DOI: 10.6084/m9.figshare.3544358
title: Data Paper. Data Paper

description: File List gages_basinchar_sept3_09.zip -- Zipped file containing 25 tab-delimited ASCII text files, representing watershed and site characteristics, one ASCII tab-delimited text file containing variable descriptions, and one MS Excel spreadsheet showing the hydrologic disturbance index score calculation. Each of the 25 text data files has 6785 records (one record for each stream gage), identified by the unique identifier field GAGE_ID. Each file contains data values for one or more variables for a class of data, as described below: The 25 files are: basinid.txt: Basic identification characteristics of the stream gage (e.g., name, drainage area, lat/long, water resources region). bas_classif.txt: Reference/non-reference classification and primary quantitative information that went into the classification decision, including pertinent ADR remarks. bas_morph.txt: Basin morphology (e.g., compactness ratio). census_block.txt: Population densities derived from Census Block-level data. census_county.txt: Population densities derived from Census County-level data. climate.txt: Climate characteristics (e.g., mean precipitation, temperature). geology.txt: Geological characteristics (e.g., dominant geology in watershed). hydro.txt: Hydrologic characteristics derived from GIS data (e.g., stream order at the streamgage, base-flow-index, percent runoff). hydromod_dams.txt: Information about historical and current dams in the watershed. hydromod_other.txt: Information about other anthropogenic hydrologic modifications (e.g., percent canals in watershed or on mainstem, presence of permitted pollution discharge sites, estimate of water withdrawal). infrastructure.txt: Road density and percent impervious surfaces in watershed. landscape_pat.txt: Landscape pattern metric(s) (e.g., fragmentation of undeveloped land). lc01_basin.txt: Percentages of land cover circa year 2001 in the watershed. lc_change92_01.txt: Estimates of changes from 1992 to 2001 in percentages of major land cover classes. lc01_mains100.txt: Percentages of land cover classes in 100-m mainstem buffer (100 m each side of mainstem stream line). lc01_mains800.txt: Percentages of land cover classes in 800-m mainstem buffer (800 m each side of mainstem streamline). lc01_rip100.txt: Percentages of land cover classes in 100-m riparian buffer (100 m each side of all streamlines in watershed). lc01_rip800.txt: Percentages of land cover classes in 800-m riparian buffer (800 m each side of all streamlines in watershed). nutrient_app.txt: Estimates of nitrogen and phosphorus application in the watershed. pest_app.txt: Estimates of agricultural pesticide application in the watershed. prot_areas.txt: Percent area of the watershed in "protected" land cover zones (e.g., National Parks, Wilderness Areas) reach.txt: Reachcode for linking to NHDPlus for obtaining reach data, as well as the type of stream at the reach (StreamRiver, Canal, etc.). regions.txt: Site location and percent of watershed area in various regions (e.g., EPA Level II or III ecoregions). soils.txt: Soils characteristics. topo.txt: Topographic characteristics (e.g., mean basin elevation, mean slope). The file gages_variable_desc_sept3_09.txt contains metadata for the variables in the data files above. This metadata file has 375 records; each record has detailed information about a specific variable. The file is in tab-delimited text format. The MS Excel spreadsheet is named disturb_index6785_sept3_09.xls. This file is provided as a convenience only as demonstration of how the disturbance index scores were assigned. Instructions on how to modify the spreadsheet, if so desired, are provided in the "notes" worksheet. Description Streamflow is a controlling element in the ecology of rivers and streams. Knowledge of the natural flow regime facilitates the assessment of whether specific hydrologic attributes have been altered by humans in a particular stream and the establishment of specific goals for streamflow restoration. Because most streams are ungaged or have been altered by human influences, characterizing the natural flow regime is often only possible by estimating flow characteristics based on nearby stream gages of reference quality, i.e., gaged locations that are least-disturbed by human influences. The ability to evaluate natural streamflow, that which is not altered by human activities, would be enhanced by the existence of a nationally consistent and up-to-date database of gages in relatively undisturbed watersheds. As part of a national effort to characterize streamflow effects on ecological condition, data for 6785 U.S. Geological Survey (USGS) stream gages and their upstream watersheds were compiled. The sites comprise all USGS stream gages in the conterminous United States with at least 20 years of complete-year flow record from 1950–2007, and for which watershed boundaries could reliably be delineated (median size = 578 km<sup>2</sup>). Several hundred watershed and site characteristics were calculated or compiled from national data sources, including environmental features (e.g., climate, geology, soils, topography) and anthropogenic influences (e.g., land use, roads, presence of dams, or canals). In addition, watersheds were assessed for their reference quality within nine broad regions for use in studies intended to characterize streamflows under conditions minimally influenced by human activities. Three primary criteria were used to assess reference quality: (1) a quantitative index of anthropogenic modification within the watershed based on GIS-derived variables, (2) visual inspection of every stream gage and drainage basin from recent high-resolution imagery and topographic maps, and (3) information about man-made influences from USGS Annual Water Data Reports. From the set of 6785 sites, we identified 1512 as reference-quality stream gages. All data derived for these watersheds as well as the reference condition evaluation are provided as an online data set termed GAGES (geospatial attributes of gages for evaluating streamflow). <i>Key words: aquatic ecology; dams; hydrologic condition; hydrologic modification; natural flow regime;reference stream gages; streamflow; stream gage network; stream gages; water withdrawal.</i>