Ecosystem services at risk in Italy from coastal inundation under extreme sea level scenarios up to 2050: A spatially resolved approach supporting climate change adaptation.

According to the latest projections of the Intergovernmental Panel on Climate Change, at the end of the century, coastal zones and low-lying ecosystems will be increasingly threatened by rising global mean sea levels. In order to support integrated coastal zone management and advance the basic "source-pathway-receptor-consequence" approach focused on traditional receptors (e.g., population, infrastructure, and economy), a novel risk framework is proposed able to evaluate potential risks of loss or degradation of ecosystem services (ESs) due to projected extreme sea level scenarios in the Italian coast. Three risk scenarios for the reference period (1969-2010) and future time frame up to 2050 under RCP4.5 and RCP8.5 are developed by integrating extreme water-level projections related to changing climate conditions, with vulnerability information about the topography, distance from coastlines, and presence of artificial protections. A risk assessment is then performed considering the potential effects of the spatial-temporal variability of inundations and land use on the supply level and spatial distribution of ESs. The results of the analysis are summarized into a spatially explicit risk index, useful to rank coastal areas more prone to ESs losses or degradation due to coastal inundation at the national scale. Overall, the Northern Adriatic coast is scored at high risk of ESs loss or degradation in the future scenario. Other small coastal strips with medium risk scores are the Eastern Puglia coast, Western Sardinia, and Tuscany's coast. The ESs Coastal Risk Index provides an easy-to-understand screening assessment that could support the prioritization of areas for coastal adaptation at the national scale. Moreover, this index allows the direct evaluation of the public value of ecosystems and supports more effective territorial planning and environmental management decisions. In particular, it could support the mainstreaming of ecosystem-based approaches (e.g., ecological engineering and green infrastructures) to mitigate the risks of climate change and extreme events while protecting ecosystems and biodiversity. Integr Environ Assess Manag 2022;18:1564-1577. © 2021 SETAC.

Tidal inlet seafloor changes induced by recently built hard structures.

Tidal inlets are extremely dynamic environments that are often strongly modified by anthropogenic intervention. In this study, we describe the rapid evolution of a highly human-impacted tidal inlet, studied through repeated high-resolution multibeam surveys and geomorphometric analysis. We document the rapid change induced by new hard coastal structures built to protect the historical city of Venice (Italy). A new breakwater erected between 2011 and 2013 induced the formation of large scour holes with the consequent erosion of about 170 · 103 ± 15.6% m3 of sediment until 2016. The construction of a new island in the middle of the inlet and the restriction of the inlet channel caused a general change of the inlet sedimentary regime from depositional to erosive with a net sediment loss of about 612 · 103 ± 42.7% m3, a reduction of the dune field area by more than 50% in about five years, and a coarsening in the sediment distribution. Our results give new insight on the tidal inlet resilience to changes, distinguishing two different phases in its recent evolution: (i) a very rapid response (from 2011 to 2013) of the seafloor morphology with scour-hole erosion at the new breakwater tips at a rate of about 45⋅103 m3/year and the disappearing of dune fields at a rate of 104⋅103 m2/year; and (ii) a general slowdown of the erosive processes from 2013 to 2016. Nevertheless, the erosion continues at the breakwater, though at a reduced rate, possibly representing a threat to the hard structure. In view of global mean sea level rise and consequent proliferation of hard structures along the coast all over the world, the combined use of very high resolution multibeam surveys and repeatable geomorphometric analysis proposed in this study will be crucial for the monitoring and future management of coastal environments.

Selecting sustainable alternatives for cruise ships in Venice using multi-criteria decision analysis.

The rapid growth of cruise ship tourism increases the use of historic port cities as strategic hubs for cruise ship operators. Benefits derived from increased tourism for the municipality and cruise ships are often at odds with the environmental and social impacts associated with continued historical port use. This study illustrates the use of Multi-Criteria Decision Analysis (MCDA) for weighing of various criteria and metrics related to the environment, economy, and social sustainability for the selection of a sustainable cruise line route. Specifically, MCDA methodology was employed in Venice, Italy to illustrate its application. First, the four most representative navigational route projects among those presented to local authorities were assessed based on social, economic, and environmental considerations. Second, a pool of experts representing the local authority, private port businesses, and cruise line industry were consulted to evaluate the validity and weight assignments for the selected criteria. Finally, a sensitivity analysis was employed to assess the robustness of the recommendations using an evaluation of weight changes and their effects on the ranking of alternative navigational routes. The results were presented and discussed in a multi-stakeholder meeting to further the route selection process.

High resolution multibeam and hydrodynamic datasets of tidal channels and inlets of the Venice Lagoon.

Tidal channels are crucial for the functioning of wetlands, though their morphological properties, which are relevant for seafloor habitats and flow, have been understudied so far. Here, we release a dataset composed of Digital Terrain Models (DTMs) extracted from a total of 2,500 linear kilometres of high-resolution multibeam echosounder (MBES) data collected in 2013 covering the entire network of tidal channels and inlets of the Venice Lagoon, Italy. The dataset comprises also the backscatter (BS) data, which reflect the acoustic properties of the seafloor, and the tidal current fields simulated by means of a high-resolution three-dimensional unstructured hydrodynamic model. The DTMs and the current fields help define how morphological and benthic properties of tidal channels are affected by the action of currents. These data are of potential broad interest not only to geomorphologists, oceanographers and ecologists studying the morphology, hydrodynamics, sediment transport and benthic habitats of tidal environments, but also to coastal engineers and stakeholders for cost-effective monitoring and sustainable management of this peculiar shallow coastal system.