Landsat imagery shows decline of coastal marshes in Chesapeake and Delaware Bays

Kearney, Michael; Rogers, A. S.; Townshend, J. R. G.; Rizzo, Eric; Stutzer, David; Stevenson, J. Court; Sundborg, Karen

doi:10.1029/2002eo000112

Cited by 120 publications

(113 citation statements)

References 7 publications

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“…[6] We use Landsat Thematic Mapper imagery in a spectral mixture model developed in studies of low salinity, microtidal marshes [Kearney et al, 2002], which was crossreferenced with comparisons from aerial photography to analyze changes in marsh vegetation cover and total marsh area since 1984 for these three diversions. The inherently wide geographic capture of changes afforded by high resolution satellite imagery provides a spatial and temporal perspective on the conflicting ideas about the efficacy of diversions to restore marsh.…”

Section: Introductionmentioning

confidence: 99%

Freshwater river diversions for marsh restoration in Louisiana: Twenty-six years of changing vegetative cover and marsh area

Kearney

Riter

Turner

2011

Geophys. Res. Lett.

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The restoration of Louisiana's coastal wetlands will be one of the largest, most costly and longest environmental remediation projects undertaken. We use Landsat data to show that freshwater diversions, a major restoration strategy, have not increased vegetation and marsh coverage in three freshwater diversions operating for ∼19 years. Two analytic methods indicate no significant changes in either relative vegetation or overall marsh area from 1984 to 2005 in zones closest to diversion inlets. After Hurricanes Katrina and Rita, these zones sustained dramatic and enduring losses in vegetation and overall marsh area, whereas the changes in similar marshes of the adjacent reference sites were relatively moderate and short‐lived. We suggest that this vulnerability to storm damage reflects the introduction of nutrients in the freshwater diversions (that add insignificant amounts of additional sediments), which promotes poor rhizome and root growth in marshes where below‐ground biomass historically played the dominant role in vertical accretion.

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Section: Introductionmentioning

confidence: 99%

Freshwater river diversions for marsh restoration in Louisiana: Twenty-six years of changing vegetative cover and marsh area

Kearney

Riter

Turner

2011

Geophys. Res. Lett.

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“…accretion ͉ erosion ͉ sea level ͉ vegetation ͉ wetland S ubsidence, erosion, sea-level rise, and anthropogenic changes to sediment delivery rates are affecting coastal marshes worldwide. In some regions these influences are converting significant portions of marshland to open water (1,2). The fate of intertidal salt marshes is of societal importance and scientific interest; marshes provide highly productive habitat and serve as nursery grounds for a large number of commercially important fin and shellfish (3,4).…”

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confidence: 99%

A coupled geomorphic and ecological model of tidal marsh evolution

Kirwan

Murray

2007

Proc. Natl. Acad. Sci. U.S.A.

457

433

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The evolution of tidal marsh platforms and interwoven channel networks cannot be addressed without treating the two-way interactions that link biological and physical processes. We have developed a 3D model of tidal marsh accretion and channel network development that couples physical sediment transport processes with vegetation biomass productivity. Tidal flow tends to cause erosion, whereas vegetation biomass, a function of bed surface depth below high tide, influences the rate of sediment deposition and slope-driven transport processes such as creek bank slumping. With a steady, moderate rise in sea level, the model builds a marsh platform and channel network with accretion rates everywhere equal to the rate of sea-level rise, meaning water depths and biological productivity remain temporally constant. An increase in the rate of sea-level rise, or a reduction in sediment supply, causes marsh-surface depths, biomass productivity, and deposition rates to increase while simultaneously causing the channel network to expand. Vegetation on the marsh platform can promote a metastable equilibrium where the platform maintains elevation relative to a rapidly rising sea level, although disturbance to vegetation could cause irreversible loss of marsh habitat. accretion ͉ erosion ͉ sea level ͉ vegetation ͉ wetland S ubsidence, erosion, sea-level rise, and anthropogenic changes to sediment delivery rates are affecting coastal marshes worldwide. In some regions these influences are converting significant portions of marshland to open water (1, 2). The fate of intertidal salt marshes is of societal importance and scientific interest; marshes provide highly productive habitat and serve as nursery grounds for a large number of commercially important fin and shellfish (3, 4). Additionally, marshes offer great value as buffers of coastal storms in cities such as New Orleans, which is separated from the Gulf of Mexico by marshland (5, 6).A variety of vertical accretion models have been used to address the response of tidal marshes to environmental change, including accelerated sea-level rise and reduced sediment supply (7,8). In these models, bed elevation of the marsh platform is adjusted according to a deposition rate that is proportional to water depth at high tide, a proxy for duration and frequency of inundation. In such models, an increase in the rate of sea-level rise is accompanied by an increase in water depth until the increasing deposition rate becomes equal to the sea-level rise rate. With the exception of recent work by Morris et al. (9), these models neglect the role of vegetation, despite Redfield's (10) hypothesis that vegetation and physical processes influence morphodynamics equally strongly in the intertidal zone. Vegetation traps inorganic sediment and provides a source of organic sediment. Based on field measurements, Morris et al. (9) argue that biomass density, and therefore deposition rates, increase with water depth up to some optimal depth. The role of biomass density in enhancing deposition rates in th...

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“…Human factors such as diking and impoundment (Weishar et al, 2005), conversion to cropland, pollution, channel dredging, and invasive species, have caused Delaware wetland area to decline by 54% since pre-colonial conditions (Dahl, 1990;Tiner et al, 2011), largely transitioning to open water or unconsolidated intertidal shoreline (Tiner et al, 2011). Kearney et al (2002) estimate that approximately 56% of the Delaware Estuary marshes are moderately to severely degraded.…”

Section: State Of Wetlands In the Delaware Estuarymentioning

confidence: 99%

“…Wetland areas are currently transitioning to open water, including interior ponds, which can accelerate with increasing rates of relative sea level rise (Kearney et al, 2002). Human factors such as diking and impoundment (Weishar et al, 2005), conversion to cropland, pollution, channel dredging, and invasive species, have caused Delaware wetland area to decline by 54% since pre-colonial conditions (Dahl, 1990;Tiner et al, 2011), largely transitioning to open water or unconsolidated intertidal shoreline (Tiner et al, 2011).…”

Section: State Of Wetlands In the Delaware Estuarymentioning

confidence: 99%

Modeling the Economic Value of Blue Carbon in Delaware Estuary Wetlands: Historic Estimates and Future Projections

Carr

Shirazi

Parsons

et al. 2018

Journal of Environmental Management

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Coastal wetlands sequester large amounts of carbon in their soils, effectively removing carbon dioxide from the atmosphere and acting as a carbon sink. In this paper, we estimate the economic value of carbon sequestered by wetlands in the Delaware Estuary. We estimate the value of the current stock of wetlands, the value of the historic loss of wetlands, and under a range of different scenarios the expected future loss. We use historical topographic maps and Land Cover inventories of the Delaware Estuary to measure the acreage of tidal wetlands in nine distinct time periods from 1778 to 2011. Using these data, we estimate an annual rate of wetland loss of 1.03km 2 . Coupling observed land cover change with exogenous factors including sea-level rise, population pressure, and channel dredging, we estimate changes in tidal wetland area under a range of future scenarios for our expected future economic loss estimates. Keywords carbon sequestration; blue carbon; tidal wetlands; ecosystem services; social cost of carbon 2

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Landsat imagery shows decline of coastal marshes in Chesapeake and Delaware Bays

Cited by 120 publications

References 7 publications

Freshwater river diversions for marsh restoration in Louisiana: Twenty-six years of changing vegetative cover and marsh area

Freshwater river diversions for marsh restoration in Louisiana: Twenty-six years of changing vegetative cover and marsh area

A coupled geomorphic and ecological model of tidal marsh evolution

Modeling the Economic Value of Blue Carbon in Delaware Estuary Wetlands: Historic Estimates and Future Projections

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