Relative Sea-Level Rise Scenario for 2100 along the Coast of South Eastern Sicily (Italy) by InSAR Data, Satellite Images and High-Resolution Topography

Abstract

The global sea-level rise (SLR) projections for the next few decades are the basis for developing flooding maps that depict the expected hazard scenarios. However, the spatially variable land subsidence has generally not been considered in the current projections. In this study, we use geodetic data from global navigation satellite system (GNSS), synthetic aperture radar interferometric measurements (InSAR) and sea-level data from tidal stations to show the combined effects of land subsidence and SLR along the coast between Catania and Marzamemi, in south-eastern Sicily (southern Italy). This is one of the most active tectonic areas of the Mediterranean basin, which drives accelerated SLR, continuous coastal retreat and increasing effects of flooding and storms surges. We focus on six selected areas, which show valuable coastal infrastructures and natural reserves where the expected SLR in the next few years could be a potential cause of significant land flooding and morphological changes of the coastal strip. Through a multidisciplinary study, the multi-temporal flooding scenarios until 2100, have been estimated. Results are based on the spatially variable rates of vertical land movements (VLM), the topographic features of the area provided by airborne Light Detection And Ranging (LiDAR) data and the Intergovernmental Panel on Climate Change (IPCC) projections of SLR in the Representative Concentration Pathways RCP 2.6 and RCP 8.5 emission scenarios. In addition, from the analysis of the time series of optical satellite images, a coastal retreat up to 70 m has been observed at the Ciane river mouth (Siracusa) in the time span 2001–2019. Our results show a diffuse land subsidence locally exceeding 10 ± 2.5 mm/year in some areas, due to compacting artificial landfill, salt marshes and Holocene soft deposits. Given ongoing land subsidence, a high end of RSLR in the RCP 8.5 at 0.52 ± 0.05 m and 1.52 ± 0.13 m is expected for 2050 AD and 2100 AD, respectively, with an exposed area of about 9.7 km2 that will be vulnerable to inundation in the next 80 years.

Present‐Day Surface Deformation of Sicily Derived From Sentinel‐1 InSAR Time‐Series

“…As discussed in the previous section, we speculate that this short‐term subsidence pattern, also evidenced by Anzidei et al. (2021), could represent a transient deformation related to the interseismic elastic loading of an east‐dipping normal fault system located offshore the Hyblean Plateau, likely along the reactivated Malta Escarpment (e.g., Argnani & Bonazzi, 2005; Gambino et al., 2021). However, InSAR monitoring of interseismic loading phases on active faults is mostly limited to major strike‐slip faults, such as the North Anatolian, the San Andreas, or the Haiyuan faults (e.g., Cavalié et al., 2008; Tong et al., 2013; Wright et al., 2001), where slip rates exceed several tens of mm/yr.…”

Potential Sea Level Rise Inundation in the Mediterranean: From Susceptibility Assessment to Risk Scenarios for Policy Action

“…With regards to the Mediterranean, preliminary studies have been focused on the assessment of the proneness of the alluvial coastal plains to be impacted by future RSLs accounting for future sea level projections coupled with tectonic and glaciohydro-isostatic contributions (e.g., [15][16][17][18][19][20][21]). Several coastal studies have also considered the local contribution of vertical ground movements by assessing displacement rates from satellite data [22][23][24][25][26][27] and Global Navigation Satellite System (GNSS) stations [28]. These studies highlight the fact that wide areas of the Mediterranean are considered particularly prone to be affected by shoreline retreat and permanent submersion processes by the end of the century as a consequence of RSL increase.…”

Using CYGNSS Data to Map Flood Inundation during the 2021 Extreme Precipitation in Henan Province, China

“…In fact, in addition to being used for flood monitoring, CYGNSS technology has also shown great potential in monitoring global climate change in recent years. For example, CYGNSS has been used for monitoring wetland area change [52], coastal flooding [53], and sea level rise [54]. These applications can help researchers better understand the framework of climate change, and can also be used as a reference when relevant departments formulate corresponding climate policies [55].…”