Mapping irregularly flooded wetlands, high marsh, and salt pannes/flats along the northern Gulf of Mexico coast (ver. 2.0, June 2023)

This data release includes geospatial data for irregularly flooded wetlands and high marsh and salt pannes/flats along the northern Gulf of Mexico coast from Texas to Florida. Specifically, this release includes seven products: (1) a map highlighting the continuous probability that an area is an irregularly flooded wetland; (2) a map of irregularly flooded wetland probability reclassified into four bins; (3) a map delineating high marsh and salt pannes/flats; (4) a map from Lake Pontchartrain, Louisiana to the Florida Big Bend delineating the coverage of irregularly flooded wetlands that have Juncus roemerianus (Black needlerush) as the dominant vegetation species; (5) a spatial metadata file showing what elevation data were used for specific locations; (6) a supplemental version of the high marsh and salt pannes/flats map that has a second class for high marsh for parts of Texas where succulents and Distichlis spicata were dominant species; and (7) a dataset of supplemental project-specific field reference data collected throughout the northern Gulf of Mexico coast.

Collectively, the products in this data release were developed using a two-step approach that utilized the best-available elevation data and satellite data from 2018 to 2020. The first step in the process was to create a probabilistic map of irregularly flooded wetlands using light detection and ranging (lidar)-derived digital elevation models (DEMs), tidal datums, and nuisance flooding levels. Monte Carlo simulations were used to propagate uncertainty in elevation-based data, and existing land cover data were used to restrict the output to coastal wetland areas. Due to the focus of this study on high marsh, these coastal wetland areas did not include tidal forested fresh wetlands. The second step was to delineate high marsh and salt pannes/flats using reference data which included project-specific data collection in collaboration with land managers and other ancillary datasets across the northern Gulf of Mexico coast. These data were combined with Sentinel-1 synthetic aperture radar imagery, multispectral optical satellite imagery from Sentinel-2, DEMs, and the irregularly flooded wetland probability layer to generate a contemporary map of high marsh and salt pannes/flats along the northern Gulf of Mexico coast. This product is the first regional map of these wetland systems across the northern Gulf of Mexico coast.