This data set has been superseded by huc2m. This file contains hydrologic unit boundaries and codes for the conterminous United States along with Alaska, Hawaii, Puerto Rico and the U.S. Virgin Islands. It was revised for inclusion in the National Atlas of the United States of America, and updated to match the streams file created by the USGS National Mapping Division (NMD) for the National Atlas of the United States of America. For the most current data and information relating to hydrologic unit codes (HUCs) please see http://water.usgs.gov/GIS/huc.html. The Watershed Boundary Dataset (WBD) is the most current data available for watershed delineation. See http://www.nrcs.usda.gov/wps/portal/nrcs/main/national/water/watersheds/dataset

This file contains hydrologic unit boundaries and codes for the conterminous United States along with Alaska, Hawaii, Puerto Rico and the U.S. Virgin Islands. It was revised for inclusion in the National Atlas of the United States of America, and updated to match the streams file created by the USGS National Mapping Division (NMD) for the National Atlas of the United States of America. For the most current data and information relating to hydrologic unit codes (HUCs) please see http://water.usgs.gov/GIS/huc.html. The Watershed Boundary Dataset (WBD) is the most current data available for watershed delineation. See http://www.nrcs.usda.gov/wps/portal/nrcs/main/national/water/watersheds/dataset

This file contains hydrologic unit boundaries and codes for the conterminous United States along with Alaska, Hawaii, Puerto Rico and the U.S. Virgin Islands. It was revised for inclusion in the National Atlas of the United States of America, and updated to match the streams file created by the USGS National Mapping Division (NMD) for the National Atlas of the United States of America. For the most current data and information relating to hydrologic unit codes (HUCs) please see http://water.usgs.gov/GIS/huc.html. The Watershed Boundary Dataset (WBD) is the most current data available for watershed delineation. See http://www.nrcs.usda.gov/wps/portal/nrcs/main/national/water/watersheds/dataset

The Geographic Information Retrieval and Analysis System (GIRAS) was developed in the mid 70s to put into digital form a number of data layers which were of interest to the USGS. One of these data layers was the Hydrologic Units. The map is based on the Hydrologic Unit Maps published by the U.S. Geological Survey Office of Water Data Coordination, together with the list descriptions and name of region, subregion, accounting units, and cataloging unit. The hydrologic units are encoded with an eight- digit number that indicates the hydrologic region (first two digits), hydrologic subregion (second two digits), accounting unit (third two digits), and cataloging unit (fourth two digits). The data produced by GIRAS was originally collected at a scale of 1:250K. Some areas, notably major cities in the west, were recompiled at a scale of 1:100K. In order to join the data together and use the data in a geographic information system (GIS) the data were processed in the ARC/INFO GUS software package. Within the GIS, the data were edgematched and the neatline boundaries between maps were removed to create a single data set for the conterminous United States. NOTE: A version of this data theme that is more throughly checked (though based on smaller-scale maps) is available here: https://water.usgs.gov/lookup/getspatial?huc2m HUC, GIRAS, Hydrologic Units, 1:250 For the most current data and information relating to hydrologic unit codes (HUCs) please see http://water.usgs.gov/GIS/huc.html. The Watershed Boundary Dataset (WBD) is the most current data available for watershed delineation. See http://www.nrcs.usda.gov/wps/portal/nrcs/main/national/water/watersheds/dataset

The Geospatial Fabric is a dataset of spatial modeling units for use within the National Hydrologic Model that covers Alaska, and most major river basins that flow in from Canada. This U.S. Geological Survey (USGS) data release consists of the geospatial fabric features and other related datasets created to expand the National Hydrologic Model to Alaska. This U.S. Geological Survey (USGS) child item consists of 17 different spatial layers in GeoTIFF format for Alaska. They are 1) average water capacity (awc.zip), 2) percent sand (sand.zip), 3) percent silt (silt.zip), 4) percent clay (clay.zip), 5) soil texture (TEXT_PRMS.zip), 6) land use/land cover (LULC.zip), 7) snow values (snow.zip), 8) summer rain values (SRain.zip), 9) winter rain values (WRain.zip), 10) leaf presence values (keep.zip), 11) leaf loss values (loss.zip), 12) percent tree canopy (CNPY.zip), 13) percent impervious surface (imperv.zip), 14) snow depletion curve numbers (CV_INT.zip), 15) rooting depth (RootDepth.zip), 16) permeability values (Lithology_exp_Konly_Project.zip), and 17) water bodies (wbg.zip). All data cover the National Hydrologic Model's (NHM) Alaskan domain. The 250-meter (m) raster datasets for soils (in sand.zip, silt.zip, clay.zip, TEXT_PRMS.zip) are derived from the Zonodo data (Hengl, 2018). The 30-meter raster of land use and land cover data are a simplified re-classification version of the North American Land-Change Monitoring System (NALCMS, Latifovic and others, 2012) data following the guidance and crosswalk table (crosswalk.csv) in Viger and Leavesley (2007). This layer was used to derive rasters representing dominant vegetative cover type, snow, summer and winter rain interception values, leaf cover and loss, and rooting depth. The impervious data were compiled from the Global Man-made Impervious Surface (GMIS) Dataset from Landsat, v1 (Brown de Colstoun, 2010). The tree canopy data were compiled from MOD44B MODIS/Terra Vegetation Continuous Fields Yearly L3 Global 250m SIN Grid V006, (Sexton and others, 2013). The snow depletion data was compiled from data by Liston (2009) and further processed using methods provided in a snow depletion table (SDC_table.csv) by Sexstone and others (2020). All file formats are in GeoTIFF (Geograhpic Tagged Imaged Format).

This data release consists of a comma-delimited ascii file with attributes for 21 U.S. Geological Survey streamgage sites in Hawai‘i and Southeast Alaska selected to enable assessment of how floods might change in a future climate. Floods in Hawai‘i and Southeast Alaska have led to loss of human life; damage to agricultural crops, cultural and biological resources, infrastructure, and property; threats to public health; and conditions that are highly disruptive to residents and visitors. Floods are generated by atmospheric and terrestrial processes that may be enhanced or depressed in response to climate change. Understanding the mechanisms that generate floods can be useful for assessing how floods may change in future climates and developing adaptive-management strategies to cope with future floods. Key to improved understanding of floods in Hawai‘i and Southeast Alaska is identifying sites that are affected by known flood-generating mechanisms and that can be used to potentially assess the effects of these mechanisms on the magnitude and frequency of floods, both historically and in a future climate. Stakeholders representing scientific, public-safety, cultural, and ecologic perspectives from government, academic, and private institutions provided input for developing and refining site-selection criteria and selecting sites. The site-selection criteria were: (1) the site contributes to representing the primary flood-generating mechanisms in the study area, (2) the site's available annual peak-streamflow record contains a minimum of 10 years of record during the 1980-2020 period, with a preference for longer records, (3) streamflow at the site during 1980-2020 was not substantively affected by regulation, urban areas, and basin land-use change, which could confound interpretation of the relation between floods and flood-generating mechanisms, (4) concurrent water years of annual peak-streamflow and daily mean streamflow records are available, which enables assessment of antecedent flood conditions, and (5) the site is preferably currently (2022) active, which indicates current relevance of the site’s data that could continue to be relevant in the future. The 21 selected sites are representative of classes of spatial climatic variations for Hawai‘i and seasonal and other flow regimes for Southeast Alaska. For Hawai‘i, selected sites consist of at least one site each from the drier (leeward) and wetter (windward) side of each of the five largest islands (Kaua‘i, O‘ahu, Moloka‘i, Maui, and Hawai‘i). For Southeast Alaska, selected sites consist of at least one site each from five seasonal streamflow regimes variously controlled by rain, snowmelt, and high-elevation melt (Curran and Biles, 2021), and one site each from flow regimes controlled by large basins and glacial lake outburst floods.

This data release consists of a comma-delimited ascii file with attributes for 21 U.S. Geological Survey streamgage sites in Hawai‘i and Southeast Alaska selected to enable assessment of how floods might change in a future climate. Floods in Hawai‘i and Southeast Alaska have led to loss of human life; damage to agricultural crops, cultural and biological resources, infrastructure, and property; threats to public health; and conditions that are highly disruptive to residents and visitors. Floods are generated by atmospheric and terrestrial processes that may be enhanced or depressed in response to climate change. Understanding the mechanisms that generate floods can be useful for assessing how floods may change in future climates and developing adaptive-management strategies to cope with future floods. Key to improved understanding of floods in Hawai‘i and Southeast Alaska is identifying sites that are affected by known flood-generating mechanisms and that can be used to potentially assess the effects of these mechanisms on the magnitude and frequency of floods, both historically and in a future climate. Stakeholders representing scientific, public-safety, cultural, and ecologic perspectives from government, academic, and private institutions provided input for developing and refining site-selection criteria and selecting sites. The site-selection criteria were: (1) the site contributes to representing the primary flood-generating mechanisms in the study area, (2) the site's available annual peak-streamflow record contains a minimum of 10 years of record during the 1980-2020 period, with a preference for longer records, (3) streamflow at the site during 1980-2020 was not substantively affected by regulation, urban areas, and basin land-use change, which could confound interpretation of the relation between floods and flood-generating mechanisms, (4) concurrent water years of annual peak-streamflow and daily mean streamflow records are available, which enables assessment of antecedent flood conditions, and (5) the site is preferably currently (2022) active, which indicates current relevance of the site’s data that could continue to be relevant in the future. The 21 selected sites are representative of classes of spatial climatic variations for Hawai‘i and seasonal and other flow regimes for Southeast Alaska. For Hawai‘i, selected sites consist of at least one site each from the drier (leeward) and wetter (windward) side of each of the five largest islands (Kaua‘i, O‘ahu, Moloka‘i, Maui, and Hawai‘i). For Southeast Alaska, selected sites consist of at least one site each from five seasonal streamflow regimes variously controlled by rain, snowmelt, and high-elevation melt (Curran and Biles, 2021), and one site each from flow regimes controlled by large basins and glacial lake outburst floods.

The Geospatial Fabric for National Hydrologic Modeling (Viger and Bock, 2014; Bock and others, 2020) is a dataset of hydrographic features and spatial data designed for use within the National Hydrologic Model that covers the conterminous United States (CONUS), Hawaii, and most major river basins that flow in from Canada. This U.S. Geological Survey (USGS) data release consists of the geospatial fabric features and other related spatial datasets created to expand the National Hydrologic Model to Alaska. This child item consists of topographic data themes that cover the Geospatial Fabric for National Hydrologic Modeling, Alaska Domain. The 30-meter (m) raster datasets included under Topographic Derivatives are: digital elevation (dem.tif), topographic wetness index (TWI, twiX100.tif), slope (rise over run, slope.tif), aspect (asp.tif), flow accumulation (fac.tif), and flow direction (fdr.tif). All file formats are in GeoTIFF (Geographic Tagged Imaged Format), and are sourced from NHDPlus Version 2.0 raster layers (Environmental Protection Agency, 2019)

This dataset contains upstream watershed drainage areas for catchments comprising Catchment Fabric HUC12 units. The dataset is incomplete for Alaska.

This data release documents the data used for the associated publication "Evaluating hydrologic region assignment techniques for ungaged watersheds in Alaska, USA" (Barnhart and others, 2022) The data sets within this release are stored in 14 files: (1) Streamflow observations and sites used. (2) Statistically estimated streamflow values computed for each site. (3) Streamflow statistics computed from observed and estimated streamflow values at each site, basin characteristics for each site, and hydrologic regions (clusters) for each site. (4) A dataset describing the optimal number of hydrologic regions into which the considered sites were grouped. (5) P-values from a multiple comparisons analysis testing for statistical differences between clusters for each basin characteristic and streamflow statistic. (6) A matrix of zeros and ones describing the performance of each hydrologic region assignment technique considered in the publication associated with this release. (7) A dataset of variable importance generated by random forest modeling-based hydrologic region assignment techniques evaluated. (8-14) Daily datasets of simulated SnowModel (Liston and Elder, 2006) runoff (snowmelt + rainfall), precipitation, glacial melt, snow water equivalent, snow covered area, liquid precipitation, and air temperature for Alaska, USA at a 1 km grid cell size.