1,721,017 research outputs found
Il tempo di vita dei ripascimenti artificiali
No full textIl presente lavoro richiama i criteri di progettazione e gestione dei ripascimenti artifi-ciali ripresi dalla letteratura tecnica. Questo tipo di intervento è molto richiesto su spiag-ge di particolare pregio poiché induce un impatto ambientale nettamente inferiore ri-spetto alle opere rigide tradizionali. Le principali controindicazioni evidenziate nel pre-sente lavoro consistono nel difficile reperimento di idonei volumi di sabbie compatibili (per granulometria e composizione mineralogica) e nella scarsa durabilità. Quest’ultimo aspetto impone un’attenta analisi sulla sostenibilità finanziaria, che può essere garanti-ta da un accurato piano di gestione nel lungo periodo, nonché da interventi da realizza-re ad integrazione del ripascimento. In generale, l’obiettivo da perseguire è quello di aumentare il tempo di vita dell’intervento, riducendo i costi per ricariche periodiche del litorale
Numerical analysis of infiltration in a drained beach
No full textThe beach drainage system (BDS) is a 'soft' engineering solution for coastal protection and management. It artificially increases beach permeability by inducing the groundwater table lowering and, consequently, it favours the infiltration of sea water inside the beach. The new hydrodynamic condition would produce a reduction of the offshore sediment transport and the settlement of the suspended load. The present work focuses on a numerical simulation of infiltration processes in drained conditions by using the HYDRUS-2D code. The groundwater flow through a partially saturated porous media is described by using the well-known Richard's equation. Numerical results are then compared with experimental ones obtained during an intensive experimental program performed at the Grosser Wellen-Kanal in Hannover on a BDS prototype. Moreover, different beach permeabilities (ranging from silt to coarse sand) and different drain altimetric positions are numerically simulated. These analyses allow to draw some first considerations about BDS design criteria. In particular, a 'limit drain depth', strictly related to beach permeability, is defined as the maximum depth that produces the maximum water table lowering and, as a consequence, the best system efficacy in drying the porous mediu
Assessment of wave energy potential around Apulia Region
No full textThe paper shows a preliminary analysis of the estimation of available wave energy around Apulian coasts. Recently, a wave Atlas of Italian seas has been published, displaying the yearly mean wave power, based on the three-hourly wave data set collected by the Italian Wave Network. For the Apulian Region, the buoy belonging to the IWN is placed offshore Monopoli (Bari). In the present work the estimation of the average wave power offshore Apulian costs is integrated with the analysis of wave data recorded by two wave buoys placed offshore Tremiti Islands and Taranto, respectively. The analysis has allowed to estimate a yearly mean wave energy flux equal to about 2 kW/m for Monopoli and Tremiti Islands buoys and to 1.4 kW/m in the Ionian sea. In the full paper the analysis of both wave power and energy are deeply described and the yearly and seasonal mean values are showed and discussed
Groundwater Flow On A Drained Beach
No full textThe paper deals with the analysis of the groundwater flow in a drained beach. Infiltration processes in static conditions (without running waves) are numerically simulated by using the \textitHYDRUS-2D software.\\
Nevertheless field and laboratory experiences give the possibility to study the influence of the system on both nearshore hydrodynamics and morphodynamics, a numerical model, able to reproduce the drainage main physical processes, is fundamental in order to define the main BDS design criteria which, to date, are not yet defined.\\
The groundwater flow through a partially saturated porous media is described using Richard's equation. Numerical results are then compared with the experimental ones obtained during an intensive experimental program performed on a Beach Drainage System (BDS) prototype at the GrosserWellen Kanal (GWK) in Hannover. In particular, the study focuses on the BDS influence on the groundwater table inside the beach and drained flows
Nearshore morphodynamic of a drained beach
No full textThe paper deals with a morphological study on a drained beach, under different wave conditions.
The Beach Drainage System (BDS) should artificially increase beach infiltration capacity by installing a drain under the beach face. The system produces a water table lowering and, consequently, an increasing of unsaturated zone (Damiani et Al.,2009); moreover, a vertical infiltration flow increases effective weight of grains, producing a better stability. According to the above hydrodynamic effect, BDS should influence cross-shore sediment transport in the shore zone.
Many BDS prototypes have been installed around the world; also in Italy, some examples are available, i.e. Ostia (Damiani et Al.,2003), Alassio and Procida (Vicinanza et Al.,2009). Field monitoring is very useful to assess the effectiveness of the system, even if with uncertainties in results, affected by the impossibility to control the boundary conditions. Laboratory tests (Damiani et Al.,2009) could be used in defining how does the system work in different wave conditions and drain configurations
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