Data Paper. Data Paper

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 km2). 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). Key words: aquatic ecology; dams; hydrologic condition; hydrologic modification; natural flow regime;reference stream gages; streamflow; stream gage network; stream gages; water withdrawal.文件清单：gages_basinchar_sept3_09.zip 该压缩包包含25个制表符分隔的ASCII文本文件（代表流域与站点特征）、1份包含变量说明的制表符分隔ASCII文本文件，以及1份Microsoft Excel电子表格，用于展示水文扰动指数得分的计算过程。 25个文本数据文件各包含6785条记录（每条对应一个溪流测站），以唯一标识符字段`GAGE_ID`进行标识。每个文件对应一类数据的一个或多个变量的取值，具体如下： 1. basinid.txt：溪流测站的基本标识特征（如名称、流域面积、经纬度、水资源分区）。 2. bas_classif.txt：参考/非参考站点分类及用于分类决策的主要定量信息，包括相关的ADR备注。 3. bas_morph.txt：流域地貌特征（如紧凑度系数）。 4. census_block.txt：基于人口普查街区级数据得到的人口密度。 5. census_county.txt：基于人口普查县级数据得到的人口密度。 6. climate.txt：气候特征（如平均降水量、平均气温）。 7. geology.txt：地质特征（如流域内主要地质类型）。 8. hydro.txt：基于GIS数据得到的水文特征（如测站处的河流等级、基流指数、径流占比）。 9. hydromod_dams.txt：流域内历史与现存大坝的相关信息。 10. hydromod_other.txt：其他人为水文改造相关信息（如流域内或干流上的运河占比、许可排污点的存在情况、取水估算量）。 11. infrastructure.txt：流域内道路密度与不透水面占比。 12. landscape_pat.txt：景观格局指数（如未开发土地的破碎度）。 13. lc01_basin.txt：2001年前后流域内各土地覆盖类型的占比。 14. lc_change92_01.txt：1992年至2001年间主要土地覆盖类型占比的变化估算值。 15. lc01_mains100.txt：干流100米缓冲带（干流两侧各100米范围）内2001年的土地覆盖类型占比。 16. lc01_mains800.txt：干流800米缓冲带（干流两侧各800米范围）内2001年的土地覆盖类型占比。 17. lc01_rip100.txt：流域内所有溪流两侧100米河岸缓冲带内2001年的土地覆盖类型占比。 18. lc01_rip800.txt：流域内所有溪流两侧800米河岸缓冲带内2001年的土地覆盖类型占比。 19. nutrient_app.txt：流域内氮磷养分投入的估算值。 20. pest_app.txt：流域内农业农药投入的估算值。 21. prot_areas.txt：流域内“受保护”土地覆盖区域的面积占比（如国家公园、荒野地区）。 22. reach.txt：用于关联NHDPlus获取河段数据的河段编码，以及该河段的河流类型（如StreamRiver、Canal等）。 23. regions.txt：站点位置及流域在各区域的面积占比（如美国环境保护署二级或三级生态区）。 24. soils.txt：土壤特征。 25. topo.txt：地形特征（如流域平均海拔、平均坡度）。 文件`gages_variable_desc_sept3_09.txt`包含上述数据文件中各变量的元数据，该文件共包含375条记录，每条记录对应一个特定变量的详细说明，格式为制表符分隔的文本文件。 Microsoft Excel电子表格文件名为`disturb_index6785_sept3_09.xls`，仅作为演示扰动指数得分赋值方式的便利工具提供，若需修改该表格，相关说明可在“notes”工作表中查看。 数据集说明 径流是河流与溪流生态系统的核心控制因子。掌握自然径流情势（natural flow regime）有助于评估特定溪流的水文属性是否受到人类活动改造，并为溪流径流修复设定具体目标。由于多数溪流未设置测站或已受人类活动改造，通常仅能通过邻近的高质量参考测站（即受人类干扰最少的测流站点）估算径流特征，以表征自然径流情势。 若能获取一套全国统一、实时更新的相对未受干扰流域的测站数据库，将有助于提升对未受人类活动改造的自然径流的评估能力。 作为表征径流对生态状况影响的全国性研究的一部分，本数据集整合了6785个美国地质调查局（United States Geological Survey, USGS）溪流测站及其上游流域的相关数据。这些站点涵盖美国本土范围内所有满足以下条件的USGS溪流测站：1950年至2007年间拥有至少20年完整年度径流记录，且可可靠绘制流域边界（流域面积中位数为578 km²）。 研究团队从全国数据源中计算并整合了数百项流域与站点特征，包括环境属性（如气候、地质、土壤、地形）及人为影响因素（如土地利用、道路、大坝或运河的存在情况）。此外，研究团队针对九个大区域内的流域进行了参考质量评估，以用于表征受人类活动影响最小的自然径流条件的研究。 参考质量评估采用三项主要标准：（1）基于GIS衍生变量的流域内人为改造定量指数；（2）通过最新高分辨率影像与地形图对每个溪流测站及流域进行目视检查；（3）从USGS年度水文数据报告中获取的人为影响相关信息。 从6785个站点中，研究团队筛选出1512个具有参考质量的溪流测站。 本数据集包含为这些流域获取的所有数据以及参考条件评估结果，命名为GAGES（Geospatial Attributes of Gages for Evaluating Streamflow，溪流测站径流评估地理空间属性）。 关键词 水生生态学；大坝；水文状况；水文改造；自然径流情势；参考溪流测站；径流；溪流测站网络；溪流测站；取水