Effectiveness and applicability of flood barriers for risk mitigation in flash-flood prone Mediterranean area

Dipartimento di Ingegneria, Università di Messina Contrada di Dio, Villaggio S. Agata, 98166, Messina, Italy

^a Corresponding author: drappazzo@unime.it

Abstract

The new policy of flood risk management is to give more attention to non-structural measures, allowing people to “live with floods” rather than “fight floods”. To protect existing buildings there are two main mitigation strategies: dry proofing and wet proofing. One measure of dry proofing is the shielding, consisting in the use of flood barriers, which can be installed at the entrance of the buildings or at a certain distance from them (including the placing along the banks or crossing a street). These flood protection structures are easier and faster to install rather than sandbags. This paper shows the results applied to a case study in the city of Barcellona, Sicily, Italy that is crossed by a river and suffered a severe inundation in November 2011. To study the effectiveness of using these flood barriers, a 2D hydrodynamic model has been used: the barriers has been placed along a road to inhibit the flow from flooding the protected area. While in North Europe these types of barriers are commonly used, because those areas are typically interested in clear water floods, in Italy flash floods and mud-debris-flows are more frequent and limit their use. The purpose of this work is to verify if these types of barriers are effective when placed along Mediterranean river courses and, especially, to be sure about their stability while subjected to the hydrodynamic effects of these kind of events. To gain this aim, the computed stresses from the modelling have been compared with the stability values of the barriers provided by the producers, evaluating barriers’ stability against overturning and sliding. Simulations show how the flood barriers can mitigate the hydraulic risk, being able to withstand the hydrodynamic pressures and managing to divert the flow of water, thus avoiding that the flood water hits very exposed areas.