The Impact of Future Sea-Level Rise on Low-Lying Subsiding Coasts: A Case Study of Tavoliere Delle Puglie (Southern Italy)

Abstract

Low-lying coastal zones are highly subject to coastal hazards as a result of sea-level rise enhanced by natural or anthropogenic land subsidence. A combined analysis using sea-level data and remote sensing techniques allows the estimation of the current rates of land subsidence and shoreline retreat, supporting the development of quantified relative sea-level projections and flood maps, which are appropriate for specific areas. This study focuses on the coastal plain of Tavoliere delle Puglie (Apulia, Southern Italy), facing the Adriatic Sea. In this area, land subsidence is mainly caused by long-term tectonic movements and sediment compaction driven by high anthropogenic pressure, such as groundwater exploitation and constructions of buildings. To assess the expected effects of relative sea-level rise for the next decades, we considered the following multidisciplinary source data: (i) sea-level-rise projections for different climatic scenarios, as reported in the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, (ii) coastal topography from airborne and terrestrial LiDAR data, (iii) Vertical Land Movement (VLM) from the analysis of InSAR and GNSS data, and (iv) shoreline changes obtained from the analysis of orthophotos, historic maps, and satellite images. To assess the expected evolution of the coastal belt, the topographic data were corrected for VLM values, assuming that the rates of land subsidence will remain constant up to 2150. The sea-level-rise projections and expected flooded areas were estimated for the Shared Socioeconomic Pathways SSP1-2.6 and SSP5-8.5, corresponding to low and high greenhouse-gas concentrations, respectively. From our analysis, we estimate that in 2050, 2100, and 2150, up to 50.5 km2, 118.7 km2 and 147.7 km2 of the coast could be submerged, respectively, while beaches could retreat at rates of up to 5.8 m/yr. In this area, sea-level rise will be accelerated by natural and anthropogenic land subsidence at rates of up to −7.5 ± 1.7 mm/yr. Local infrastructure and residential areas are thus highly exposed to an increasing risk of severe inundation by storm surges and sea-level rise in the next decades.

Relative Sea-Level Rise Projections and Flooding Scenarios for 2150 CE for the Island of Ustica (Southern Tyrrhenian Sea, Italy)

“…Our results detail previous regional [18] and local [19][20][21][22][23][24][25][26] scenarios regarding RSLR along the coasts of the Mediterranean. In Section 4, we further discuss the main features of the three investigated coastal tracts and the related expected multitemporal flooding scenarios.…”

An Integrated Approach between Multispectral Satellite Images and Geophysical and Morpho-Topographic Surveys for the Detection of Water Stress Associated with Coastal Dune Erosion

“…The height of the groundwater table is an important aspect that strongly influences vegetative health [9,15,[70][71][72]. Many coastal management authorities are currently considering the use of dune vegetation as an ecosustainable means of protecting coastlines against erosional processes triggered by climate change [55,[73][74][75][76][77].…”

Bayesian Network Analysis for Shoreline Dynamics, Coastal Water Quality, and Their Related Risks in the Venice Littoral Zone, Italy

“…The subsidence in the North Adriatic region results from both natural (e.g., tectonics, glacio-isostasy, and compaction of alluvial finematerial deposits) and anthropogenic factors, notably groundwater extraction, acting at different time scales [49,50]. Combining both subsidence and the impacts of climate change, the relative sea level rise has been increasing in this region at a rate of 1.2 mm.year −1 for the timeframe 1872-2019 [46,51], and this is expected to keep rising in the future [18,47,52] Given these compounding stressors, the case study area is projected to suffer an increased risk of flooding and shoreline retreatment [53], losses, and potential alterations to barrier islands like Lido and Pellestrina, thus exacerbating flood threats to Venice's historic center and its surrounding lagoon [54]. Several solutions have been implemented to cope with these problems, such as beach nourishment in Pellestrina and Cavallino-Treporti, rubble-mound seawalls, and submerged breakwater along the coast [55].…”