This network analysis calculates the values of 57 variables for incremental gaged areas (IGAs), which are the drainage areas of each gage downstream of other gages and, if source data are spatially continuous, for 12-digit hydrologic unit code watersheds (HUC12s). The variable "type" determines the values used creating for cumulative distributions and the criteria for identifying priority monitoring areas.
| Topic and Variable | Units | Source | Spatial Extent and Resolution of Source Data | Variable Type |
|---|---|---|---|---|
| Physical Geography | ||||
| MeanElev: Mean elevation of land surface | meters above sea level | Wieczorek and others (2018) | CONUS; NHD catchments | gradient |
| DrainageArea: Drainage area based on routing of NHD catchments (CONUS) or HUC12s (non-CONUS) | square kilometers | Wieczorek and others (2018); USGS (2021) | US; either NHD catchments or HUC12s (drainage area extends to downstream end of catchment or HUC12 that encompasses the gage and will be larger than drainage area delineated upstream from the gage) | gradient |
| SurfGeol: Fraction of area in dominant surficial geologic class from Soller and others (2009) | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | multicategory |
| BasinSlope: Mean basin slope | meter per meter | Wieczorek and others (2018) | CONUS; NHD catchments | gradient |
| StreamSlope: Mean stream slope | meter per meter | Wieczorek and others (2018) | CONUS; NHD catchments | gradient |
| Water Balance and Extreme Flows | ||||
| PPT: Normal annual precipitation volume for 1971-2000 | cubic kilometers per year | Wieczorek and others (2018) | CONUS; NHD catchments | value-value |
| ET: Actual mean annual evapotranspiration volume for 2000-2009 estimated from Simplified Surface Energy Balance | cubic kilometers per year | Maupin and others (2012); Wieczorek and others (2018) | CONUS; NHD catchments | value-value |
| Withdrawals: Surface water and groundwater withdrawal volume for 2010 estimated as product of county-mean value and IGA or HUC12 area | cubic kilometers per year | Maupin and others (2014); Wieczorek and others (2018) | CONUS; NHD catchments | value-value |
| IncrQmean: Difference in median annual mean streamflow between upstream and downstream gages for IGA | cubic meters per second | USGS (2021) | USGS streamflow gages with 5 years of daily streamflow values for water years 1981 to 2020 | value-dvalue |
| IncrQmin: Difference in median annual minimum daily streamflow between upstream and downstream gages for IGA | cubic meters per second | USGS (2021) | USGS streamflow gages with 5 years of daily streamflow values for water years 1981 to 2020 | value-dvalue |
| IncrQmax: Difference in median annual maximum daily streamflow between upstream and downstream gages for IGA | cubic meters per second | USGS (2021) | USGS streamflow gages with 5 years of daily streamflow values for water years 1981 to 2020 | value-dvalue |
| Hydroperiod: Median annual fraction of year that daily mean streamflow > 0 at the downstream gage | fraction of year | USGS (2021) | USGS streamflow gages with 5 years of daily streamflow values for water years 1981 to 2020 | gradient |
| Water Quality | ||||
| ImpairedWQ: Stream segments listed as impaired for water quality under the Clean Water Act, Section 303d | kilometers | USEPA (2014) | US; spatially continuous | logical-length |
| MajorNPDES: Major discharges permitted under the National Pollutant Discharge Elimination System | count | Wieczorek and others (2018) | CONUS; NHD catchments | value-value |
| IncrTDS: Mean annual incremental (difference between upstream and downstream) load of total dissolved solids detrended for 2000 base year | metric tons per year | Anning and Flynn (2014) | USGS streamflow gages in CONUS with published long-term mean annual total dissolved solids load | value-dvalue |
| IncrTN: Mean annual incremental (difference between upstream and downstream) load of total nitrogen detrended for 2012 base year | metric tons per year | Saad and others (2019) | USGS streamflow gages in CONUS with long-term mean annual total nitrogen load | value-dvalue |
| IncrTP: Mean annual incremental (difference between upstream and downstream) load of total phosphorous detrended for 2012 base year | metric tons per year | Saad and others (2019) | USGS streamflow gages in CONUS with long-term mean annual total phosphorous load | value-dvalue |
| IncrTSS: Mean annual incremental (difference between upstream and downstream) load of total suspended sediment detrended for 2012 base year | metric tons per year | Saad and others (2019) | USGS streamflow gages in CONUS with published long-term mean annual total suspended sediment load | value-dvalue |
| Climate | ||||
| ClimDiv: Fraction of IGA in dominant NOAA climate division (nCLIMDIV) | fraction of area | NOAA (2020) | US; spatially continuous | multicategory |
| MinTempLT0: Fraction of IGA or HUC12 where normal annual minimum monthly temperature is less than zero | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| CoastalStreams: Stream segments in catchments with a minimum elevation less than 10 m ABSL | kilometers | Wieczorek and others (2018) | CONUS; NHD catchments | logical-length |
| Ecological Integrity | ||||
| Ecoregion: Fraction of IGA or HUC12 in dominant Ecoregion Level III | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | multicategory |
| WildScenicRivers: Fraction of stream length in IGA or HUC designated as Wild and Scenic River | kilometers | National Wild and Scenic Rivers Systems (2019) | US; spatially continuous | logical-length |
| Undeveloped: Fraction of IGA or HUC12 with codes 11, 12, 41, 42, 43, 52, 71, 90, or 95 (water, barren, snow/ice, shrub, grass, forest, or wetland) | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| Wilderness: Fraction of IGA or HUC12 designated as Wilderness | fraction of area | USGS (2000) | US; spatially continuous | mean-area |
| ReservoirRegulation: Normal reservoir storage for drainage area divided by annual precipitation volume for drainage area | years | USACE (2013); Konrad and others (2022) | CONUS; large dams | gradient |
| Land Cover | ||||
| Barren: National Land Cover Dataset (NLCD) 2016 code 31 | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| Water: NLCD 2016 code 11 | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| SnowIce: NLCD 2016 code 12 | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| Wetland: NLCD 2016 code 90 or 95 | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| Forest: NLCD 2016 code 41, 42, or 43 | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| Shrub: NLCD 2016 code 52 | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| Grass: NLCD 2016 code 71 | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| Pasture: NLCD 2016 code 81 | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| Cultivated: NLCD 2016 code 82 | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| DevOpen: NLCD 2016 code 21 | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| DevLowMed: NLCD 2016 code 22 or 23 | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| DevHigh: NLCD 2016 code 24 | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| RiparianBarren: NLCD 2011 code 31 in 50 m buffer around streams | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| RiparianWater: NLCD 2011 code 11 in 50 m buffer around streams | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| RiparianSnowIce: NLCD 2011 code 12 in 50 m buffer around streams | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| RiparianWetland: NLCD 2011 code 90 or 95 in 50 m buffer around streams | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| RiparianForest: NLCD 2011 code 41, 42, or 43 in 50 m buffer around streams | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| RiparianShrub: NLCD 2011 code 52 in 50 m buffer around streams | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| RiparianGrass: NLCD 2011 code 71 in 50 m buffer around streams | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| RiparianPasture: NLCD 2011 code 81 in 50 m buffer around streams | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| RiparianCultivated: NLCD 2011 code 82 in 50 m buffer around streams | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| RiparianDevOpen: NLCD 2011 code 21 in 50 m buffer around streams | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| RiparianDevLowMed: NLCD 2011 code 22 or 23 in 50 m buffer around streams | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| RiparianDevHigh: NLCD 2011 code 24 in 50 m buffer around streams | fraction of area | Wieczorek and others (2018) | CONUS; NHD catchments | mean-area |
| Land Management | ||||
| NativeAmerican: Fraction of IGA or HUC12 managed by Native American tribes | fraction of area | USGS (2014) | CONUS; spatially continuous | mean-area |
| BLM: Fraction of IGA or HUC12 managed by Bureau of Land Management | fraction of area | USGS (2014) | US; spatially continuous | mean-area |
| NPS: Fraction of IGA or HUC12 managed by National Park Service | fraction of area | USGS (2014) | US; spatially continuous | mean-area |
| FWS: Fraction of IGA or HUC12 managed by US Fish and Wildlife Service | fraction of area | USGS (2014) | US; spatially continuous | mean-area |
| FS: Fraction of IGA or HUC12 managed by US Forest Service | fraction of area | USGS (2014) | US; spatially continuous | mean-area |
| DOD: Fraction of IGA or HUC12 managed by Deparment of Defense | fraction of area | USGS (2014) | US; spatially continuous | mean-area |
| Population | ||||
| Population: Number of people | count | Wieczorek and others (2018) | CONUS; NHD catchments | value-value |
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