Control of wind-wave power on morphological shape of salt marsh margins

Finotello, Alvise; Marani, Marco; Carniello, Luca; Pivato, Mattia; Roner, Marcella; Tommasini, Laura; D’Alpaos, Andrea

doi:10.1016/j.wse.2020.03.006

Cited by 35 publications

(56 citation statements)

References 90 publications

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“…The effects of biological processes (e.g. salt-tolerant vegetation, benthic animals and micro-organisms) are not accounted for in this study, while many recent studies suggest their importance in sediment and tidal flat dynamics (Chen et al, 2017(Chen et al, , 2020Finotello et al, 2020;Huang et al, 2020). Biological processes can be either stabilizers or de-stabilizers of bed sediment, and their biological behaviours and lifecycles can greatly affect the sediment grain size distribution, not only on the surface of the bed but also inside the bed.…”

Section: Model Capabilities and Limitationsmentioning

confidence: 95%

Simulating the role of tides and sediment characteristics on tidal flat sorting and bedding dynamics

Zhou

Liu

Fan

et al. 2021

Earth Surf Processes Landf

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Understanding sediment sorting and bedding dynamics has high value to unravelling the mechanisms underlying geomorphological, geological, ecological and environmental imprints of tidal wetlands and hence to predicting their future changes. Using the Nanhui tidal flat on the Changjiang (Yangtze) Delta, China, as a reference site, this study establishes a schematized morphodynamic model coupling flow, sediment dynamics and bed level change to explore the processes that govern sediment sorting and bedding phenomena. Model results indicate an overall agreement with field data in terms of tidal current velocities, suspended sediment concentrations (SSCs), deposition thicknesses and sedimentary structures. Depending on the variation of tidal current strength, sand-dominated layers (SDLs) and mud-dominated layers (MDLs) tend to form during spring and neap tides, respectively. Thinner tidal couplets are developed during daily scale flood-ebb variations. A larger tidal level variation during a spring-neap tidal cycle, associated with a stronger tidal current variation, favours the formation of SDLs and tidal couplets. A larger boundary sediment supply generally promotes the formation of tidal bedding, though the bedding detail is partially dependent on the SSC composition of different sediment types.Sediment properties, including for example grain size and settling velocity, are also found to influence sediment sorting and bedding characteristics. In particular, finer and coarser sediment respond differently to spring and neap tides. During neap tides, relatively small flow velocities favour the deposition of finer sediment, with limited coarser sediment being transported to the upper tidal flat because of the larger settling velocity. During spring tides, larger flow velocities transport more coarser sediment to the upper tidal flat, accounting for distinct lamination formation. Model results are qualitatively consistent with field observations, but the role of waves, biological processes and alongshore currents needs to be included in further studies to establish a more complete understanding.

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Section: Model Capabilities and Limitationsmentioning

confidence: 95%

Simulating the role of tides and sediment characteristics on tidal flat sorting and bedding dynamics

Zhou

Liu

Fan

et al. 2021

Earth Surf Processes Landf

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“…These erosion processes led to negative consequences for salt-marsh ecosystems in the Venice Lagoon. Indeed, the salt-marsh area in the Venice Lagoon (Figure 1B) decreased from about 180 km 2 in 1810 to just 43 km 2 today, and the depth of the tidal flats hosting seagrass beds (Figure 1B) increased from 0.5 m in 1810 to 1.5 m today [22,26,32].…”

Section: Figure 1 (A)mentioning

confidence: 99%

The Valuation of Ecosystem Services in the Venice Lagoon: A Multicriteria Approach

D’Alpaos

2021

Sustainability

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Coastal ecosystems are among the most economically valuable and highly threatened on Earth; they provide valuable ecosystem services (ESs) but are severely exposed to climate changes and human pressure. Although the preservation of coastal ecosystems is of the utmost importance, it is often sub-optimally pursued by Governments and Societies because of the high costs involved. We consider salt-marsh ecosystems in the Venice Lagoon as an example of a threatened landscape, calling for innovative, integrated management strategies, and propose an application-driven methodological framework to support policymakers in the identification of cost-effective incentive policies to ecosystem preservation. By combining group decision-making and Value-Focused-Thinking approaches, we provide a multiple-criteria decision model, based on pairwise comparisons, to identify which ESs are top-priority policy targets according to a cost-effective perspective. We implemented an online Delphi survey process and interviewed a pool of experts who identified “recreation and tourism”, “coastal protection from flooding”, “carbon storage”, “biodiversity and landscape”, and “nursery habitats for fisheries” as the five most relevant ESs for the Venice Lagoon taking into consideration the Environmental, Economic, and Social perspectives. Our results suggest that the Environmental perspective is the most important criteria, whereas “biodiversity and landscape” is acknowledged as the most important ES.

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“…The present-day configuration of the lagoon is characterized by the presence of sparse salt marshes (Finotello et al, 2020b) undergoing rapid erosion in the last two centuries (D'Alpaos, 2010;Tommasini et al, 2019), wide subtidal platforms, and tidal flats that are cut by intertidal and subtidal channels (Finotello et al, 2019;Ghinassi et al, 2019) (Fig. 1A).…”

Section: Geological Settingmentioning

confidence: 99%

An integrated approach to determine three‐dimensional accretion geometries of tidal point bars: Examples from the Venice Lagoon (Italy)

et al. 2020

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Low rates of lateral migration (centimetres to decimetres per year) combined with relatively high rates of vertical accretion (millimetres to centimetres per year) recorded in microtidal channels of the Venice Lagoon (Italy) give rise to point-bar geometries and internal facies arrangements that differ substantially from widely accepted models of point-bar sedimentary architecture. In this study, field data from the Venice Lagoon are combined with a three-dimensional forward stratigraphic model, the 'Point-Bar Sedimentary Architecture Numerical Deduction' (PB-SAND), to predict the stratal geometries of point bars formed in aggradational settings. The PB-SAND uses a combined geometric and stochastic modelling approach that can be constrained by field evidence. The model applied determines the geometry of four point bars generated by 9 to 11 m wide channels cutting through salt marshes. An iterative best-fit modelling approach has been used to obtain multiple simulations for each case study, each of which fits the observations derived from the analysis of time-series historical aerial photographs and 44 sedimentary cores. Results demonstrate how the geometry of the bars is determined by the development of two key stratal surfaces: the point-bar brink and channel-thalweg surfaces. These surfaces are defined by the progressive translation and vertical shift of the point-bar brink (i.e. break of slope between bar top and bar slope) and the channel thalweg (i.e. deepest part of the channel) during bar evolution. The approach is used to: (i) reconstruct three-dimensional point-bar geometries; (ii) propose alternative reconstructions; (iii) provide insight to drive the acquisition of additional data to better constrain the proposed models; and (iv) provide insight into the mechanism of bar growth for slowly migrating channels in settings subject to relatively high rates of aggradation. This study highlights how interaction between styles of planform transformation and latero-vertical shifts of meandering channels can determine the geometry of related sedimentary bodies. Keywords Aggradation, channel-thalweg trajectory, point-bar brink trajectory, tidal meander, Venice Lagoon. negligible with respect to lateral migration processes. Hence, point bars are commonly described as purely laterally accreting bodies

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Control of wind-wave power on morphological shape of salt marsh margins

Cited by 35 publications

References 90 publications

Simulating the role of tides and sediment characteristics on tidal flat sorting and bedding dynamics

Simulating the role of tides and sediment characteristics on tidal flat sorting and bedding dynamics

The Valuation of Ecosystem Services in the Venice Lagoon: A Multicriteria Approach

An integrated approach to determine three‐dimensional accretion geometries of tidal point bars: Examples from the Venice Lagoon (Italy)

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