Morphodynamic evolution of a microtidal barrier, the role of overwash: Bevano, Northern Adriatic Sea

This study discusses the morphological changes of the Bevano “microtidal barrier” and the washover dynamics and evolution in response to several storm surges recorded during one year between September 2008 and September 2009. This barrier corresponds to the old Bevano river spit (characterised by a northward migration) which was abandoned after the relocation of the river mouth some 600 m to the south of the previous inlet position. The first overwash event was recorded in this barrier just after one of the highest surges recorded in the last 100 years (01 December 2008) with a surge level of 0.97 m above MSL, combined with an offshore significant wave height of 1.45 m (measured at Cesenatico). Seven separate washover fans were identified together with severe damages to fences and dune vegetation. The washover fans had different dimensions, the most important one being around 18 m wide, and generating a ~ 9 m landward migration of the back-barrier limit. The study area was therefore subjected to a series of storm-surges during the study period with surge values fluctuating between 0.6 m and 0.8 m. The overwash processes and particularly the exceptional surge of 01 December 2008 was the instigator of initial morphological changes which then facilitated successive morphological changes caused by the subsequent storm surges and, as a result, generating the complete change of the morphologic configuration of the microtidal setting

Morphodynamic evolution of a microtidal barrier, the role of overwash: Bevano, Northern Adriatic Sea

ICS2011 (Proceedings) Poland - consultable à l'adresse suivante : www.ics2011.pl/.../SP64_696-700_M.Sedrati.pdfInternational audienceThis study discusses the morphological changes of the Bevano "microtidal barrier" and the washover dynamics and evolution in response to several storm surges recorded during one year between September 2008 and September 2009. This barrier corresponds to the old Bevano river spit (characterised by a northward migration) which was abandoned after the relocation of the river mouth some 600 m to the south of the previous inlet position. The first overwash event was recorded in this barrier just after one of the highest surges recorded in the last 100 years (01 December 2008) with a high a surge level of 0.97 m, combined with an offshore significant wave height of 1.45 m (measured at Cesenatico). Seven separate washover fans were identified together with severe damages to fences and dune vegetation. The washover fans had different dimensions, the most important one being around 18 m wide, and generating a ~ 9 m landward migration of the back-barrier limit. The study area was therefore subjected to a series of storm-surges during the study period with surge values fluctuating between 0.6 m and 0.8 m. The overwash processes and particularly the exceptional surge of 01 December 2008 was the instigator of initial morphological changes which then facilitated successive morphological changes caused by the subsequent storm surges and, as a result, generating the complete change of the morphologic configuration of the microtidal setting

Morphodynamic evolution of a microtidal barrier, the role of overwash: Bevano, Northern Adriatic Sea

ICS2011 (Proceedings) Poland - consultable à l'adresse suivante : www.ics2011.pl/.../SP64_696-700_M.Sedrati.pdfInternational audienceThis study discusses the morphological changes of the Bevano "microtidal barrier" and the washover dynamics and evolution in response to several storm surges recorded during one year between September 2008 and September 2009. This barrier corresponds to the old Bevano river spit (characterised by a northward migration) which was abandoned after the relocation of the river mouth some 600 m to the south of the previous inlet position. The first overwash event was recorded in this barrier just after one of the highest surges recorded in the last 100 years (01 December 2008) with a high a surge level of 0.97 m, combined with an offshore significant wave height of 1.45 m (measured at Cesenatico). Seven separate washover fans were identified together with severe damages to fences and dune vegetation. The washover fans had different dimensions, the most important one being around 18 m wide, and generating a ~ 9 m landward migration of the back-barrier limit. The study area was therefore subjected to a series of storm-surges during the study period with surge values fluctuating between 0.6 m and 0.8 m. The overwash processes and particularly the exceptional surge of 01 December 2008 was the instigator of initial morphological changes which then facilitated successive morphological changes caused by the subsequent storm surges and, as a result, generating the complete change of the morphologic configuration of the microtidal setting

Morphodynamics of a microtidal protected beach during low wave-energy conditions

This paper presents detailed hydrodynamic and morphological data from a field experiment spanning 5 days (10 tidal cycles, starting at Spring Tide conditions) undertaken in Lido di Dante, a microtidal protected beach in the Northern Adriatic Sea. This microtidal beach experienced intense erosion in the recent past and therefore it has been protected by groins, nourishments and a semi-submerged breakwater (Low-Crested Structures). During the fieldwork, an intertidal swash bar formed at spring tide under very low wave-energy conditions. The swash bar migrated 3.5 m landwards during two consecutive tides when the measured maximum significant wave height at the upper beach was around 0.2 m. This migration was associated with an onshore sediment transport, resulting from the erosion of the bar's seaward slope. Once the tidal range decreased during the last tides and wave action ceased, the swash bar became static and only some non-significant changes were observed on both seaside slope and bar slip-face. The net volumetric change of this beach during the fieldwork was non-significant, in spite of the swash bar landward migration (cross-shore redistribution of the initial beach sediment budget). The wave attenuation generated by the beach protection structures was highlighted through comparison between wave measurements inside and outside the barrier. This had a significant role on swash processes and tide controlled duration of swash action, which controlled the cross-shore bar's morphodynamice in the absence of significant longshore processes

Morphological change by overwash on a microtidal backshore: Bevano beach, Northern Adriatic Sea

none5noneSedrati M.; Ciavola P.; Armaroli C.; Fontana E.; Masina M.Sedrati, Mouncef; Ciavola, Paolo; Armaroli, Clara; Fontana, Elisa; Masina, Marinell

Morphodynamics of a microtidal protected beach during low wave-energy conditions

This paper presents detailed hydrodynamic and morphological data from a field experiment spanning 5 days (10 tidal cycles, starting at Spring Tide conditions) undertaken in Lido di Dante, a microtidal protected beach in the Northern Adriatic Sea. This microtidal beach experienced intense erosion in the recent past and therefore it has been protected by groins, nourishments and a semi-submerged breakwater (Low-Crested Structures). During the fieldwork, an intertidal swash bar formed at spring tide under very low wave-energy conditions. The swash bar migrated 3.5 m landwards during two consecutive tides when the measured maximum significant wave height at the upper beach was around 0.2 m. This migration was associated with an onshore sediment transport, resulting from the erosion of the bar's seaward slope. Once the tidal range decreased during the last tides and wave action ceased, the swash bar became static and only some non-significant changes were observed on both seaside slope and bar slip-face. The net volumetric change of this beach during the fieldwork was non-significant, in spite of the swash bar landward migration (cross-shore redistribution of the initial beach sediment budget). The wave attenuation generated by the beach protection structures was highlighted through comparison between wave measurements inside and Outside the barrier. This had a significant role on swash processes and tide controlled duration of swash action, which controlled the cross-shore bar's morphodynamics in the absence of significant longshore processes

TiO2 waveguides thin films prepared by sol-gel method on glass substrates with and without ZnO underlayer

TiO2 thin films have been deposited on glass substrates with and without ZnO underlayer by sol-gel dip coating process. XRD patterns show the formation of anatase phase with the diffraction lines (1 0 1) and (2 0 0) in TiO2/glass sample. In TiO2/(ZnO/glass) sample, TiO2 is composed of anatase phase with the diffraction line (2 0 0) but the diffraction peaks of ZnO wurtzite are also well-defined. The determination of the refractive index and the thickness of the waveguiding layers has been performed by m-lines spectroscopy. The thickness of TiO2 thin films deduced by Rutheford Backscattering Geometry (RBS) agrees well with that obtained by m-lines spectroscopy. TiO2/glass sample exhibits one guided TE0 and TM0 polarized modes. In TiO2/(ZnO/glass) sample, only, TE0 single mode has been excited due to cutoff condition