Detailed rock failure susceptibility mapping in steep rocky coasts by means of non-contact geostructural surveys: the case study of the Tigullio Gulf (Eastern Liguria, Northern Italy)

Abstract

Abstract. In this study, an engineering geological analysis for the assessment of the rock failure susceptibility of a high, steep, rocky coast was developed by means of non-contact geostructural surveys. The methodology was applied to a 6-km coastal cliff located in the Gulf of Tigullio (Northern Tyrrhenian Sea) between Rapallo and Chiavari.The method is based on the geostructural characterisation of outcropping rock masses through meso-and macroscale stereoscopic analyses of digital photos that were taken continuously from a known distance from the coastline. The results of the method were verified through direct surveys of accessible sample areas. The rock failure susceptibility of the coastal sector was assessed by analysing the fundamental rock slope mechanisms of instability and the results were implemented into a Geographic Information System (GIS).The proposed method is useful for rock failure susceptibility assessments in high, steep, rocky coastal areas, where accessibility is limited due to cliffs or steep slopes. Moreover, the method can be applied to private properties or any other area where a complete and systematic analysis of rock mass structural features cannot be achieved.Compared to direct surveys and to other non-contact methods based on digital terrestrial photogrammetry, the proposed procedure provided good quality data of the structural features of the rock mass at a low cost. Therefore, the method could be applied to similar coastal areas with a high risk of rock failure occurrence.

Relationships between geo-hydrological processes induced by heavy rainfall and land-use: the case of 25 October 2011 in the Vernazza catchment (Cinque Terre, NW Italy)

“…Landslides are a peculiarity of the coast of Liguria (Brandolini et al, 2007;Carobene & Cevasco, 2011;Cevasco et al, 2000;De Vita et al, 2012;Terranova, 1984) but within the Vernazza catchment, due to its morphological features, shallow landslides triggered by rainfall are prevalent (Cevasco et al, 2013). …”

Storminess and geo-hydrological events affecting small coastal basins in a terraced Mediterranean environment

“…However, coastal environments with mountain-like geomorphological features can also be seriously exposed to accelerated erosion and landslide and flood risks (Guthrie and Evans, 2004;Cevasco et al, 2010;Santo et al, 2012). In such a case, risk conditions are increased by both the high economic value of coastal areas and the large number of tourists that visit these areas (Guadagno et al, 2005;De Vita et al, 2012;McCullough et al, 2013;Revellino et al, 2013;Martino and Mazzanti, 2014).…”

Remote sensing techniques applied to geomorphological mapping of rocky coast: the case study of Gallinara Island (Western Liguria, Italy)

“…The resulting DTMs, derived by the integration of multibeam and laser scanner point clouds, allowed to obtain significative geological and geomorphological information useful for the evaluation of rocky cliffs conditions and for mapping rock-failure susceptibility (De Vita et al, 2012).…”

“…Laser scanner and multibeam integration is widely applied to support geo-hydrological risk mitigation measures assessment and land management in coastal or fluvial areas (Alho et al, 2009;Aguilar et al, 2017;Boeder, Kersten, Hesse, Thies, & Sauer, 2010Brandolini, Faccini, Robbiano, & Terranova, 2009;Capra et al, 2017;Colbo, Ross, Brown, & Weber, 2014;Del Monte et al, 2015;Ferrari et al, 2019;Mancini et al, 2013;Mills, Buckley, Mitchell, Clarke, & Edwards, 2005;Monteys, Harris, Caloca, & Cahalane, 2015;Pranzini & Williams, 2013;Raso, Brandolini, Faccini, & Firpo, 2016;Raso et al, 2017;Troisi, Del Pizzo, Gaglione, Miccio, & Testa, 2015). Investigations on the stability of rocky coasts have often been carried out using such remote sensing techniques (Naylor, Stephenson, & Trenhaile, 2010), both for monitoring erosion of hard rock coastal cliffs (Rosser, Petley, Lim, Dunning, & Allison, 2005), and for detailed mapping of rock-failure susceptibility by means of non-contact geostructural surveys (De Vita, Cevasco, & Cavallo, 2012). In fact, in the framework of rocky coastal environment, where it is necessary to get detailed georeferenced data both at sea and inland, remote sensing techniques allow the acquisition of the whole information in a single and integrated survey campaign.…”