Comparison of 2d models for the simulation of the october 1954 debris flow and flood event at maiori (campania region, italy)

Abstract

The Campania Region (southern Italy) is characterized by a frequent occurrence of volcaniclastic debris flows causing extreme loss of life and property damage where a large population occupies alluvial fans. In 1954 the small town of Maiori was struck by several debris flows initiated as soil slips triggered by prolonged rainfalls. Historical sources report seaward shift of the coastline of some tens of metres during major food events, also documented by air photographs taken soon after the disaster. The 1954 event has been simulated using two commercially available models, DAN-W and FLO-2D. DAN-W is a program used to model the post-failure motion of rapid landslides such as debris flows and suitable for estimating their runout behaviour. The same 1954 event has been further simulated by means of FLO- 2D, whose sensitivity to different routing conditions was tested by varying several critical input data as the shape of flow hydrograph and the volume mobilised. The rheological parameters of the model have been assigned assuming a Bingham behaviour for the debris flow, based on other works available in literature. The results obtained with both programs have been then critically commented, with the aim of assessing their capability to reproduce the studied event and, more generally, to help in the specific hazard zoning and mapping.