Elevation-based probabilistic mapping of irregularly flooded wetlands

Posted byChelsea KrossPosted inUncategorizedTags:,

A new paper from the Firebird High Marsh Mapping Team titled, “Elevation-based probabilistic mapping of irregularly flooded wetlands along the northern Gulf of Mexico coast” has been published in Remote Sensing of Environment. The primary objective of this study was to develop probabilistic maps for irregularly flooded wetlands along the northern Gulf of Mexico. While this work can address many needs, the key motivation for this effort was to produce a product that could be used to later develop a map of high marsh and salt pannes, which are found within the irregularly flooded wetland zone. The approach used coastal wetlands from existing land use/land cover data, best available lidar-derived digital elevation models, and Monte Carlo simulations to incorporate elevation uncertainty.

Irregularly flooded marsh at Cypremort Point State Park in Louisiana.

What do the results mean?

The output of this study was a probabilistic raster that was published as a USGS data release (Enwright et al., 2022). To quantify and explore differences in areal coverage along the northern Gulf of Mexico, the probability values in the map were classified into three equal bins (probability ≤0.33; probability >0.33 and ≤ 0.66; and probability >0.66). Wetlands in the lowest probability class (i.e., “unlikely”) were labelled as being in the upper (higher) or lower portion of the irregularly flooded wetland zone. This map product can serve many important applications including providing a baseline for gauging future coastal wetland transformation with climate change, mapping high marsh and salt pannes, and designing wetland vegetation and faunal monitoring programs.

Example of the irregularly flooded wetland probability output near Grand Bay, Mississippi, USA. a land cover map modified from the National Oceanic and Atmospheric Administration’s Coastal Change Analysis Program 30-m layer (NOAA, 2016). b irregularly flooded wetland probability on a continuous scale for areas within the coastal wetland mask. c irregularly flooded wetland probability by percent bin for areas within the coastal wetland mask. Unlikely and low, probability ≤0.33 and below mid-point between mean high water and the NOAA high-tide flooding level (Sweet et al., 2018); Unlikely and high, probability ≤0.33 and above mid-point between mean high water and the NOAA high-tide flooding level; Likely as not, probability >0.33 and ≤ 0.66; Likely, probability >0.66. (Figure is from Enwright et al., 2023)

Take Home Message

The framework developed in this study was used to produce an elevation-based probabilistic map of irregularly flooded wetlands. This product can be helpful for highlighting regional variability, teasing out high marsh and salt pannes, and tracking changes in the future due to sea-level rise.

Corresponding Author and Link to the Article
Nicholas Enwright, U.S. Geological Survey, Wetland and Aquatic Research Center, enwrightn@usgs.gov

https://doi.org/10.1016/j.rse.2023.113451

Literature Cited
Enwright, NM, WC Cheney, KO Evans, HR Thurman, MS Woodrey, AMV Fournier, DB Gesch, JL Pitchford, JM Stoker, and SC Medeiros. 2023. Elevation-based probabilistic mapping of irregularly flooded wetlands along the northern Gulf of Mexico coast. Remote Sensing of Environment, 287, 113451.

Enwright, NM, WC Cheney, K Evans, HR Thurman, MS Woodrey, AMV Fournier, A Bauer, J Cox, S Goehring, H Hill, K Hondrick, P Kappes, H Levy, J Moon, JA Nyman, J Pitchford, D Storey, M Sukiennik, and J Wilson. 2022. Mapping irregularly flooded wetlands, high marsh, and salt pannes/flats along the northern Gulf of Mexico coast: U.S. Geological Survey data release, https://doi.org/10.5066/P9MLO26U.

NOAA. 2016. NOAA’s Coastal Change Analysis Program (C-CAP) 2016 Regional Land Cover Change Data – Coastal United States [dataset]. https://coast.noaa.gov/htdata/raster1/landcover/bulkdownload/30m_lc/CCAP_Parent_2016.xml.

Sweet, WV, G Dusek, J Obeysekera, and JJ Marra. 2018. Patterns and Projections of High Tide Flooding Along the U.S. Coastline Using a Common Impact Threshold. NOAA Technical Report NOS CO-OPS 086. https://tidesandcurrents.noaa.gov/publications/techrpt86_PaP_of_HTFlooding.pdf.

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