Andrea Valentini

Long-term sea level variations can affect specific ocean basins, potentially leading to significant conse-quences for coastal areas, especially where changes in mean sea level are combined with subsidence or negative vertical land motion (VLM). This phenomenon is particularly noticeable along the northern Italian Adriatic coast, which are becoming increasingly vulnerable to flooding. To monitor sea level rise and develop detailed, site-specific adaptation strategies, regional and national institutions manage integrated tide gauge networks. The integration and enhancement of monitoring systems along the Adriatic Sea have been supported by several EU programs, including the Interreg Italy-Croatia AdriaClim project. This has led to the installation of GNSS instruments co-localised with tide gauges, allowing continuous monitoring of the vertical motion of sea level references. Furthermore a levelling activity was carried out in the Emilia-Romagna coastal areas to address the lack in updated vertical reference systems. The vertical reference is crucial for ensuring comparability of data from different stations and for correctly applying forecasting outputs to local conditions. Sea level data from three referenced tide gauge stations were validated and analysed to assess climate change indicators. The mean sea level trend in the northern Adriatic was evaluated using the Seasonal Trend decomposition based on Locally weighted regression smoothing using Loess (STL) method, applied to long-term historical time series from Venezia and Trieste. The Porto Garibaldi time series, however, only became available in 2009, so that a linear regression had to be used to analyse its trend. For comparison, the Venezia and Trieste time series for the same period were also analysed using the linear regression. The main results show site-specific behaviour and emphasise the importance of stable and correctly referenced stations. In fact, it is thanks to the information on VLM computed using the so-called GPS Imaging that we have been able to distinguish between the Relative Sea Level (RSL) component and the Absolute Sea Level (ASL) rise.

Geodetic networks are fundamental for the representation, monitoring, and management of territory. The network of permanent GNSS stations and the tide gauge networks enable the accurate definition and monitoring of the reference system, addressing both spatial and altimetric aspects (with the availability of both ellipsoidal and orthometric heights). Passive networks, used for three-dimensional positioning (via GNSS or traditional topographic instruments) or for altimetric measurements, allow comprehensive access to all parts of the territory and support more localized surveys. The Emilia-Romagna region in Italy is a territory affected by subsidence (both natural and anthropogenic), coastal erosion, landslides, and recent catastrophic events such as earthquakes and extreme weather phenomena. To effectively manage and monitor such a complex territory, relevant authorities have developed an Integrated Geodetic Network project, comprising permanent GNSS stations (capable of providing real-time positioning services), tide gauges, and passive networks referenced to shared coordinate systems. With the support of a geoid undulation model, this system will enable more accurate understanding and management of the territory.

A network of fixed webcam stations has recently been installed along the coast of the Emilia-Romagna region in Italy aiming to enhance the regional Coastal Early Warning System (EWS). The network integrates advanced video monitoring technology to collect and analyze data on coastal dynamics, offering a cost-effective solution to improve storm surge monitoring, shoreline mapping, and coastal management. By deploying eight strategically positioned cameras, the system provides high-resolution spatial and temporal data, enabling real-time monitoring and long-term analyses. This initiative supports civil protection efforts, informed decision-making, and sustainable coastal management while addressing challenges such as environmental monitoring during extreme weather events. The system architecture combines state-of-the-art imaging, processing capabilities, and a web-based visualization platform, adhering to open-source standards and accessibility guidelines. The project exemplifies an innovative, scalable approach to coastal risk assessment and environmental resilience.

State-of-art modelling has shown a largely altered oceanographic environment as a consequence of climate change. The climate models implemented normally present low temporal and spatial resolutions as they aim at a general understanding on how large scale processes vary in a changing climate. Through downscaling projections towards coastal applications it is possible to reach higher resolutions and much more detailed information. If such an approach is performed using unstructured models instead of finite difference ones, it allows for an even better representation of complex morphologies. The latter enables studying more in depth the behavior of coastal environments, such as deltas, that heavily involve the oceanographic and hydrologic components. One of such areas is the Po Delta located in the Northern Adriatic Sea. With its complex system of lagoons and river branches (Maicu et al., 2018), downscaling is fundamental for representing the local processes driven by the interaction between the basin wide circulation and the freshwater inputs. In the context of the European Strategic Italy-Croatia AdriaClim Project (ID 10252001), hydrodynamic downscaling from regional scenario projections to high-resolution coastal applications is undergoing. The final local, high-resolution implementation is a finite element hydrodynamic model that uses the atmospheric forcing, and hydrologic and oceanographic boundaries from the projections.

Within the European Interreg Italy-Croatia project “CoAStal and marine waters integrated monitoring systems for ecosystems proteCtion AnD managemEnt (CASCADE)” ( https://www.italy-croatia.eu/web/cascade), an off-line coupled physical-biogeochemical box-model was implemented in the shallow Goro lagoon (northern Adriatic Sea, Po river delta region) in order to study its biogeochemical dynamics. The lagoon is subject to intensive shellfish (Ruditapes Philippinarum) farming: more than one third of the lagoon surface is exploited for clam farming, with an annual production that reached a maximum of approximately 15,000 t y-1 in the early 1990s.The biogeochemical component of the modelling system is the Biogeochemical Flux Model (BFM), accounting for the biogeochemical cycling processes occurring in water and sediments, including (with a functional groups approach) the planktonic and the zoobenthic biota, and fully resolving the benthic pelagic coupling. BFM is implemented in several areas of the lagoon having homogeneous characteristics and different shellfish farming conditions. The areas resolved by the BFM are connected among each other by the mass exchanges (dissolved and particulate) depending by the water circulation in the lagoon that is modeled by the Shallow Water Hydrodynamic Finite Element Model (SHYFEM).The results of the simulation show that the model is able to capture the essential dynamics of the lagoon, with values almost in the same order of magnitude with the measurements from experimental campaigns runned during the project. Particular attention (trough sensitivity experiments) is given to the impact of the the shellfish farming on the lagoon biogeochemical dynamics. The ultimate goal of this work is to provide stakeholders with useful information regarding the evolving biogeochemical conditions that favor the sustainability of the shellfish farming.

This study examines the wind-wave characteristics along the Emilia-Romagna coasts (northern Adriatic Sea, Italy) with a 10-year wave simulation for the period 2010–2019 performed with the high-resolution unstructured-grid WAVEWATCH III (WW3) coastal wave model. The wave parameters (significant wave height, mean and peak wave period, and wave direction) were validated with the in situ measurements at a coastal station, Cesenatico. In the coastal belt, the annual mean wave heights varied from 0.2–0.4 m, and the seasonal mean was highest for the winter period (>0.4 m). The Emilia-Romagna coastal belt was characterized by wave and spectra seasonal signals with two dominant frequencies of the order of 10 and 5–6 s for autumn and winter and 7–9 and 4 s for spring and summer. The wavelet power spectra of significant wave height for 10 years show considerable variability, having monthly and seasonal periods. This validated and calibrated data set enabled us to study the probability distributions of the significant wave height along the coasts and define a hazard index based on a fitted Weibull probability distribution function.

This paper described the implementation of a forecasting system of the coupled physical and biogeochemical state of the northern Adriatic Sea and discussed the preliminary results. The forecasting system is composed of two components: the NEMO general circulation model and the BFM biogeochemical model. The BFM component includes an explicit benthic pelagic coupling providing fluxes at the sediment–water interface and the dynamic of the major benthic state variables. The system is forced by atmospheric forcing from a limited-area model and by available land-based (river runoff and nutrient load) data. The preliminary results were validated against available remote and in situ observations. The validation effort indicated a good performance of the system in defining the basin scale characteristics, while locally the forecasting model performance seemed mostly impaired by the uncertainties in the definition of the land-based forcing.

This study examines the wind-wave characteristics along the Emilia-Romagna coasts (northern Adriatic Sea, Italy) with a 10-year wave simulation for the period 2010–2019 performed with the high-resolution unstructured-grid WW3 coastal wave model. The wave parameters (significant wave height, mean and peak wave period, and direction) were validated with the in-situ measurements at a coastal station Cesenatico. In the coastal belt, the annual mean wave heights varied from 0.2–0.4 m, and the seasonal mean was highest for the winter period (> 0.4m). The Emilia-Romagna coastal belt was characterized by wave and spectra seasonal signals with two dominant frequencies of the order of 10 s/ 5–6 s for autumn and winter, and 7–9 s/4 s for spring and summer. The wavelet power spectra of significant wave height for 10-years show considerable variability, having monthly and seasonal periods. This validated and calibrated data set enabled us to study the probability distributions of the significant wave height along the coasts and define a hazard index based on a fitted Weibull probability distribution function.

This paper reviews the state of the art in storm surge forecasting and its particular application in the northern Adriatic Sea. The city of Venice already depends on operational storm surge forecasting systems to warn the population and economy of imminent flood threats, as well as help to protect the extensive cultural heritage. This will be more important in the future, with the new mobile barriers called MOSE (MOdulo Sperimentale Elettromeccanico, Experimental Electromechanical Module) that will be completed by 2021. The barriers will depend on accurate storm surge forecasting to control their operation. In this paper, the physics behind the flooding of Venice is discussed, and the state of the art of storm surge forecasting in Europe is reviewed. The challenges for the surge forecasting systems are analyzed, especially in view of uncertainty. This includes consideration of selected historic extreme events that were particularly difficult to forecast. Four potential improvements are identified: (1) improve meteorological forecasts, (2) develop ensemble forecasting, (3) assimilation of water level measurements and (4) develop a multimodel approach.