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Reliable descriptions of erosion events are foundational to effective frameworks relevant to the fate of tidal landscape evolution. Besides the rhythmic, predictable action of tidal currents, erosion in shallow tidal environments is strongly influenced by the stochastic wave-induced bottom shear stress (BSS), mainly responsible for sediment resuspension on tidal flats. However, the absence of sufficiently long, measured time series of BSS prevents a direct analysis of the combined tide- and wave-driven erosion dynamics and its proper representation in long-term morphodynamic models. Here we test the hypothesis of describing erosion dynamics in shallow tidal environments as a Poisson process by analysing, with the peak-over-threshold theory, the BSS time series computed using a fully coupled, bi-dimensional numerical model. We perform this analysis on the Venice Lagoon, Italy, taking advantage of several historical surveys done in the last 4 centuries, which allow us to investigate the effects of morphological modifications on spatial and temporal erosion patterns. Our analysis suggests that erosion events on intertidal flats can effectively be modelled as a marked Poisson process in different morphological configurations because the interarrival times, durations, and intensities of the over-threshold exceedances are always well described by exponentially distributed random variables. The resulting statistical characterization allows a straightforward computation of morphological indicators, such as the erosion work, and paves the way for a novel synthetic, yet reliable, approach for the long-term morphodynamic modelling of tidal environments. [ABSTRACT FROM AUTHOR]

Altomare, C., Gentile, G.M., 2013. An innovative methodology for the re-naturalization process of a shingle beach The gravel beach of Torre del Porto (Italy) was affected by a huge erosive phenomenon during the last 30 years. The causes which led to the erosion and the design lines through which to obtain the re-naturalization have been identified. Following a new methodological approach, the project consisted of entrusting assorted rubble stones with a proper weight to the area. Consequently the natural formation process can unfold again its effectiveness and the beach is recreated. The monitoring of the sediment transport was essential to provide the information about the correct results of prediction and analysis of the nourishment. The methodology, results and monitoring phases are described in this paper. [ABSTRACT FROM AUTHOR]

Abstract: Occupation of the coast has significantly increased in recent decades, mostly due to a greater demand for recreation and tourism. Today, erosion threatens many human-made structures and activities, requiring an integrated approach for the understanding of coastal dynamics and identification of alternatives to associated problems. This study investigates a 64km-long coastal physiographic unit in the northern microtidal littoral of Tuscany (Italy). Vertical aerial photographs and direct field surveys were used to retrieve changes in shoreline position over 1938–1997 and 1997–2005 time intervals. Significant beach accretion was observed during the first period updrift of Carrara (84m) and Viareggio (280m) harbours and at Marina di Pietrasanta (100m), whereas severe erosion occurred downcoast of Carrara harbour (−130m, at Marina dei Ronchi) and on the northern side of Arno river mouth (−400m). Similar trends were observed between 1997 and 2005; beach slope between the 1997 shoreline position and the closure depth correlated well with the distribution of erosion/accretion patterns from the 1938–1997 period (slopes were lower in eroded areas than at sites under accretion). Longshore distribution of erosion/accretion patterns was controlled by coastal compartmentalisation. Three of the main littoral cells were mostly formed by natural limits (i.e., Punta Bianca promontory, Marina di Pietrasanta, the Arno river mouth and the port of Livorno). Several sub-cells were created within these cells due to the introduction of human-made structures (such as Carrara and Viareggio harbours), which formed artificial fixed limits that allowed the transport of sediments (exclusively fines) in one direction only. Results will help improve the understanding of coastal processes and manage littoral sediment transport in a sustainable manner. This will reduce the need for structural interventions, such as breakwaters and groynes, which in the past decades prevented coastal retreat at local scale but shifted erosion downdrift, leading to degradation of the investigated area and requiring continuous maintenance. [Copyright &y& Elsevier]

Abstract: The hydrologic regime of the Tiber River basin in central Italy has been impacted considerably in the last decades by intensive anthropic activities, and hydraulic works in particular (e.g. hydropower reservoirs, land use modification). In the Tiber River the wash load, in particular, plays an important role in sediment transport, and the knowledge of this hydrological variable is very important for the evaluation of medium–long-term dynamic of shoreline, and the evaluation of reservoir landfill. The Ripetta flow gauge, located in downtown Rome, has been continuously monitoring the daily discharge for decades, while daily sediment load measurements are available only for short terms. In this research, the yearly sediment rate is simulated using a simple stochastic model based on the evaluation of sediment rating curves. The sediment rating curve, i.e. the average relation between discharge and suspended sediment concentration for a specific location, is estimated using a power law model. The fitting curve, obtained by regression analysis, lacks the physical characterization of the phenomenon, often represented by the empirical evidences of erosion severity and the erosional power of river. Model results provide useful insights on the impact of recent hydraulic works on the sediment transport regime. [Copyright &y& Elsevier]

We propose an experimental setup to measure soil erosion and related it with sediment transport using rainfall simulator on a large plots experimental area. Experiments were carried out in fulfilment of the HERASE project, aimed at investigating the seasonal variations of soil erosion in the Oglio basin, an Alpine and Pre-alpine watershed with an area of about 1800 km2, and maximum elevation of 3.538m a.s.l. Namely some rainfall simulation experiments were carried out to assess water erosion under three different scenarios, on in situ plots having same soil and slope, but with different soil coverage and initial moisture condition. In particular, two experiments were carried out on a grassland plot covering an area of 144m2, one considering an undisturbed initial soil moisture condition and the other on a wet soil. The third experiment plot, having the same soil and slope of the previous, and covering an area of 72m2, was set up in the pine forest underwood area. The duration of the three experiments were respectively of 18 minutes, 30 minutes and 30minutes and rainfall intensity was set equal to 70mm/h, accordingly to a 200 return period storm. The plots were properly designed to ensure a correct as possible measure of surface runoff, and transported sediments were collected at 1 minute steps. Suspended sediment, and particle size analysis were carried out ex-post. Our results show a different behaviour of the two analysed plots, in terms of runoff generation and sediment transport. The runoff peak on grassland ranged from 0.018l/s for the undisturbed condition, to 0.09l/s with wet initial condition, while the peak in sediment transport, slowly delayed with respect to the runoff peak, was 1,7 times bigger in wet conditions. In the third experiment, peak runoff was 0.9l/s (10 times bigger than the peak runoff on wet grassland), and constant until the end of simulated rainfall, and took five minutes to run out (concentration time). The analysis on sediment shows an initial slush, where pine needles composed the majority of sediment. Then, after the sediment reached the peak of 350mg/s after about 9 minutes from the beginning of the experiment, it decreased rapidly to an almost constant value of 50mg/s. Interpretations on experiment results with different formulations and a comparison with similar analyses carried out in the Alpine area of Italy are proposed. [ABSTRACT FROM AUTHOR]