Rockfall and debris flow hazard assessment of the coastal road of Gipuzkoa (Northern Spain)

Abstract

The coastal roads of the Gipuzkoa province, Basque Country, Northern Spain, suffer frequent damage and blockage as a consequence of the instability of slopes. In 2006 the Gipuzkoa Road Conservation Service promoted a study aiming at identifying the locations showing the highest risk and prioritizing actions for road stabilization and protection. In this communication the results obtained with the Rockfall Hazard Rating System (RHRS) modified by Budetta (Nat Hazards Earth Syst Sci. Euro Geosci Union, 4:71-81, 2004), which has been adapted to the specificities of the study road, are presented. First, the index has been normalized by the length of the sections analyzed to allow their comparison. Second, rockfall volume and frequency have been modified to accommodate local conditions of the cut-slopes and their hazard level. Finally, the RHRS has been adapted to account for the occurrence of small-size debris flow events. © Springer-Verlag Berlin Heidelberg 2013.