Storm Anomalies per Annum) from a previous erosivity anomalies equation and evaluated against erosivity data compatible with the RUSLE scheme. The historical climatology of the Bonea basin has shown pronounced interannual and interdecadal variations dependent on multi-decadal scale erosivity, reflecting the mixed population of thermo-convective and cyclonic rainstorms with large positive-and-high anomalies.