scholarly journals The influence of sea level rise and changes in fringing reef morphology on gradients in alongshore sediment transport

2013 ◽  
Vol 40 (12) ◽  
pp. 3096-3101 ◽  
Author(s):  
A. E. Grady ◽  
L. J. Moore ◽  
C. D. Storlazzi ◽  
E. Elias ◽  
M. A. Reidenbach
2011 ◽  
Vol 18 (6) ◽  
pp. 989-999 ◽  
Author(s):  
E. D. Lazarus ◽  
D. E. McNamara ◽  
M. D. Smith ◽  
S. Gopalakrishnan ◽  
A. B. Murray

Abstract. Developed coastal areas often exhibit a strong systemic coupling between shoreline dynamics and economic dynamics. "Beach nourishment", a common erosion-control practice, involves mechanically depositing sediment from outside the local littoral system onto an actively eroding shoreline to alter shoreline morphology. Natural sediment-transport processes quickly rework the newly engineered beach, causing further changes to the shoreline that in turn affect subsequent beach-nourishment decisions. To the limited extent that this landscape/economic coupling has been considered, evidence suggests that towns tend to employ spatially myopic economic strategies under which individual towns make isolated decisions that do not account for their neighbors. What happens when an optimization strategy that explicitly ignores spatial interactions is incorporated into a physical model that is spatially dynamic? The long-term attractor that develops for the coupled system (the state and behavior to which the system evolves over time) is unclear. We link an economic model, in which town-manager agents choose economically optimal beach-nourishment intervals according to past observations of their immediate shoreline, to a simplified coastal-dynamics model that includes alongshore sediment transport and background erosion (e.g. from sea-level rise). Simulations suggest that feedbacks between these human and natural coastal processes can generate emergent behaviors. When alongshore sediment transport and spatially myopic nourishment decisions are coupled, increases in the rate of sea-level rise can destabilize economically optimal nourishment practices into a regime characterized by the emergence of chaotic shoreline evolution.


2019 ◽  
Vol 12 (9) ◽  
pp. 4013-4030 ◽  
Author(s):  
Jaap H. Nienhuis ◽  
Jorge Lorenzo-Trueba

Abstract. Barrier islands are low-lying coastal landforms vulnerable to inundation and erosion by sea level rise. Despite their socioeconomic and ecological importance, their future morphodynamic response to sea level rise or other hazards is poorly understood. To tackle this knowledge gap, we outline and describe the BarrieR Inlet Environment (BRIE) model that can simulate long-term barrier morphodynamics. In addition to existing overwash and shoreface formulations, BRIE accounts for alongshore sediment transport, inlet dynamics, and flood–tidal delta deposition along barrier islands. Inlets within BRIE can open, close, migrate, merge with other inlets, and build flood–tidal delta deposits. Long-term simulations reveal complex emergent behavior of tidal inlets resulting from interactions with sea level rise and overwash. BRIE also includes a stratigraphic module, which demonstrates that barrier dynamics under constant sea level rise rates can result in stratigraphic profiles composed of inlet fill, flood–tidal delta, and overwash deposits. In general, the BRIE model represents a process-based exploratory view of barrier island morphodynamics that can be used to investigate long-term risks of flooding and erosion in barrier environments. For example, BRIE can simulate barrier island drowning in cases in which the imposed sea level rise rate is faster than the morphodynamic response of the barrier island.


Author(s):  
James F. Bramante ◽  
Andrew D. Ashton ◽  
Curt D. Storlazzi ◽  
Olivia M. Cheriton ◽  
Jeffrey P. Donnelly

Eos ◽  
2016 ◽  
Vol 97 ◽  
Author(s):  
Lily Strelich

Scientists examine the role of variables like tides and suspended sediment concentration to improve methods of evaluating coastal wetlands and how they may respond to future sea level rise.


2020 ◽  
Author(s):  
Shuaib Rasheed ◽  
Simon C. Warder ◽  
Yves Plancherel ◽  
Matthew D. Piggott

Abstract. Changes to coastlines and bathymetry alter tidal dynamics and associated sediment transport process, impacting upon a number of threats facing coastal regions, including flood risk and erosion. Especially vulnerable are coral atolls such as those that make up the Maldives archipelago which has undergone significant land reclamation in recent years and decades, and is also particularly exposed to sea level rise. Here we develop a tidal model of Male' Atoll, Maldives, and use it to assess potential changes to sediment grain size distributions under sea level rise and coastline alteration scenarios. The results indicate that the impact of coastline modification over the last two decades at the island scale is not limited to the immediate vicinity of the modified island, but can also significantly impact the sediment grain size distribution across the wider atoll basin. Additionally, the degree of change in sediment distribution which can be associated with sea level rise that is projected to occur over relatively long time periods is predicted to occur over far shorter time periods with coastline changes, highlighting the need to better understand, predict and mitigate the impact of land reclamation and other coastal modifications before conducting such activities.


Geosciences ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 140
Author(s):  
Nicoletta Leonardi ◽  
Xiaorong Li ◽  
Iacopo Carnacina

The impact of tide-induced morphological changes and water level variations on the sediment transport in a tidally dominated system has been investigated using the numerical model Delft3D and South-East England as a test case. The goal of this manuscript is to explore the long-term changes in morphology due to sea level rise and the large-scale morphodynamic equilibrium of the South-East England. Our results suggest that the long term (century scale) tidally-induced morphological evolution of the seabed slows down in time and promotes a vanishing net transport across the large scale system. Century-scale morphologically updated simulations show that both morphological changes and net transport values tend to decrease in time as the system attains a dynamic equilibrium configuration. Results further suggest that the presence of a gradual increase in mean sea level accelerates the initial morphological evolution of the system whose morphological rate of change gradually attains, however, same plateau values as in the absence of sea level rise. Given the same base morphology, increasing water levels enhance residual currents and the net transport near the coastline; and vice-versa, decreasing sea levels minimize both residuals and net transport near the coastline. The areas that are more affected by, water level and morphological changes, are the ones where the net transport is the highest. This manuscript explores and allows extending the idea of morphodynamic equilibrium at a regional scale, larger than the one for which this concept has been generally explored i.e., estuarine scale.


2019 ◽  
Author(s):  
Jaap H. Nienhuis ◽  
Jorge Lorenzo-Trueba

Abstract. Barrier islands are low-lying coastal landforms vulnerable to inundation and erosion by sea-level rise. Despite their socio-economic and ecological importance, their morphodynamic response to sea-level rise or other hazards is poorly understood. To tackle this knowledge gap, we outline and describe the BarrieR Inlet Environment (BRIE) model that can simulate long-term barrier morphodynamics. In addition to existing overwash and shoreface formulations, BRIE accounts for alongshore sediment transport, inlet dynamics, and flood-tidal delta deposition along barrier islands. Inlets within BRIE can open, close, migrate, merge with other inlets, and build flood-tidal delta deposits. Long-term simulations reveal complex emergent behaviour of tidal inlets resulting from interactions with sea-level rise, and overwash. BRIE also includes a stratigraphic module, which demonstrates that barrier dynamics under constant sea-level rise rates can result in stratigraphic profiles composed of inlet fill, flood-tidal delta and overwash deposits. In general, the BRIE model represents a process-based exploratory view of barrier island morphodynamics that can be used to investigate long-term risks of flooding and erosion in barrier environments. For example, BRIE can simulate barrier island drowning in cases where the imposed sea-level rise rate is faster than the morphodynamic response of the barrier island.


2015 ◽  
Vol 97 (1-2) ◽  
pp. 188-198 ◽  
Author(s):  
T.E. Baldock ◽  
A. Golshani ◽  
A. Atkinson ◽  
T. Shimamoto ◽  
S. Wu ◽  
...  

2018 ◽  
Vol 121 ◽  
pp. 1-8 ◽  
Author(s):  
Leicheng Guo ◽  
Matthew Brand ◽  
Brett F. Sanders ◽  
Efi Foufoula-Georgiou ◽  
Eric D. Stein

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