Search

This contribution presents the effectiveness and the potentialities of a consolidated technique—the video-cluster analysis—to the study of turbulent flow and breaking waves, in order to demonstrate its suitability as a low-cost, non-intrusive method to derive quantitative key parameters describing the wave–structure interaction processes at coastal defense structures. For this purpose, a new methodology, consisting of a series of pre- and post-processing techniques developed to optimize the automatic detection of clusters in video imagery, was designed to process the video-records of experiments of wave run-up and wave overtopping at sea-dikes subjected to irregular waves. The results of the cluster analysis were elaborated to reconstruct the instantaneous profiles of the free-surface elevations across the structure crest and derive simultaneous information on overtopping volumes, discharges, depths, and velocities and to get spatial-time maps of the concentration of the air entrapped in the liquid phase. The accuracy of the methodology is demonstrated by comparing the quantities derived from the cluster analysis to laboratory measurements performed with resistive gauges and acoustic Doppler profilers. The novelty of the work is either represented by the results of the application of the cluster-analysis and by the procedures of optimizations, whose ensemble may establish a best practice and represent a guideline for other applications.

A three degrees-of-freedom model based on the potential flow theory was implemented to represent the motion of a slender cylindrical buoy under waves. The model calibration was performed by means of the comparison between the model results and the experiments performed at the Laboratory of Hydraulic Engineering of the University of Bologna (Italy). The dynamics of the floating cylinder, placed at the mid-section of the wave flume and anchored at the bottom through a mooring system of four catenaries, were obtained through videography analysis, providing surge, heave and pitch motions. The implementation of the mathematical model consisted of two main parts: The first has been developed in the frequency domain by applying NEMOH to assess the hydrodynamic coefficients of the object, i.e., the excitation, radiation and added mass coefficients, then, the used mooring system was included in the time-domain model, solving the motion of the floating cylinder, by calibrating the mooring coefficients by comparing the results with the data. The simplicity of the implemented model is a very important feature, and it should be used as a preliminary study to understand the response of moored floating cylinders and others floating bodies under waves.

The performance of non-intrusive instruments, such as acoustic profilers and cameras, to describe the wave-induced flow processes over maritime dike crest was investigated in experiments carried out at the University of Bologna. Direct and derived measurements from the acoustic probes deployed along the structure crest were discussed in relation to the observed backscatter rates. Image processing was implemented by means of clustering algorithm, in order to detect the free surface during overtopping events and characterize wave front propagation over the dike crest. UVP data were processed to indirectly derive flow depths and overtopping rates and compare them with the direct measurements in order to assess the measurement reliability and discuss their limits. Individual overtopping volume distribution as obtained by UVP data were estimated and compared with well-consolidated formulations, showing a good agreement. Finally, suggestions for an appropriate use of non-intrusive instruments to characterize a shallow, transient and aerated flow were provided, such as the control of the artificial seeding density, the use of a bi-static UVP configuration and adjustments to light exposure.

The use of video-monitoring techniques is significantly increased due to the diffusion of high-resolution cameras at relatively low-costs and they are largely used to estimate the shoreline evolution and wave run-up, as important coastal state indicators to be monitored and predicted for the assessment of flooding and erosion risks. In this work, we present an integrated approach based on the results from the low-cost video monitoring systems and the numerical modeling chain by means of SWAN and XBeach to accurately simulate and predict the swash zone processes.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/nLGNneJzmIU

The evolution of coastal and transitional environments depends upon the interplay of human activities and natural drivers, two factors that are strongly connected and many times conflicting. The urge for efficient tools for characterising and predicting the behaviour of such systems is nowadays particularly pressing, especially under the effects of a changing climate, and requires a deeper understanding of the connections among different drivers and different scales. To this aim, the present paper reviews the results of a set of interdisciplinary and coordinated experiences carried out in the Adriatic Sea (north-eastern Mediterranean region), discussing state-of-the art methods for coastal dynamics assessment and monitoring, and suggests strategies towards a more efficient coastal management. Coupled with detailed geomorphological information, the methodologies currently available for evaluating the different components of relative sea level rise facilitate a first identification of the flooding hazard in coastal areas, providing a fundamental element for the prioritization and identification of the sustainability of possible interventions and policies. In addition, hydro- and morpho-dynamic models are achieving significant advances in terms of spatial resolution and physical insight, also in a climatological context, improving the description of the interactions between meteo-oceanographic processes at the regional scale to coastal dynamics at the local scale. We point out that a coordinated use of the described tools should be promptly promoted in the design of survey and monitoring activities as well as in the exploitation of already collected data. Moreover, expected benefits from this strategy include the production of services and infrastructures for coastal protection with a focus on short-term forecast and rapid response, enabling the implementation of an event-oriented sampling strategy.

This work presents the results of the numerical study implemented for the natural area of Lido di Spina, a touristic site along the Italian coast of the North Adriatic Sea, close to the mouth of River Reno. High-resolution simulations of nearshore dynamics are carried out under climate change conditions estimated for the site. The adopted modeling chain is based on the implementation of multiple-nested, open-source numerical models. More specifically, the coupled wave-2D hydrodynamics runs, using the open-source TELEMAC suite, are forced at the offshore boundary by waves resulting from the wave model (SWAN) simulations for the Adriatic Sea, and sea levels computed following a joint probability analysis approach. The system simulates presentday scenarios, as well as conditions reflecting the high IPCC greenhouse concentration trajectory named RCP8.5 under predicted climate changes. Selection of sea storms directed from SE (Sirocco events) and E-NE (Bora events) is performed together with Gumbel analysis, in order to define ordinary and extreme sea conditions. The numerical results are here presented in terms of local parameters such as wave breaking position, alongshore currents intensity and direction and flooded area, aiming to provide insights on how climate changes may impact hydrodynamics at a site scale. Although the wave energy intensity predicted for Sirocco events is expected to increase only slightly, modifications of the wave dynamics, current patterns, and inland flooding induced by climate changes are expected to be significant for extreme conditions, especially during Sirocco winds, with an increase in the maximum alongshore currents and in the inundated area compared to past conditions. © 2018 by the authors.

none 6 si The present work describes an operational strategy for the development of a multiscale modeling system, based on a multiple-nesting approach and open-source numerical models. The strategy was applied and validated for the Gulf of Taranto in southern Italy, scaling large-scale oceanographic model results to high-resolution coupled wave-3-D hydrodynamics simulations for the area of Mar Grande in the Taranto Sea. The spatial and temporal high-resolution simulations were performed using the open-source TELEMAC suite, forced by wind data from the COSMO-ME database, boundary wave spectra from the RON buoy at Crotone and results from the Southern Adriatic Northern Ionian coastal Forecasting System (SANIFS) regarding sea levels and current fields. Model validation was carried out using data collected in the Mar Grande basin from a fixed monitoring station and during an oceanographic campaign in October 2014. The overall agreement between measurements and model results in terms of waves, sea levels, surface currents, circulation patterns and vertical velocity profiles is deemed to be satisfactory, and the methodology followed in the process can constitute a useful tool for both research and operational applications in the same field and as support of decisions for management and design of infrastructures. Gaeta, Maria Gabriella; Samaras, Achilleas; Federico, Ivan; Archetti, Renata; Maicu, Francesco; Lorenzetti, Giuliano Gaeta, Maria Gabriella; Samaras, Achilleas; Federico, Ivan; Archetti, Renata; Maicu, Francesco; Lorenzetti, Giuliano

This work presents the approach strategy for the optimization of the coastal defence at a specific site in the Northern Adriatic Sea, the Reno river mouth (Italy). The area is extremely dynamic and vulnerable since exposed to several climate change related effects and in the last decades has suffered strong erosion processes. A rocky revetment covered by a superficial bituminous layer protects this coastal area, but the bad state of conservation makes this defense technique inadequate also during ordinary events. In addition, important morphological variations at the mouth (i.e., the human demolishing of the final part of the right riverside) affected the stability of the protection works and compromised the inland safety. The analysis of multipurpose coastal schemes for flood mitigation and coastal defence of the area is carried out by means of the well-known commercial software MIKE21, that was implemented to simulate waves (SW), currents and levels (HD) and sediment transport (ST). Different sea events from NW (Bora) and SE (Scirocco) were reproduced in the site, also including tidal level, storm surge and river discharge associated to the reproduced storm. Current configuration of the area and alternative defence schemes (i.e. breakwater, groins) to improve coastal protection were simulated and the numerical results were compared in terms of wave load, inundation rate and bed level change. The condition of Bora with the simultaneous presence of high tidal level results to be the most severe event, since the developed longshore current contrasts the river outflow, leading to a high probability of fluvial flooding of the area. The comparative numerical analysis of the different scenarios and configurations allows estimating the optimal coastal protection scheme both in terms of flooding mitigation and erosion reduction and the implemented model can be a useful tool for future studies regarding a so vulnerable and dynamic area.

The present work describes an operational strategy for the development of a multiscale modelling system, based on a multiple–nesting approach and open–source numerical models. The strategy was applied and validated for the Gulf of Taranto in South Italy, scaling large–scale oceanographic model results to high–resolution coupled wave – 3D hydrodynamics simulations for the area of Mar Grande in Taranto Sea. The spatial and temporal high – resolution simulations were performed using the open–source TELEMAC suite, forced by wind data from the COSMO–ME database, boundary wave spectra from the RON Buoy at Crotone, and results from the Southern Adriatic Northern Ionian coastal Forecasting System (SANIFS) regarding sea levels and current fields. Model validation was carried out using data collected in the Mar Grande basin from a fixed monitoring station and during an oceanographic campaign in October 2014. The overall agreement between measurements and model results in terms of waves, sea levels, surface currents, circulation patterns and vertical velocity profiles is deemed to be satisfactory, and the methodology followed in the process can constitute a useful tool for both research and operational applications on the same field and and as support of decisions for management and design of infrastructures.

Numerical modelling has become an essential component of today's coastal planning, decision support and risk assessment. High resolution modelling offers an extensive range of capabilities regarding simulated conditions, works and practices, and provides with a wide array of data regarding nearshore wave- and hydro-dynamics. In the present work, the open-source TELEMAC suite and the commercial software MIKE21 are applied to selected coastal areas of South Italy. Applications follow a scenario-based approach in order to study representative wave conditions in the coastal field; the models' results are intercompared in order to test both their performance and capabilities, and are further evaluated on the basis of their operational use for coastal planning and design. A multiparametric approach for the rapid assessment of wave conditions in coastal areas is also presented, and implemented in areas of the same region. The overall approach is deemed to provide useful insights on the tested models and the use of numerical models – in general – in the above context, especially considering that the design of harbours, coastal protection works and management practices in the coastal zone is based on scenario-based approaches as well.

The effects of climate change with increased sea level and intensity of the extreme storms leads to an increase of the loads and of the expected overtopping at existing seawalls. The inclusion of bull-noses in the design of seawalls seems to significantly reduce the wave overtopping discharge q and may be an effective solution to face climate change while limiting the increase of the seawalls height and the costs. The experimental work by Van Doorslaer et al. (2015), VD hereinafter, is the only systematic study available so far about the effects of bull-noses on the reduction of q. They developed a number of formulae, adopted then by EurOtop (2016), in case the seawall is placed on a dike slope or at the end of a promenade. The work we are proposing here starts from these findings, to analyze a different case: dikes with a finite crest width and an inshore crown wall with and without a bull-nose. The aim is to verify whether the formulae developed by VD can still be used or require some modifications to complete the existing design formulae.

Numerical modelling has become an essential component of today's coastal planning, decision support and risk assessment. High-resolution modelling offers an extensive range of capabilities regarding simulated conditions, works and practices and provides with a wide array of data regarding nearshore wave dynamics and hydrodynamics. In the present work, the open-source TELEMAC suite and the commercial software MIKE21 are applied to selected coastal areas of South Italy. Applications follow a scenario-based approach in order to study representative wave conditions in the coastal field; the models' results are intercompared in order to test both their performance and capabilities and are further evaluated on the basis of their operational use for coastal planning and design. A multiparametric approach for the rapid assessment of wave conditions in coastal areas is also presented and implemented in areas of the same region. The overall approach is deemed to provide useful insights on the tested models and the use of numerical models – in general – in the above context, especially considering that the design of harbours, coastal protection works and management practices in the coastal zone is based on scenario-based approaches as well.

The role of air modeling is investigated during wave breaking and impact on wall. The paper presents a numerical investigation on the role of air modeling in simulations related to coastal dynamics. The implemented code, named COBRAS2, solves the Favre-Reynolds Navier-Stokes equations for two-phase flows. The k-model is adopted to define the Reynolds stress; the polytropic expression is chosen as the gas state equation to describe air compressibility; the Volume Of Fluid algorithm is implemented in order to track the interface. Simulations of dam-break wave and 1D water piston illustrate the model validity and accuracy, where air inertia and compressibility play a significant role in the reproduced dynamics. Wave breaking is analyzed in comparison with experimental data in order to focus on the influence of air flow in the wave propagation. Finally, air entrapment and compressibility are investigated during the wave impact on deck and on vertical wall and the opportunity to solve the implemented two-phase equations is discussed together with the aim to obtain accurate estimation of wave-induced loads.

Scopo di questo lavoro è presentare alla comunita scientifica italiana il progetto TESSA e le attività che il gruppo dell’Università di Bologna, insieme agli altri partner quali CMCC e CNR-IAMC, sta conducendo all’interno di esso. Il TESSA (Programma PON 01_2823) TEcnologie per la 'Situational Sea Awareness SSA' è un progetto di ricerca industriale che nasce con l'obiettivo di potenziare e consolidare il servizio di oceanografia operativa nell’ Italia meridionale. L'attività di ricerca si propone di sviluppare una serie di prodotti e servizi basati su nuovi dati ambientali risultati da modelli previsionali consolidati dell’oceanografia operativa, integrandoli su piattaforme tecnologiche d’avanguardia (smart phone, tablet, etc) per la loro fruizione da parte di utenti finali del settore marittimo, di quello turistico e della protezione ambientale, interessati a informazioni sullo stato del mare (stato ondoso, livello del mare, correnti, temperatura e salinità), oltre che alle previsioni atmosferiche.

Filtration through porour media is one of the main processes that take place in the interaction between waves and Low Crested Structures (LCSs). The paper analyzes filtration flow patterns and velocity fields inside and around porous media through wave flume experiments and 2DV numerical simulations using the COBRAS (Cornell Breaking Waves and Structures) code. The modelcapability to reproduce different resistance patterns is verified on a wide range of experiments on porous structures considering small and large scale. Since the model doesn't present unique calibration parameters, the original code has been enhanced introducing a filtration formula that explitely describes the resistance dependence on the Reynolds number.

The proposed paper aims to verify the capacity of the flushing channel to guarantee an appropriate water recirculation in the Canouan marina (Caribbean) during tides. Effects of different geometries for the flushing channel and the main harbor entrance are investigated by means of 2DH numerical model. The results, presented in terms of velocity field in the basin and residence time of released colored water, reveal the stronger influence in the water quality of the marina of channel/entrance depth with respect to their width. An efficient managing of the marina (maintenance strategy) is therefore advisable to optimize the water circulation inside the basin.

No other environmental variable of ecological importance to estuarine and coastal marine ecosystems around the world has changed so drastically, in such a short period of time, as dissolved oxygen. Coastal surveys in United States and Europe found that a staggering 78 % of the assessed continental U.S. coastal area and approximately 65 % of Europe’s Atlantic coast exhibit symptoms of eutrophication. The 65 % of the coasts counted by Diaz does not take into account inland seas like the Adriatic or Baltic Seas but also for these, eutrophication and consequently anoxia are common problems. In the present study a simple and economic device is proposed to enhance vertical mixing processes and to induce aeration of deep water by pumping of oxygen-rich surface water downwards to a desired depth around the halocline. The hydrodynamic parameters of the device are estimated through free oscillation tests. Preliminary values of the downward water flux velocity inside the device and the movements of the floater under the action of 4 regular waves, characterizing of the wave climate in the Nord Adriatic Sea, are estimated.

The main parameter for the assessment of coastal vulnerability and sediment transport is the wave run-up on the beach, defining the limit of maximum flooding, but also hydrodynamic properties in the Swash Zone (SZ) are trivial for the comprehension of hydro-morphodynamic processes. Several studies have been carried out on the SZ but few literature is still available on the run-up and on SZ flows on beaches protected by Low Crested Structures (LCSs), where flow motion is driven by a combination of low frequency infra-gravity waves and incident waves. In presence of breakwaters, swash incident waves are transmitted through the structure. In the transmission area behind the structures, wave energy is shifted to higher frequencies with respect to the incident wave spectrum and in general its mean period considerably decreases with respect to the incident one. Collecting in situ run-up measurements during storms is essential to understand the SZ processes and properly calibrate their both empirical and numerical models but measuring extreme run-up is difficult, due to the severe sea conditions and due to unexpected nature of storms. The present paper present a numerical and experimental analysis of the wave run-up and of the flow properties on a beach: the study shows the different behavior of unprotected and protected beach, subjected to the same wave conditions. In particular the paper shows that submerged breakwaters reduce in general the run-up height, on the basis of the calibrated 2DV numerical simulations, under extreme wave conditions (TR >50 years), the effect of submerged breakwaters seems to be negligible on the run-up height. Moreover a preliminary empirical equation for run-up with protected beach is proposed

The large-scale experiments described herein were carried out at Forschungs-Zentrum Küste (FZK), Hannover (Germany) by a research team composed by the Universities of Bologna, Edinburgh, Southampton, Plymouth and the Coast & Harbor Engineering Inc (USA). Wave-induced loads on close-to-prototype jetties were measured. Experimental evidence indicates the presence of force peaks with a short space-time correlation structure, carried by convective processes with a velocity of the order of the wave celerity. After a 100 Hz sampling, forces on the deck bays and front induced by regular and irregular waves are analyzed, focusing the effects on the wave-in-deck loads of (i) wave irregularity, (ii) air venting and (iii) experiment scale in the evaluation of maximum and quasi-static loads. A comparison with the small-scale results is carried out, but differences could not be directly ascribed to scale effects only.

The large scale experiments described in this paper were carried out at the Large Wave Flume (GWK, Große Wellenkanal) in Hanover (Germany). The research team included Universities of Bologna (IT), Edinburgh (UK), Southampton (UK), Plymouth (UK), HR Wallingford (UK) and Coast & Harbor Engineering Inc (USA). Wave-induced loads on close-to-prototype scale jetties were measured, with particular attention to scale effects due to air content in water. The aim of the paper is to present the tests, describe the impact process and give preliminary results concerning uplift loads.

n. 0206 ARTICULATED CONCRETE MATTRESS FOR SUBMARINE PIPELINE PROTECTION: EVALUATION OF THE WAVE-INDUCED FORCES AND STABILITY ANALYSIS. 1 Author: Gaeta, Maria Gabriella 2 Author: Lamberti, Alberto 3 Author: Ricchieri, Fabio 4 Author: Zurlo, Michela Subsea pipeline Articulated concrete mattress Dynamic force Stability analysis Numerical modeling

This contribution proposes a systematic analysis of the overtopping process at dikes, focused on the statistical description of the extreme flow characteristics across the dike crest. The specific objective of the analysis is the investigation of structures subjected to high run-up levels and low freeboards, under severe or extreme conditions that are likely to occur in the future due to climate change. The adopted methodology is based on the collection of new experimental and numerical tests of wave overtopping at smooth dikes at various crest levels. The reliability of the new data is checked in terms of average overtopping discharge and wave reflection coefficient, against consolidated predicting methods from the literature. An update and refitting of the existing formulae for the prediction of the extreme flow depths and velocities at the dike off-shore edge is proposed based on the experimental and numerical outcomes. The dynamics of the overtopping flow propagation along the dike crest under breaking and non-breaking waves, in emerged and submerged conditions, is investigated. Guidelines to update the state-of-the-art formulae for a more cautious estimation of the water depths and the velocities of propagation of the flow in the landward area are provided.

Scopo della ricerca è la valutazione e la quantizzazione dei processi che determinano la perdita di suolo del bacino idrografico del Fiume Calore. • Sono stati calcolati il valore di deflusso torbido unitario medio annuo (Tu) e la perdita stimata di suolo media annua (A) attraverso l'applicazione dell’Universal Soil Loss Equation (USLE), ed infine Sediment Delivery Ratio. • L’approccio metodologico, indipendentemente dall'area di studio, consente l’individuazione di aree soggette a differenti entità di erosione, fornendo indicazioni utili a prevenire o a mitigare il fenomeno.