“ChesBay 24k – LU": Land Use/Land Cover Related Data Summaries for the Chesapeake Bay Watershed Within NHD Plus HR catchments (ver. 2.0, October 2024)

These tabular data are summaries of land use/land cover related variables within catchments of the Chesapeake Bay watershed using the Xstrm methodology at 1:24,000 scale. Variables being counted as land use/land cover related contain all land use and land cover data including datasets that are split off or combined from those data (eg. agriculture or impervious classes only datasets). Outputs consist of tabular comma-separated values files (CSVs) 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. For information about the summarization process parameters, see xstrm_nhdhr_cbay_lulc_summary_expanded_metadata.csv.
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 network-connected 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 must be considered to provide adequate coverage of the summary catchments using this option. If an alternative 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.

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.