Vertical Control of Rod Surface Elevation Table (RSET) Benchmarks to Assess Implications of Sea-Level Rise within Texas Coastal Refuges
The USGS will establish Rod Surface Elevation Tables at five National Wildlife Refuges on the Texas coast. This work will support climate adaptation and resilience planning by identifying areas susceptible to loss and degradation due to sea-level rise and extreme climatic events along the Texas Gulf Coast.
The Science Issue and Relevance: Coastal wetlands provide critical ecosystem services, making them one of the most valuable systems on the planet (Daily et al. 1997; Costanza et al. 2014). Ecologically, coastal wetlands store carbon, support fisheries, improve water quality, and provide wildlife habitat. Economically, they protect coastal communities and offer popular commercial and recreational opportunities (Barbier et al. 2011). Due to their inherent juxtaposition at the land-sea interface, coastal wetlands are threatened by multiple stressors induced by climate change (Gabler et al. 2017; Osland et al. 2018). Accelerated sea-level rise (Morris et al. 2002; Baustian et al. 2012) threatens the integrity of these vulnerable areas and the ecosystem services they provide. Maintaining and enhancing the ecological and economic contributions of coastal wetlands requires an advanced understanding of surface elevation dynamics, as these dynamics underpin the stability of these wetland ecosystems.
Coastal wetlands are resilient ecosystems that can build elevation to adjust to moderate levels of sea-level rise via positive feedbacks between inundation, plant growth, and sedimentation (Morris et el. 2002; Woodroffe et al. 2016). Higher rates of inundation and relative sea-level rise, however, can overwhelm the ability of coastal wetlands to build elevation, leading to a conversion to open water (i.e., wetland loss). Storm damages, sediment compaction, erosion, sediment starvation, changes in plant communities, and altered hydrology have prevented coastal marshes from building sufficient elevation to counteract the high rates of subsidence and relative sea-level rise they experience (Couvillion et al. 2017; Törnqvist et al. 2020). Parts of the Texas coast experience high rates of relative sea-level rise (Sweet et al. 2017), but the surface elevation change dynamics of coastal wetlands in Texas have not been extensively measured or studied.
Methodology for Addressing the Issue: The study area falls within five National Wildlife Refuges spanning an approximate 360-km section of the Texas coast: Aransas, San Bernard, Brazoria, Anahuac, and McFaddin (listed in geographic order from south to north; Fig. 1). Given the remoteness of the refuges, we will re-establish National Spatial Reference System (NSRS) connections at all study areas via static global positioning system (GPS) occupations and real-time kinematic positioning (RTK) surveys to improve model parameterization, calibration, and validation of rod surface elevation table (RSET) data.
Three RSET sites were established within each sample frame (refuge) in 2014 (Figs. 1 & 2). Within each site, three RSET rods (stations) were installed, with one rod serving as the primary control point (PCP) for each site. During each sampling effort, at each site, a static survey will be conducted atop the established PCP. Using RSET adapters, dual-frequency GPS receivers are attached to the RSET rod that will serve as the PCP. This allows for up to three concurrent static high precision GPS measurements within each sampling frame. The static GPS measurements will run continuously for at least four hours over each established PCP. A second set of static measurements will be taken the following day with a four-hour offset from the previous day’s sampling effort. These simultaneous occupations will allow for the use of Online Positioning User Service-Projects (OPUS) to provide a network adjustment (correction value) to the GPS observations.
Future Steps: The project will support climate adaptation and resilience planning by identifying areas susceptible to loss and degradation due to sea-level rise and extreme climatic events along the Texas Gulf Coast. Further, this project will provide the capacity to improve some current predictive climate models, such as the Sea Level Affecting Marshes Model (SLAMM), by improving and refining parameter estimates.
The USGS will establish Rod Surface Elevation Tables at five National Wildlife Refuges on the Texas coast. This work will support climate adaptation and resilience planning by identifying areas susceptible to loss and degradation due to sea-level rise and extreme climatic events along the Texas Gulf Coast.
The Science Issue and Relevance: Coastal wetlands provide critical ecosystem services, making them one of the most valuable systems on the planet (Daily et al. 1997; Costanza et al. 2014). Ecologically, coastal wetlands store carbon, support fisheries, improve water quality, and provide wildlife habitat. Economically, they protect coastal communities and offer popular commercial and recreational opportunities (Barbier et al. 2011). Due to their inherent juxtaposition at the land-sea interface, coastal wetlands are threatened by multiple stressors induced by climate change (Gabler et al. 2017; Osland et al. 2018). Accelerated sea-level rise (Morris et al. 2002; Baustian et al. 2012) threatens the integrity of these vulnerable areas and the ecosystem services they provide. Maintaining and enhancing the ecological and economic contributions of coastal wetlands requires an advanced understanding of surface elevation dynamics, as these dynamics underpin the stability of these wetland ecosystems.
Coastal wetlands are resilient ecosystems that can build elevation to adjust to moderate levels of sea-level rise via positive feedbacks between inundation, plant growth, and sedimentation (Morris et el. 2002; Woodroffe et al. 2016). Higher rates of inundation and relative sea-level rise, however, can overwhelm the ability of coastal wetlands to build elevation, leading to a conversion to open water (i.e., wetland loss). Storm damages, sediment compaction, erosion, sediment starvation, changes in plant communities, and altered hydrology have prevented coastal marshes from building sufficient elevation to counteract the high rates of subsidence and relative sea-level rise they experience (Couvillion et al. 2017; Törnqvist et al. 2020). Parts of the Texas coast experience high rates of relative sea-level rise (Sweet et al. 2017), but the surface elevation change dynamics of coastal wetlands in Texas have not been extensively measured or studied.
Methodology for Addressing the Issue: The study area falls within five National Wildlife Refuges spanning an approximate 360-km section of the Texas coast: Aransas, San Bernard, Brazoria, Anahuac, and McFaddin (listed in geographic order from south to north; Fig. 1). Given the remoteness of the refuges, we will re-establish National Spatial Reference System (NSRS) connections at all study areas via static global positioning system (GPS) occupations and real-time kinematic positioning (RTK) surveys to improve model parameterization, calibration, and validation of rod surface elevation table (RSET) data.
Three RSET sites were established within each sample frame (refuge) in 2014 (Figs. 1 & 2). Within each site, three RSET rods (stations) were installed, with one rod serving as the primary control point (PCP) for each site. During each sampling effort, at each site, a static survey will be conducted atop the established PCP. Using RSET adapters, dual-frequency GPS receivers are attached to the RSET rod that will serve as the PCP. This allows for up to three concurrent static high precision GPS measurements within each sampling frame. The static GPS measurements will run continuously for at least four hours over each established PCP. A second set of static measurements will be taken the following day with a four-hour offset from the previous day’s sampling effort. These simultaneous occupations will allow for the use of Online Positioning User Service-Projects (OPUS) to provide a network adjustment (correction value) to the GPS observations.
Future Steps: The project will support climate adaptation and resilience planning by identifying areas susceptible to loss and degradation due to sea-level rise and extreme climatic events along the Texas Gulf Coast. Further, this project will provide the capacity to improve some current predictive climate models, such as the Sea Level Affecting Marshes Model (SLAMM), by improving and refining parameter estimates.