Divergence of Sediment Fluxes Triggered by Sea‐Level Rise Will Reshape Coastal Bays

Zhang, Xiaohe; Leonardi, Nicoletta; Donatelli, Carmine; Fagherazzi, Sergio

doi:10.1029/2020gl087862

Cited by 15 publications

(11 citation statements)

References 64 publications

(79 reference statements)

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“…SLR is likely to accelerate in the coming century, adding another 0.28–1.01 m till 2100 (Chen et al., 2017; IPCC, 2021). A worldwide concern is that accretion of coastal tidal flats (mainly the intertidal zones) and salt marshes may not be able to keep pace with an accelerating SLR rate (Best et al., 2018; Zhang et al., 2020), resulting in coastal erosion and shoreline retreat, drowning of salt marshes and habitats, and increased flood risk (Craft et al., 2009; Kirwan & Megonigal, 2013; Lovelock et al., 2015; Valiela et al., 2018). Land subsidence and a decline in river‐borne sediment supply may further exacerbate coastal erosion and wetland losses (Syvitski et al., 2009).…”

Section: Introductionmentioning

confidence: 99%

Reclamation of Tidal Flats Within Tidal Basins Alters Centennial Morphodynamic Adaptation to Sea‐Level Rise

Guo

Zhu

et al. 2022

JGR Earth Surface

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Coastal wetlands provide important habitats that host valuable ecosystems. Currently they are facing increasing pressure from climate change and sea-level rise (SLR). The global SLR has risen by 0.2 ± 0.05 m between 1901 and 2018, with a rate of 3.7 ± 0.5 mm yr −1 in the 2006-2018 periods (IPCC, 2021). SLR is likely to accelerate in the coming century, adding another 0.28-1.01 m till 2100 (Chen et al., 2017;IPCC, 2021). A worldwide concern is that accretion of coastal tidal flats (mainly the intertidal zones) and salt marshes may not be able to keep pace with an accelerating SLR rate (

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Section: Introductionmentioning

confidence: 99%

Reclamation of Tidal Flats Within Tidal Basins Alters Centennial Morphodynamic Adaptation to Sea‐Level Rise

Guo

Zhu

et al. 2022

JGR Earth Surface

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“…Assuming sufficient external sediment supply, accelerated rates of sea-level rise increase hydroperiod and subsequently deposition; without a sufficient sediment source, marsh drowning may result (Friedrichs and Perry 2001). Although sea-level rise may enhance marsh deposition, it can also drive erosion of tidal flats and marsh channels via stronger ebb currents, leading to sediment-flux divergence and a negative system-wide sediment budget (Zhang et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Sediment Dynamics of a Divergent Bay–Marsh Complex

Nowacki

Ganju

2020

Estuaries and Coasts

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Bay–marsh systems, composed of an embayment surrounded by fringing marsh incised by tidal channels, are widely distributed coastal environments. External sediment availability, marsh-edge erosion, and sea-level rise acting on such bay–marsh complexes may drive diverse sediment-flux regimes. These factors reinforce the ephemeral and dynamic nature of fringing marshes: material released by marsh-edge erosion becomes part of a bay–marsh exchange that fuels the geomorphic evolution of the coupled system. The dynamics of this sediment exchange determine the balance among seaward export, deposition on the embayment seabed, flux into tidal channels, and import to the marsh platform. In this work, we investigate the sediment dynamics of a transgressive bay–marsh complex and link them to larger-scale considerations of its geomorphic trajectory. Grand Bay, Alabama/Mississippi, is a shallow microtidal embayment surrounded by salt marshes with lateral erosion rates of up to 5 m year−1. We collected 6 months of oceanographic data at four moorings within Grand Bay and its tidal channels to assess hydrographic conditions and net sediment-flux patterns and augmented the observations with numerical modeling. The observations imply a divergent sedimentary system in which a majority of the suspended sediment is exported seaward, while a smaller fraction is imported landward via tidal channels, assisting in vertical marsh-plain accumulation, maintenance of channel and intertidal-flat morphologies, and landward transgression. These results describe a dynamic system that is responsive to episodic atmospheric forcing in the absence of a strong tidal signal and the presence of severe lateral marsh loss.

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“…Coastal models are generally calibrated with few tidal or velocity gauges because of the high cost of field observations (Zhang et al., 2020). In our study domain, 18 water level stations cover not only the main channel (WLO), but also the complex creeks network, well capturing the delay in tidal propagation and the flow attenuation over the entire system.…”

Section: Discussionmentioning

confidence: 99%

“…Coastal wetlands are natural buffer zones between land and ocean that provide protection from rising seas and storm surges (Fagherazzi et al., 2012, 2020; FitzGerald & Hughes, 2019; Schuersch et al., 2018). Sediment is essential for wetlands, because it promotes accretion that counteracts sea level rise (Donatelli et al., 2018; Ganju et al., 2017; Kirwan et al., 2016; Morris et al., 2002; Zhang et al., 2020). Unfortunately, as results of sediment starvation, loss of these valuable ecosystems is increasing worldwide.…”

Section: Introductionmentioning

confidence: 99%

Improving Channel Hydrological Connectivity in Coastal Hydrodynamic Models With Remotely Sensed Channel Networks

et al. 2022

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Coastal wetlands are nourished by rivers and periodical tidal flows through complex, interconnected channels.However, in hydrodynamic models, channel dimensions with respect to model grid size and uncertainties in topography preclude the correct propagation of tidal and riverine signals. It is therefore crucial to enhance channel geomorphic connectivity and simplify sub-channel features based on remotely-sensed networks for practical computational applications. Here, we utilize channel networks derived from diverse remote sensing imagery as a baseline to build a ~10 m resolution hydrodynamic model that covers the Wax Lake Delta and adjacent wetlands (~ 360 km 2 ) in coastal Louisiana, USA. In this richly-gauged system, intensive calibrations are conducted with 18 synchronous field-observations of water levels taken in 2016, and discharge data taken in 2021. We modify channel geometry, targeting realism in channel connectivity. The results show that a minimum channel depth of 2 m and a width of four grid elements (approximatively 40m) are required to enable a realistic tidal propagation in wetland channels. The optimal depth for tidal propagation can be determined by a simplified cost function method that evaluates the competition between flow travel time and alteration of the volume of the channels. The integration of high spatial-resolution models and remote sensing imagery provides a general framework to improve models performance in salt marshes, mangroves, deltaic wetlands, and tidal flats.

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Divergence of Sediment Fluxes Triggered by Sea‐Level Rise Will Reshape Coastal Bays

Cited by 15 publications

References 64 publications

Reclamation of Tidal Flats Within Tidal Basins Alters Centennial Morphodynamic Adaptation to Sea‐Level Rise

Reclamation of Tidal Flats Within Tidal Basins Alters Centennial Morphodynamic Adaptation to Sea‐Level Rise

Sediment Dynamics of a Divergent Bay–Marsh Complex

Improving Channel Hydrological Connectivity in Coastal Hydrodynamic Models With Remotely Sensed Channel Networks

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