SEDTRANS96: upgrade and calibration of the GSC sediment transport model

Amos, C L

doi:10.4095/209240

Cited by 5 publications

(2 citation statements)

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“…Lido inlet, in particular, was considered depositional. Defendi et al [88] measured the total transport in the Lido inlet based on calibrated ADCP measurements in 2005-2006 and by coupling the transport model SEDTRANS96 ([89], [90]) to the SHYFEM hydrodynamic model ([91]; [92]), showing a sediment loss of 381 ⋅ 10 3 m 3 /year for the lagoon and of 256 ⋅ 10 3 m 3 /year for the Lido inlet, with a bed-load transport of 29 ⋅ 10 3 m 3 /year. These studies referred to the inlet before the most recent modifications.…”

Section: Discussionmentioning

confidence: 99%

Tidal inlet seafloor changes induced by recently built hard structures

et al. 2019

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Tidal inlets are extremely dynamic environments that are often strongly modified by anthropogenic intervention. In this study, we describe the rapid evolution of a highly human-impacted tidal inlet, studied through repeated high-resolution multibeam surveys and geomorphometric analysis. We document the rapid change induced by new hard coastal structures built to protect the historical city of Venice (Italy). A new breakwater erected between 2011 and 2013 induced the formation of large scour holes with the consequent erosion of about 170 · 103 ± 15.6% m3 of sediment until 2016. The construction of a new island in the middle of the inlet and the restriction of the inlet channel caused a general change of the inlet sedimentary regime from depositional to erosive with a net sediment loss of about 612 · 103 ± 42.7% m3, a reduction of the dune field area by more than 50% in about five years, and a coarsening in the sediment distribution. Our results give new insight on the tidal inlet resilience to changes, distinguishing two different phases in its recent evolution: (i) a very rapid response (from 2011 to 2013) of the seafloor morphology with scour-hole erosion at the new breakwater tips at a rate of about 45⋅103 m3/year and the disappearing of dune fields at a rate of 104⋅103 m2/year; and (ii) a general slowdown of the erosive processes from 2013 to 2016. Nevertheless, the erosion continues at the breakwater, though at a reduced rate, possibly representing a threat to the hard structure. In view of global mean sea level rise and consequent proliferation of hard structures along the coast all over the world, the combined use of very high resolution multibeam surveys and repeatable geomorphometric analysis proposed in this study will be crucial for the monitoring and future management of coastal environments.

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Section: Discussionmentioning

confidence: 99%

Tidal inlet seafloor changes induced by recently built hard structures

et al. 2019

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“…Plotting values from field data (Li and Amos 1995) and from generalized cases produced by the SEDTRANS model (Li and Amos 1997;Davidson 2001) on the diagram suggests that the plane-bed limit should form a steeper curve than the one drawn by Myrow and Southard (1991) (Fig. 11).…”

Section: Bedformsmentioning

confidence: 92%

Combined-Flow Processes and Sedimentary Structures on the Shoreface of the Wave-Dominated Grande-Riviere-de-la-Baleine Delta

Hill¹,

Meulé²,

Longuépée³

2003

Journal of Sedimentary Research

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Shoreface sediments exposed in raised deltaic deposits along the Hudson Bay coast are characterized by a thick succession of predominantly parallel-laminated and small-scale cross-laminated fine sand. Ripple forms, where preserved, include both combined-flow and wave-ripple geometries. Hummocky cross stratification is present in lower parts of the section. Similar facies have been found in cores from the present-day shoreface. Measurements of waves, currents, and suspended sediment concentrations in 10 m water depth, conducted over a 15-day period in the fall of 1999, captured four different meteorological periods. These included an intense four-day storm which sustained significant wave heights over 3 m for 15 hours and a storm surge of over 1 m height. Fair-weather conditions produce weak alongshore tidal flows, but oscillatory motions generated by small local waves predominate. During storms, orbital motions dominate the flow but a strong inertial flow generated by wind forcing is also present. Comparison with a published combined-flow bedform-stability diagram suggests that the predominant bedforms at 10 m depth would be small 2-D wave-dominated ripples and small, weakly asymmetrical 3-D ripples under fair-weather conditions and large 3-D ripples and upper plane bed under storm wave conditions. The predominantly interbedded parallel-laminated and small-scale cross-laminated facies is therefore interpreted to be characteristic of the upper shoreface, where the seabed experiences intense oscillatory motions under all storms andeven some fair-weather conditions. Combined-flow ripples would form during storm events because of the stronger wind-driven mean residual current. Hummocky cross-stratification forms in deeper water during storms where the ratio of maximum orbital velocity to mean residual current velocity remains for longer periods in the large 3-D ripple field during the waning phase of storms. A numerical bed predictor model, using the 15-day data set as input, also suggests bimodal conditions fluctuating between wave ripples and upper plane bed at 10 m water depth. This model further indicates that combined-flow ripples would form rarely, but tends to underestimate the threshold of sediment suspension.

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A model of sand transport in Treporti channel: northern Venice lagoon

et al. 2006

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The origin of the sands in the Venice lagoon has been the subject of an extensive field survey in parallel with numerical modelling. Four transects along Treporti and Burano canals were conducted from which 33 bottom sediment samples were collected. These samples were analysed for grain size and sorting to examine any trends in the granulometry of these sediments that might shed light on transport paths. The modelling study consists of three parts: the sediment transport model SEDTRANS96 was used with a finite-element hydrodynamic model (SHYFEM) and an empirical wave model (US Army Corps of Engineering) to simulate sand transport in the Treporti canal. A type of link box model was created where finite elements of the hydrodynamic model have been combined to macroboxes on which the water and sediment flux over the sections, and a mass balance has been computed. Several grain size classes were simulated; the distributions before and after the simulation were examined. Idealised wind and tidal values were initially used to force 12 h simulations to test the sediment transport sensitivity. Finally, a full-year simulation (1987) has been carried out using measured tidal and wind data. Only a part of Venice lagoon was covered by the simulation: a major channel (Treporti) running from Lido inlet towards the northern lagoon. The total sand transport through all of the sections was computed for 1 year. Sediment mass balance was determined, and the resulting trends of erosion and deposition were computed. There were no trends in the median grain diameter and sorting of bottom samples from the Treporti canal; all sands were fine (120 μm, one outlier of 300 μm was removed). The absence of a trend in grain size suggests that there is no significant import of sand to the lagoon through the Lido inlet. The results from the simulations seem therefore to confirm the hypothesis of reworking of sand within the lagoon. The computed erosion is some centimeters per year diagnostic of channel scouring and enlargement with time. The Treporti canal is subject to strong current velocities of around 1 m/s, which hold fine sand in suspension and thus prevent sedimentation.

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SEDTRANS96: upgrade and calibration of the GSC sediment transport model

Cited by 5 publications

References 0 publications

Tidal inlet seafloor changes induced by recently built hard structures

Tidal inlet seafloor changes induced by recently built hard structures

Combined-Flow Processes and Sedimentary Structures on the Shoreface of the Wave-Dominated Grande-Riviere-de-la-Baleine Delta

A model of sand transport in Treporti channel: northern Venice lagoon

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