117,398 research outputs found
Sea level perturbations caused by Bora in the northern Adriatic
No full textThe Jan. 2014 Bora storm had a measurable impact in the northern Adriatic. At Senigallia, in the wake of the storm, the EsCoSed field experiment (Brocchini et al. in Geology 385:27–40, 2017) recorded 5-cm sea-level fluctuations with a characteristic period of 100 min, exhibiting a distinctive, discrete frequency spectrum. Sea level oscillations of similar height and time periods were also recorded by tidal gauge at Venice. Given the sensitivity of Venice flooding to sea-level perturbations and the localized, basin-transversal jet structure of the Bora winds, the observations are both significant and surprising. We hypothesize that the oscillations were caused by wind setup generated by the Bora jets, and investigate the event using a simplified, linear mathematical model. Model simulations support the wind setup hypothesis and suggest that the oscillations observed were a mixture of edge-waves and two-dimensional seiches with a significant basin-transversal component. The spatial structure of seiches explains the basin-longitudinal reach of Bora storm. A comparison with the analysis of Venice historical records of extreme sea level events, compiled by Ferrarin et al. (Sci Rep 12(1):1–11, 2022), shows that Bora-induced oscillations are of the same order of magnitude as general seiche constituents. Their contribution, however is, much less understood. Further work is needed to evaluate the flooding threat posed by Bora storms
Exploring the Potential Application of Ramp Metering Systems to Improve the Performances of Roundabout Corridors
No full textThis work is part of broader research concerning some innovative topics such as the study of new dynamic simulation-based approaches to improve traffic efficiency and road safety in Roundabout Corridors. In particular, the present paper examines Ramp Metering systems focusing on their application to roundabouts, to improve their efficiency and safety. Ramp Metering, a traffic management strategy traditionally used on freeway on-ramps to control the rate at which vehicles enter the mainline, has been thorough in various contexts but is relatively novel in its application to roundabouts. The first part of the paper aims to analyse how Ramp Metering can mitigate congestion and enhance overall traffic efficiency and safety in roundabouts. Instead in the second part, a new potential application for Roundabout Corridors is introduced, where coordinated Ramp Metering could optimize traffic flow across multiple roundabouts in succession, leading to improvements throughout the artery. The case study analyzed is the congested Roundabout Corridor located in Pisa, Italy. The corridor was analyzed through the Aimsun simulation software, comparing the current state and a possible future project state with the addition of Ramp Metering systems. Finally, this paper also suggests directions for future research, including the development of further Intelligent Transportation Systems (ITS) such as smart cameras that could further improve the effectiveness of Ramp Metering on Roundabout Corridors. The article is divided as follows: Introduction, Ramp Metering systems operations, Roundabout Corridors characteristics, Application of Ramp Metering in Roundabouts, New Implementation for Roundabout Corridors, Conclusions and Future Research works
The modelling of short waves in shallow waters. Comparison of numerical models based on Boussinesq and Serre equation.
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Modelli di calcolo del seup in corrispondenza di barriere sommerse in batteria.
No full textCD-ROM, Paper N. 152, 13p
Lagrangian Observations of Waves and Currents From the River Drifter
No full textThe working principle and the capabilities of a new platform called the River Drifter are here presented. This technology has applications in the study of the hydrodynamics of coastal areas, rivers, and lakes. The River Drifter was designed for shallow water applications (1 m and deeper) to collect concurrent measurements of surface currents, three-dimensional velocity profiles underneath the device, water depth, and salinity. Here, we discuss how water level displacements can be inferred and used to measure the swell characteristics and to also correct the measured velocity. We also show how the local vorticity field can be computed. As an example application, we describe a study whose goal was to investigate the fate of a polluted river plume and how two River Drifters initially following the same path are characterized by very different final trajectories. The different behaviors of the two drifters are explained in terms of the local flow dynamics, which are strongly influenced by the seabed morphology, forcing the River Drifters to move in different directions
Mitiganting the impact on the nearshore hydro-morphodynamics of macrovortices generated at submerged breakwaters
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A comprehensive study of the river plume in a microtidal setting
No full textOn the basis of observations and modelling of the plume generated by the Misa River (AN, Italy), we performed a comprehensive study, which integrated different sources of information (field data, numerical simulations, etc.), of the generation and transport mechanisms of river plumes flowing into microtidal environments. First, we analysed images simultaneously acquired by both two shore-based stations and satellite to determine plume fronts and extensions. Then, we correlated such information with the estuarine forcing to recognize the plume generation and transport mechanisms. Being real-life events influenced by a combination of factors, we run numerical simulations to separately study each force and its influence on the plume evolution. We also performed simulations of two real-life cases, to compare the modelled and observed results. We identified the river discharge and the wind as the main generation and transport mechanisms, respectively. Moreover, waves could stir, suspend, and drag plume sediments, even if results showed that a river discharge associated with a return period smaller than 1 year produced a plume denser than 5-year return period waves. The transport mechanisms were responsible for the alongshore extension of the plume. The tide, even if secondarily, affected the plume evolution, depending on its phase shift to the river discharge peak. Particle Tracking Velocimetry from videos acquired by a shore-based station provided the surface velocity field in the final river stretch. This and the contributions by wind and waves were correlated with the plume extension through a power law
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