High-resolution mapping of biomass and distribution of marsh and forested wetlands in southeastern coastal Louisiana

Thomas, Nathan; Simard, Marc; Castañeda‐Moya, Edward; Byrd, Kristin B.; Windham‐Myers, Lisamarie; Bevington, A.; Twilley, Robert R.

doi:10.1016/j.jag.2019.03.013

Cited by 28 publications

(31 citation statements)

References 40 publications

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“…Other studies have assessed AGB in the broader MDP [6,29], including the Atchafalaya basin, though these studies employ coarser satellite data that is not as well suited for local-scale sites such as the WLD. For example, Byrd et al [29] use Landsat and Sentinel-1 data to model herbaceous marsh biomass in seven coastal wetland regions throughout the conterminous United States, of which the MDP is one.…”

Section: Discussionmentioning

confidence: 99%

“…Further, the study [25] is not limited to emergent vegetation and includes the deltaic island interiors (i.e., interdistributary bays) where floating vegetation is prominent, which may appear very bright in optical data (Figure 1) and lead to erroneous higher AGB estimates. In addition, Thomas et al [6] use an in situ AGB dataset for both herbaceous and forested wetland vegetation in the study area, which overlaps with the data used in this study, reporting a mean sample AGB density of 3.82 Mg/ha for herbaceous wetlands and 227.02 Mg/ha for forested wetlands in May of 2015. Thomas et al [6], however, could not devise a robust model from coincident Sentinel-1 and Sentinel-2 data with the number of field sites available.…”

Section: Discussionmentioning

confidence: 99%

“…Vegetation biomass contributes to several ecosystem processes with feedbacks including nutrient allocation, sedimentation and accretion rates, riverine and tidal inundation, and weather patterns [1][2][3][4]. Estimation and monitoring of wetland biomass, or "blue carbon," are needed to assess a wetland's ability to trap exogenic sediment and produce organic soils that increase surface elevation relative to sea level rise [5,6]. Accurate AGB maps can be used to analyze and predict changes in wetland vegetation cover and total carbon storage [2,7,8], and accordingly understand its impact on landscape and hydrological processes [9].…”

Section: Introductionmentioning

confidence: 99%

“…A better understanding of biomass stocks and distributions in these prograding deltaic wetland areas may inform future restoration efforts. AGB has been examined in the Wax Lake Delta (WLD), but as part of a broader national-scale assessment of carbon stocks using satellite data that did not resolve the local-scale AGB distributions in the WLD [29,35] or as part of a regional-scale AGB assessment that could not find a robust relationship with available in situ and satellite data [6]. This study's primary objective, then, is to develop an integrated empirical approach for estimating AGB that leverages the unique capabilities provided by each data type collected in tandem by airborne instruments.…”

Section: Introductionmentioning

confidence: 99%

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Integrating Imaging Spectrometer and Synthetic Aperture Radar Data for Estimating Wetland Vegetation Aboveground Biomass in Coastal Louisiana

et al. 2019

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Aboveground biomass (AGB) plays a critical functional role in coastal wetland ecosystem stability, with high biomass vegetation contributing to organic matter production, sediment accretion potential, and the surface elevation’s ability to keep pace with relative sea level rise. Many remote sensing studies have employed either imaging spectrometer or synthetic aperture radar (SAR) for AGB estimation in various environments for assessing ecosystem health and carbon storage. This study leverages airborne data from NASA’s Airborne Visible/Infrared Imaging Spectrometer-Next Generation (AVIRIS-NG) and Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) to assess their unique capabilities in combination to estimate AGB in coastal deltaic wetlands. Here we develop AGB models for emergent herbaceous and forested wetland vegetation in coastal Louisiana. In addition to horizontally emitted, vertically received (HV) backscatter, SAR parameters are expressed by the Freeman–Durden polarimetric decomposition components representing volume and double-bounce scattering. The imaging spectrometer parameters include normalized difference vegetation index (NDVI), reflectance from 290 visible-shortwave infrared (VSWIR) bands, the first derivatives from those bands, or partial least squares (PLS) x-scores derived from those data. Model metrics and cross-validation indicate that the integrated models using the Freeman-Durden components and PLS x-scores improve AGB estimates for both wetland vegetation types. In our study domain over Louisiana’s Wax Lake Delta (WLD), we estimated a mean herbaceous wetland AGB of 3.58 Megagrams/hectare (Mg/ha) and a total of 3551.31 Mg over 9.92 km2, and a mean forested wetland AGB of 294.78 Mg/ha and a total of 27,499.14 Mg over 0.93 km2. While the addition of SAR-derived values to imaging spectrometer data provides a nominal error decrease for herbaceous wetland AGB, this combination significantly improves forested wetland AGB prediction. This integrative approach is particularly effective in forested wetlands as canopy-level biochemical characteristics are captured by the imaging spectrometer in addition to the variable structural information measured by the SAR.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Integrating Imaging Spectrometer and Synthetic Aperture Radar Data for Estimating Wetland Vegetation Aboveground Biomass in Coastal Louisiana

et al. 2019

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“…The digital camera can be used to map the extents of surface water in cloud-free conditions (e.g., [37]). In this study the camera was not installed, and instead, we used a pre-existing land cover mask generated from Sentinel-2 data by Thomas et al [38] to delineate land and water.…”

Section: Airswot Overviewmentioning

confidence: 99%

Mapping Water Surface Elevation and Slope in the Mississippi River Delta Using the AirSWOT Ka-Band Interferometric Synthetic Aperture Radar

et al. 2019

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AirSWOT is an airborne Ka-band synthetic aperture radar, capable of mapping water surface elevation (WSE) and water surface slope (WSS) using single-pass interferometry. AirSWOT was designed as a calibration and validation instrument for the forthcoming Surface Water and Ocean Topography (SWOT) mission, an international spaceborne synthetic aperture radar mission planned for launch in 2022 which will enable global mapping of WSE and WSS. As an airborne instrument, capable of quickly repeating overflights, AirSWOT enables measurement of high frequency and fine scale hydrological processes encountered in coastal regions. In this paper, we use data collected by AirSWOT in the Mississippi River Delta and surrounding wetlands of coastal Louisiana, USA, to investigate the capabilities of Ka-band interferometry for mapping WSE and WSS in coastal marsh environments. We introduce a data-driven method to estimate the time-varying interferometric phase drift resulting from radar hardware response to environmental conditions. A system of linear equations based on AirSWOT measurements is solved for elevation bias and time-varying phase calibration parameters using weighted least squares. We observed AirSWOT WSE uncertainty of 12 cm RMS compared to in situ water level measurements when averaged over an area of 0.5 km 2 at incidence angles below 15 ∘ . At higher incidence angles, the observed AirSWOT elevation bias is possibly due to residual phase calibration errors or radar backscatter from vegetation. Elevation profiles along the Wax Lake Outlet river channel indicate AirSWOT can measure WSS over a 24 km distance with uncertainty below 0.3 cm/km, 8% of the true water surface slope as measured by in situ data. The data analysis and results presented in this paper demonstrate the potential of AirSWOT to measure water surface elevation and slope within highly dynamic and spatially complex coastal environments.

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Observation of the Coastal Areas, Estuaries and Deltas from Space

et al. 2023

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Coastal regions (including estuaries and deltas) are very complex environments with diverse hydrodynamic and bio-geomorphological contexts and with important socio-economic and ecological problems. These systems are among the most affected by human impact through urbanization and port activities, industrial and tourism activities. They are directly affected by the impact of climate change on sea level, storm surges frequency and strength, as well as recurrence of coastal river floods. A sustainable future for coastal zones depends on our capacity to implement systematic monitoring with focus on: (1) forcings affecting coastal zones at different spatio-temporal scales (sea level rise, winds and waves, offshore and coastal currents, tides, storm surges, river runoff in estuaries and deltas, sediment supply and transport, vertical land motions and land use); (2) morphological response (e.g., shoreline migration, topographical changes). Over the last decades, remote sensing observations have contributed to major advances in our understanding of coastal dynamics. This paper provides an overview of these major advances to measure the main physical parameters for monitoring the coastal, estuarine and delta environments and their evolution, such as the water level and hydrodynamics near the shoreline, water/sediment contact (i.e., shoreline), shoreline position, topography, bathymetry, vertical land motion, bio-physical characteristics of sediments, water content, suspended sediment, vegetation, and land use and land cover.

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High-resolution mapping of biomass and distribution of marsh and forested wetlands in southeastern coastal Louisiana

Cited by 28 publications

References 40 publications

Integrating Imaging Spectrometer and Synthetic Aperture Radar Data for Estimating Wetland Vegetation Aboveground Biomass in Coastal Louisiana

Integrating Imaging Spectrometer and Synthetic Aperture Radar Data for Estimating Wetland Vegetation Aboveground Biomass in Coastal Louisiana

Mapping Water Surface Elevation and Slope in the Mississippi River Delta Using the AirSWOT Ka-Band Interferometric Synthetic Aperture Radar

Observation of the Coastal Areas, Estuaries and Deltas from Space

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