This dataset consists of raster geotiff outputs from modeling vertical accretion and carbon accumulation in the Nisqually River Delta, Washington, USA. These rasters represent projections of future habitat type, change in surface elevation above Mean Sea Level, and total sediment carbon accumulation since 2011 in coastal wetland habitats. Projections were generated in 20-year increments for 100 years for five amounts of sea-level rise, three amounts of suspended sediment concentrations, and two alternative configurations of the U.S. Interstate-5 causeway as it crosses the Nisqually River to either prevent or allow inland habitat migration (a total of 30 scenarios). The full methods and results are described in detail in the parent manuscript, “Can coastal habitats rise to the challenge? Resilience of estuarine habitats, carbon accumulation, and its value to sea-level rise for adaptation planning in a Puget Sound estuary” (2022).

This dataset consists of raster geotiff outputs from modeling vertical accretion and carbon accumulation in the Nisqually River Delta, Washington, USA. These rasters represent projections of future habitat type, change in surface elevation above Mean Sea Level, and total sediment carbon accumulation since 2011 in coastal wetland habitats. Projections were generated in 20-year increments for 100 years for five amounts of sea-level rise, three amounts of suspended sediment concentrations, and two alternative configurations of the U.S. Interstate-5 causeway as it crosses the Nisqually River to either prevent or allow inland habitat migration (a total of 30 scenarios). The full methods and results are described in detail in the parent manuscript, “Can coastal habitats rise to the challenge? Resilience of estuarine habitats, carbon accumulation, and its value to sea-level rise for adaptation planning in a Puget Sound estuary” (2022).

This dataset consists of raster geotiff outputs from modeling vertical accretion and carbon accumulation in the Nisqually River Delta, Washington, USA. These rasters represent projections of future habitat type, change in surface elevation above Mean Sea Level, and total sediment carbon accumulation since 2011 in coastal wetland habitats. Projections were generated in 20-year increments for 100 years for five amounts of sea-level rise, three amounts of suspended sediment concentrations, and two alternative configurations of the U.S. Interstate-5 causeway as it crosses the Nisqually River to either prevent or allow inland habitat migration (a total of 30 scenarios). The full methods and results are described in detail in the parent manuscript, “Can coastal habitats rise to the challenge? Resilience of estuarine habitats, carbon accumulation, and its value to sea-level rise for adaptation planning in a Puget Sound estuary” (2022).

This dataset provides the water content, bulk density, carbon concentrations, nitrogen concentrations, and carbon content of all fourteen cores sampled in coastal Louisiana (CRMS 0224) in October of 2019. Each sample is identified by a unique identifier that corresponds to each site by depth increment combination. The pond age range associated with each site is provided. The depth increment associated with each sample is provided.

This dataset provides maps of coastal wetland carbon and methane fluxes and coastal wetland surface elevation from 2006 to 2011 at 30 m resolution for coastal wetlands of the conterminous United States. Total coastal wetland carbon flux per year per pixel was calculated by combining maps of wetland type and change with soil, biomass, and methane flux data from a literature review. Uncertainty in carbon flux was estimated from 10,000 iterations of a Monte Carlo analysis. In addition to the uncertainty analysis, this dataset also provides a probabilistic map of the extent of tidal elevation, as well as the geospatial files used to create that surface, and a land cover and land cover change map of the coastal zone from 2006 to 2011 with accompanying estimated median soil, biomass, methane, and total CO2 equivalent annual fluxes, each with reported 95% confidence intervals, at 30 m resolution. Land cover was quantified using the Coastal Change Analysis Program (C-CAP), a Landsat-based land cover mapping product.

This data release contains land cover-derived statistics regarding estuarine vegetated wetland area change within estuary drainage areas along the conterminous U.S. This dataset includes net change in estuarine vegetated wetland area based on National Oceanic and Atmospheric Administration's (NOAA) Coastal Change Assessment Program (C-CAP) 1996 and 2016 land cover data. Net change was assessed between estuarine vegetated wetlands (i.e., estuarine marshes, mangroves, non-mangrove estuarine woody wetlands, and salt pannes, depending on vegetation coverage and type) and the following other landcover classes: 1) water; 2) unconsolidated shore; 3) freshwater woody wetlands; 4) freshwater marsh; 5) upland; and 6) agriculture. An estuarine vegetated wetland change scenario was assigned to each region depending on different combinations of positive and negative net change in some of these classes which describes how land building, transgression, or tidal restoration compare to estuarine vegetated wetland loss. This dataset also includes relative statistics of change compared to estuarine vegetated wetland and estuary area.

We used WARMER, a 1-D cohort model of wetland accretion (Swanson et al. 2014), which is based on Callaway et al. (1996), to examine SLR projections across each study site. Each cohort in the model represents the total organic and inorganic matter added to the soil column each year. WARMER calculates elevation changes relative to MSL based on projected changes in relative sea level, subsidence, inorganic sediment accumulation, aboveground and belowground organic matter productivity, compaction, and decay for a representative marsh area. Each cohort provides the mass of inorganic and organic matter accumulated at the surface in a single year as well as any subsequent belowground organic matter productivity (root growth) minus decay. Cohort density, a function of mineral, organic, and water content, is calculated at each time step to account for the decay of organic material and auto-compaction of the soil column. The change in relative elevation is then calculated as the difference between the change in modeled sea level and the change in height of the soil column, which was estimated as the sum of the volume of all cohorts over the unit area model domain. The total volume of an individual cohort is estimated as the sum of the mass of pore space water, sediment, and organic matter, divided by the cohort bulk density for each annual time step. Elevation is adjusted relative to sea level rise after each year of organic and inorganic input, compaction, and decomposition. We parameterized WARMER from the elevation, vegetation, and water level data collected at each site. We evaluated model outputs between 2010 and 2110 using marsh elevation zones defined above.Model inputs Sea-level rise scenariosIn WARMER, we incorporated a recent forecast for the Pacific coast which projects low, mid, and high SLR scenarios of 12, 64 and 142 cm by 2110, respectively (NRC 2012). We used the average annual SLR curve as the input function for the WARMER model. We assumed the difference between the maximum tidal height and minimum tidal height (tide range) remained constant through time, with only MSL changing annually.Inorganic matterThe annual sediment accretion rate is a function of inundation frequency and the mineral accumulation rates measured from 137Csdating of soil cores sampled across each site. For each site, we developed a continuous model of water level from the major harmonic constituents of a nearby NOAA tide gauge. This allowed a more accurate characterization of the full tidal regime as our water loggers were located above MLLW. Following Swanson et al. (2014), we assumed that inundation frequency was directly related to sediment mass accumulation; this simplifying assumption does not account for the potential feedback between biomass and sediment deposition and holds suspended sediment concentration and settling velocity constant. Sediment accretion, Ms,at a given elevation, z, is equal to, where f(z) is dimensionless inundation frequency as a function of elevation (z), and Sis the annual sediment accumulation rate in g cm-2 y-1.Organic matterWe used a unimodal functional shape to describe the relationship between elevation and organic matter (Morris et al. 2002), based on Atlantic coast work on Spartina alterniflora. Given that Pacific Northwest tidal marshes are dominated by other plant species, we developed site-specific, asymmetric unimodal relationships to characterize elevation-productivity relationships. We used Bezier curves to draw a unimodal parabola, anchored on the low elevation by MTL at the high elevation by the maximum observed water level from a nearby NOAA tide gauge. We determined the elevation of peak productivity by analyzing the Normalized Difference Vegetation Index (NDVI; (NIR - Red)/(NIR + Red)) from 2011 NAIP imagery (4 spectral bands, 1 m resolution; Tucker 1979) and our interpolated DEM. We then calibrated the amplitude of the unimodal function to the organic matter input rates (determined from sediment

We used WARMER, a 1-D cohort model of wetland accretion (Swanson et al. 2014), which is based on Callaway et al. (1996), to examine SLR projections across each study site. Each cohort in the model represents the total organic and inorganic matter added to the soil column each year. WARMER calculates elevation changes relative to MSL based on projected changes in relative sea level, subsidence, inorganic sediment accumulation, aboveground and belowground organic matter productivity, compaction, and decay for a representative marsh area. Each cohort provides the mass of inorganic and organic matter accumulated at the surface in a single year as well as any subsequent belowground organic matter productivity (root growth) minus decay. Cohort density, a function of mineral, organic, and water content, is calculated at each time step to account for the decay of organic material and auto-compaction of the soil column. The change in relative elevation is then calculated as the difference between the change in modeled sea level and the change in height of the soil column, which was estimated as the sum of the volume of all cohorts over the unit area model domain. The total volume of an individual cohort is estimated as the sum of the mass of pore space water, sediment, and organic matter, divided by the cohort bulk density for each annual time step. Elevation is adjusted relative to sea level rise after each year of organic and inorganic input, compaction, and decomposition. We parameterized WARMER from the elevation, vegetation, and water level data collected at each site. We evaluated model outputs between 2010 and 2110 using marsh elevation zones defined above.Model inputs Sea-level rise scenariosIn WARMER, we incorporated a recent forecast for the Pacific coast which projects low, mid, and high SLR scenarios of 12, 64 and 142 cm by 2110, respectively (NRC 2012). We used the average annual SLR curve as the input function for the WARMER model. We assumed the difference between the maximum tidal height and minimum tidal height (tide range) remained constant through time, with only MSL changing annually.Inorganic matterThe annual sediment accretion rate is a function of inundation frequency and the mineral accumulation rates measured from 137Csdating of soil cores sampled across each site. For each site, we developed a continuous model of water level from the major harmonic constituents of a nearby NOAA tide gauge. This allowed a more accurate characterization of the full tidal regime as our water loggers were located above MLLW. Following Swanson et al. (2014), we assumed that inundation frequency was directly related to sediment mass accumulation; this simplifying assumption does not account for the potential feedback between biomass and sediment deposition and holds suspended sediment concentration and settling velocity constant. Sediment accretion, Ms,at a given elevation, z, is equal to, where f(z) is dimensionless inundation frequency as a function of elevation (z), and Sis the annual sediment accumulation rate in g cm-2 y-1.Organic matterWe used a unimodal functional shape to describe the relationship between elevation and organic matter (Morris et al. 2002), based on Atlantic coast work on Spartina alterniflora. Given that Pacific Northwest tidal marshes are dominated by other plant species, we developed site-specific, asymmetric unimodal relationships to characterize elevation-productivity relationships. We used Bezier curves to draw a unimodal parabola, anchored on the low elevation by MTL at the high elevation by the maximum observed water level from a nearby NOAA tide gauge. We determined the elevation of peak productivity by analyzing the Normalized Difference Vegetation Index (NDVI; (NIR - Red)/(NIR + Red)) from 2011 NAIP imagery (4 spectral bands, 1 m resolution; Tucker 1979) and our interpolated DEM. We then calibrated the amplitude of the unimodal function to the organic matter input rates (determined from sediment

Healthy tidal marshes support the food webs that underpin our fisheries; they mitigate the impact of coastal storms, and they improve water quality. However, as sea level rises, marshes are at risk from “drowning.” To survive, marshes must maintain their elevation relative to surrounding waters. They do this, in part, through accretion, a process by which sediment suspended in the water accumulates on the marsh’s surface. For marshes to survive, accretion must keep pace with sea level rise. Making decisions to support marsh sustainability depends on the ability to accurately measure suspended sediment concentrations, yet current monitoring programs lack well-tested, effective approaches to doing so.

Coastal wetland ecosystems are expected to migrate landward in response to accelerated sea-level rise. However, due to differences in topography and coastal urbanization extent, estuaries vary in their ability to accommodate wetland migration. The landward movement of wetlands requires suitable conditions, such as a gradual slope and land free of urban development. Urban barriers can constrain migration and result in wetland loss (coastal squeeze). For future-focused conservation planning purposes, there is a pressing need to quantify and compare the potential for wetland landward movement and coastal squeeze. For 41 estuaries in the northern Gulf of Mexico (i.e., the USA gulf coast), we quantified and compared the area available for the landward migration of tidal saline wetlands and the area where urban development is expected to prevent migration (coastal squeeze), under three alternative future sea-level rise scenarios (0.5-, 1.0-, and 1.5-m by 2100).