beyond the case study: characterizing natural floodplain heterogeneity in the United States

As river channels move across the valley floor, they create diverse topography including natural levees, cutoff meanders, secondary channels, and floodplain wetlands. These features increase the spatial heterogeneity of the floodplain. Many studies indicate that this heterogeneity strongly influences habitat abundance and diversity, storage of flood waters and excess nitrate or phosphate, and other floodplain functions. However, no one has systematically measured floodplain heterogeneity across multiple rivers and different geographic regions. We measured the heterogeneity of natural floodplains at 14 sites in the continental United States using metrics developed by landscape ecologists. We find that natural floodplains have distinctive heterogeneity signatures that relate to drainage area, the size of the floodplain, and other characteristics. The data included here are the original field data associated with 14 of the field sites, including GPS locations of floodplain transects, floodplain patches, sediment cores, and large wood; and delineated floodplain shapefiles.

Methods
The field data were collected along transects approximately evenly spaced and perpendicular to the valley trend with handheld Garmin GPS units (all locations), hand tapes (wood diameters), and hand-driven sediment corers (soil cores), except where noted explicitly in the data files. Dates of data collection and descriptions of classes identified visually in the field are included in each data file. The data documents areas of the floodplains that were accessible by car and foot at the time the data were collected and that time and resources allowed. The floodplain polygons were hand drawn in ArcGIS Pro using the field transect boundaries, digital elevation models (at least 10 m spatial resolution), Sentinel imagery, and park boundaries where applicable, and were generally drawn to exclude most of the human-impacted areas, but not all were excluded. Ten-meter geodesic buffers were added to most of the floodplain boundaries to account for field and/or user error (see specifics in README file).