“ChesBay 24k – NE": Natural Environment Related Data Summaries for the Chesapeake Bay Watershed Within NHD Plus HR catchments (ver. 4.0, August 2025)

These tabular data are the summarization of natural environment related variables within catchments of the Chesapeake Bay watershed at the 1:24,000 scale using the xstrm methodology. Variables being counted as natural environment related include soils/geology, lithology, elevation, slope, stream gradient, landform (geomorphon) and others. Outputs include tabular comma-separated values files (CSVs) and parquet files for the local catchment and network summaries linked to the National Hydrography Dataset Plus High-Resolution (NHDPlus HR) catchments by NHDPlus ID. Local catchments are defined as the single catchment within which the data are summarized. Network summaries are summaries for each of the local catchments and their respective network-connected upstream catchments for select variables. The summarized data tables are structured as a single column representing the catchment id values (ie. NHDPlus ID) and the remaining columns consisting of the summarized variables. Xstrm downstream network summaries are not present within this dataset as no summaries were conducted using that network summary method. For a full description of the variables included within these summaries see xstrm_nhdhr_natural_chesapeake_baywide_datadictionary.csv in the attached files. The xstrm local summary methodology takes either raster or point data as input then summarizes those data by "zones", in this case the NHDPlus HR catchments. The network summaries then take the results from the local summaries and calculates the desired network summary statistic for the local catchment and its respective upstream or downstream catchments. As a note concerning use of these data, any rasters summarized within this process only had their cells included within a catchment if the center of the raster cell fell within the catchment boundary. However, the resolution of the input raster data for these summaries was considered to provide completely adequate coverage of the summary catchments using this option. If a confirmed complete coverage of a catchment is desired (even if a raster cell only is minimally included within the catchment) then it is recommended to rerun the xstrm summary process with the "All Touched" option set to “True”. These data were updated in September 2024, March 2025, and August 2025. Some changes during these revisions include the removal of several variables unnecessary to the use of the data summaries, correction of incorrectly calculated area variables and all dependent variables, and the addition of several new variables. For a full list of changes see, xstrm_nhdhr_natural_chesapeake_baywide_versionhistory.txt. Also to note, if using R readr package read_csv function please set the guess_max parameter to 20,000 or higher. The nhdhr_underground_conduit_percent_length and nhdhr_drainageway_percent_length variables have a high number of NA values present which results in a blank column due to an error of the function's column type guess. Further information on the Xstrm summary process can be found at the Xstrm software release pages: Xstrm: Wieferich, D.J., Williams, B., Falgout, J.T., Foks, N.L. 2021. xstrm. U.S. Geological Survey software release. https://doi.org/10.5066/P9P8P7Z0. Xstrm Local: Wieferich, D.J., Gressler B., Krause K., Wieczorek M., McDonald, S. 2022. xstrm_local Version-1.1.0. U.S. Geological Survey software release. https://doi.org/10.5066/P98BOGI9.

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