“ChesBay 24k – LU": Land Use/Land Cover Related Data Summaries for the Chesapeake Bay Watershed Within NHD Plus HR catchments (ver. 3.0, August 2025)

These tabular data are the summarization of land use/land cover related variables within the Chesapeake Bay watershed using the xstrm methodology bringing these data to the 1:24,000 scale. Variables being counted as land use/land cover related include all land use and land cover data. This also contains datasets that are split off or combined from source data (eg. agriculture or impervious only datasets combined from agriculture or impervious land use/land cover classes). Outputs consist of tabular comma-separated values files (CSVs), and parquet formatted files for both the local catchment and network summaries linked to the National Hydrography Dataset Plus High-Resolution (NHDPlus HR) framework by NHDPlus ID. Local catchments are defined as the single catchment the data is summarized within. Network accumulation summaries were completed for each of these catchments and their respective upstream catchments. The summarized data tables are structured as a single column representing the catchment id values (ie. nhdplusid) and the remaining columns consisting of the summarized variables. The downstream network summary type is not present within the dataset as no summaries were conducted using that summary type. Additionally, for a full description of the variables included within these summaries see xstrm_nhdhr_lulc_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" (hereafter referred to as catchment(s)), 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 and given computing power limitations. 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 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_lulc_chesapeake_baywide_versionhistory.txt. 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.