Wave attenuation across a tidal marsh in San Francisco Bay

Foster‐Martinez, Madeline R.; Lacy, Jessica R.; Ferner, Matthew C.; Variano, Evan

doi:10.1016/j.coastaleng.2018.02.001

Cited by 39 publications

(26 citation statements)

References 43 publications

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“…A narrow transition zone with mixed vegetation lies between the cordgrass and pickleweed zones. Vegetation data collected during the study showed that in winter, cordgrass lost most of its above‐ground biomass, with decreased stem density, half the stem width, and one third the height compared to summer (Foster‐Martinez et al, ). Pickleweed, which is more shrub‐like and does not bear leaves, retained stem density and height between the seasons.…”

Section: Methodsmentioning

confidence: 99%

“…The vegetation in the China Camp marsh is strongly controlled by elevation. Spartina foliosa (cordgrass) occupies the lower marsh, in an approximately 40‐m wide band adjacent to the mudflats, at elevations of 0.77–1.47 m NAVD88 (Baye, ; Foster‐Martinez et al, ). Most of the marsh is above the mean high water (MHW) elevation of 1.68 m NAVD88, and is vegetated almost entirely by Salicornia pacifica (pickleweed).…”

Section: Methodsmentioning

confidence: 99%

“…We assess sediment supply across the bay-marsh interface and its variation with season and wave energy from the difference between flood-and ebb-tide SSC and from spatial gradients in estimated suspended-sediment flux, and compare to accretion measurements. This paper builds on previous work at this site, which investigated wave attenuation at the marsh edge and temporal variation in sediment flux in tidal creeks (Foster-Martinez et al, 2018;Lacy et al, 2018).…”

Section: Introductionmentioning

confidence: 96%

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Seasonal Variation in Sediment Delivery Across the Bay‐Marsh Interface of an Estuarine Salt Marsh

et al. 2020

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Sediment transport across bay-marsh interfaces depends on wave energy, vegetation, and marsh-edge morphology and varies over a range of timescales. We investigated these dynamics in a tidal salt marsh with a gently sloped, vegetated edge adjacent to northern San Francisco Bay. Spartina foliosa (cordgrass) inhabits the lower marsh and Salicornia pacifica (pickleweed) predominates on the marsh plain. We measured suspended-sediment concentration (SSC) and hydrodynamics in bay shallows and along a 100-m cross-shore transect in the marsh, during winter and summer. Four-year averaged accretion measured with marker-horizon plots was twice as great along the marsh transect as adjacent to a tidal creek, 50 m from the bay. We estimated deposition and trapping efficiency from the time series data to assess its variation with season and wave energy. At high tide the transition zone (between cordgrass and pickleweed) was usually erosional, the pickleweed zone was depositional, and both erosion and deposition increased with wave energy, as did the landward position of maximum deposition. Erosion from the transition zone accounted for approximately one third of the sediment flux into the pickleweed. In the pickleweed zone, SSC, the difference between flood-and ebb-tide SSC, and trapping efficiency were greater in summer than winter for comparable wave conditions, which we attribute to increased sediment trapping by dense summer cordgrass. Moderate waves in summer (46%) accounted for more annual accretion in the pickleweed zone than larger waves in winter (28%), although the contribution of winter storms was diminished by the dry winter during the study.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

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Seasonal Variation in Sediment Delivery Across the Bay‐Marsh Interface of an Estuarine Salt Marsh

et al. 2020

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“…Research has shown that marshes play an essential role in protecting shorelines and other coastal assets by increasing bottom friction and dissipating waves [ 32 – 37 ]. Specifically, their along- and cross-shore extents, productivity (biomass density), and bathymetry influence their ability to attenuate storm surge and waves [ 3 , 38 , 39 ].…”

Section: Introductionmentioning

confidence: 99%

Dynamic responses and implications to coastal wetlands and the surrounding regions under sea level rise

et al. 2018

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Two distinct microtidal estuarine systems were assessed to advance the understanding of the coastal dynamics of sea level rise in salt marshes. A coupled hydrodynamic-marsh model (Hydro-MEM) was applied to both a marine-dominated (Grand Bay, Mississippi) and a mixed fluvial/marine (Weeks Bay, Alabama) system to compute marsh productivity, marsh migration, and potential tidal inundation from the year 2000 to 2100 under four sea level rise scenarios. Characteristics of the estuaries such as geometry, sediment availability, and topography, were compared to understand their role in the dynamic response to sea level rise. The results show that the low sea level rise scenario (20 cm) approximately doubled high-productivity marsh coverage in the marine-dominated estuary by the year 2100 due to an equilibrium between the rates of sea level rise and marsh platform accretion. Under intermediate-low sea level rise (50 cm), high-productivity marsh coverage in the year 2100 increased (doubled in the marine-dominated estuary and a seven-fold increase in the mixed estuary) by expanding into higher lands followed by the creation of interior ponds. The results also indicate that marine-dominated estuaries are vulnerable to collapse as a result of low, relatively uniform topography and lack of sediment sources, whereas mixed estuaries are able to expand due to higher elevations and sediment inputs. The results from the higher sea level rise scenarios (the intermediate-high (120 cm) and high (200 cm)) showed expansion of the bays along with marsh migration to higher land, producing a five-fold increase in wetland coverage for the mixed estuary and virtually no net change for the marine-dominated estuary. Additionally, hurricane storm surge simulations showed that under higher sea level rise scenarios, the marine-dominated estuary demonstrated weaker peak stage attenuation indicating that the marsh’s ability to dissipate storm surge is sensitive to productivity changes and bay expansion / marsh loss.

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“…Vuik [23,47] showed that the capacity of marshes to attenuate waves is hampered by the breaking of stems under high wave loads. Moreover, field studies have consistently shown that the wave dampening capacity diminishes when the marsh is considerably inundated [16,48,49]. Well-known models of wave dampening by vegetation predict a continuously stronger decrease in drag-force from vegetation as the inundation depth exceeds the height of the vegetation [50][51][52].…”

Section: Flood Protection Services By Marshesmentioning

confidence: 99%

The Sensitivity of a Dike-Marsh System to Sea-Level Rise—A Model-Based Exploration

Marijnissen

Kok

Kroeze

et al. 2020

JMSE

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Integrating natural components in flood defence infrastructure can add resilience to sea-level rise. Natural foreshores can keep pace with sea-level rise by accumulating sediment and attenuate waves before reaching the adjacent flood defences. In this study we address how natural foreshores affect the future need for dike heightening. A simplified model of vertical marsh accretion was combined with a wave model and a probabilistic evaluation of dike failure by overtopping. The sensitivity of a marsh-dike system was evaluated in relation to a combination of processes: (1) sea-level rise, (2) changes in sediment concentration, (3) a retreat of the marsh edge, and (4) compaction of the marsh. Results indicate that foreshore processes considerably affect the need for dike heightening in the future. At a low sea-level rise rate, the marshes can accrete such that dike heightening is partially mitigated. But with sea-level rise accelerating, a threshold is reached where dike heightening needs to compensate for the loss of marshes, and for increasing water levels. The level of the threshold depends mostly on the delivery of sediment and degree of compaction on the marsh; with sufficient width of the marsh, lateral erosion only has a minor effect. The study shows how processes and practices that hamper or enhance marsh development today exacerbate or alleviate the challenge of flood protection posed by accelerated sea-level rise.

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Wave attenuation across a tidal marsh in San Francisco Bay

Cited by 39 publications

References 43 publications

Seasonal Variation in Sediment Delivery Across the Bay‐Marsh Interface of an Estuarine Salt Marsh

Seasonal Variation in Sediment Delivery Across the Bay‐Marsh Interface of an Estuarine Salt Marsh

Dynamic responses and implications to coastal wetlands and the surrounding regions under sea level rise

The Sensitivity of a Dike-Marsh System to Sea-Level Rise—A Model-Based Exploration

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