{"accessLevel": "public", "bureauCode": ["010:12"], "contactPoint": {"@type": "vcard:Contact", "fn": "Integrated Modeling &Prediction Division", "hasEmail": "mailto:gs-w-model-data-management@usgs.gov"}, "description": "This data set represents predicted nitrate concentration in\nground water used for drinking, in milligrams per liter, in the\nconterminous United States, and was generated by a national\nnonlinear regression model based on 14 input parameters.\nNolan and Hitt (2006) developed two national models to predict\ncontamination of ground water by nonpoint sources of\nnitrate. The nonlinear approach to national-scale Ground-WAter\nVulnerability Assessment (GWAVA) uses components representing\nnitrogen (N) sources, transport, and attenuation.\nOne model (GWAVA-S) predicts nitrate contamination of shallow\n(typically less than 5 meters deep), recently recharged ground\nwater, which may or may not be used for drinking.  The other\n(GWAVA-DW) predicts ambient nitrate concentration in deeper\nsupplies used for drinking.\nThis data set is a national map of nitrate concentration (in\nmilligrams per liter) in U.S ground water used for drinking as\npredicted by the GWAVA-DW model. The data set is one of 14\nspatial data sets (1 output data set and 13 input data sets)\nassociated with the GWAVA-DW model. Full details of the model\ndevelopment are in Nolan and Hitt (2006).\nThis data set represents the model output, which is depicted in\nfigure 3 of Nolan and Hitt (2006) that shows predicted nitrate\nconcentration in milligrams per liter in ground water used for\ndrinking. The model results can be used to indicate areas of the\nNation that may be vulnerable to nitrate contamination.\nFor inputs to the model, spatial attributes representing 13\nnitrogen loading and transport and attenuation factors were\ncompiled as raster data sets (1-km by 1-km grid cell size) for\nthe conterminous United States (see table 1).\n>Table 1.-- Parameters of nonlinear regression model for\n>           nitrate in ground water used for drinking (GWAVA-DW)\n>           and corresponding input spatial data sets.\n>           [kg, kilograms; km2, square kilometers.]\n>\n>Nitrogen Source Factors                  Data Set Name\n>   1 farm fertilizer (kg/hectare)        gwava-dw_ffer\n>   2 confined manure (kg/hectare)        gwava-dw_conf\n>   3 orchards/vineyards (percent)        gwava-dw_orvi\n>   4 population density  (people/km2)    gwava-dw_popd\n>\n>Transport to Aquifer Factors\n>   5 water input (km2/cm)                gwava-dw_wtin\n>   6 glacial till (yes/no)               gwava-dw_gtil\n>   7 semiconsolidated sand aquifers      gwava-dw_semc\n>     (yes/no)\n>   8 sandstone and carbonate rocks       gwava-dw_sscb\n>     (yes/no)\n>   9 drainage ditch (km2)                gwava-dw_ddit\n>  10 Hortonian overland flow             gwava-dw_hor\n>     (percent of streamflow)\n>\n>Attenuation Factors\n>  11 fresh surface water withdrawal      gwava-dw_swus\n>     for irrigation (megaliters/day)\n>  12 irrigation tailwater recovery (km2) gwava-dw_twre\n>  13 Dunne overland flow                 gwava-dw_dun\n>     (percent of streamflow)\n>  14 well depth (meters)                 -\n\"Farm fertilizer\" is the average annual nitrogen input from\ncommercial fertilizer applied to agricultural lands, 1992-2001, in\nkilograms per hectare.\n\"Confined manure\" is the average annual nitrogen input from\nconfined animal manure, 1992 and 1997, in kilograms per\nhectare.\n\"Orchards/vineyards\" is the percent of orchards/vineyards land\ncover classification.\n\"Population density\" is 1990 block group population density, in\npeople per square kilometer.\n\"Water input\" is the ratio of the total area of irrigated land\nto precipitation, in square kilometers per centimeter.\n\"Glacial till\" is the presence or absence of poorly sorted\nglacial till east of the Rocky Mountains.\n\"Semiconsolidated sand aquifers\" is the presence or absence of\nsemiconsolidated sand aquifers.\n\"Sandstone and carbonate rocks\" is the presence or absence of\nsandstone and carbonate rock aquifers.\n\"Drainage ditch\" is the area of National Resources Inventory surface\ndrainage, field ditch conservation practice, in square kilometers.\n\"Hortonian overland flow\" is infiltration excess overland flow\nestimated by TOPMODEL, in percent of streamflow.\n\"Fresh surface water withdrawal for irrigation\" is the amount of\nfresh surface water withdrawal for irrigation, in megaliters per day.\n\"Irrigation tailwater recovery\" is the area of National\nResources Inventory irrigation system, tailwater recovery\nconservation practice, in square kilometers.\n\"Dunne overland flow\" is saturation overland flow estimated by\nTOPMODEL, in percent of streamflow.\n\"Well depth\" is the depth of the well, in meters.  Well depth\nwas not compiled as a spatial data set.  Well depth equals 50\nmeters for the model simulation being presented.\nReference cited:\nNolan, B.T. and Hitt, K.J., 2006, Vulnerability of shallow\nground water and drinking-water wells to nitrate in the United\nStates: Environmental Science and Technology, vol. 40, no. 24,\npages 7834-7840.", "distribution": [{"@type": "dcat:Distribution", "accessURL": "https://doi.org/10.5066/P9IKUAX3", "description": "Landing page for access to the data", "format": "XML", "mediaType": "application/http", "title": "Digital Data"}, {"@type": "dcat:Distribution", "description": "The metadata original format", "downloadURL": "https://data.usgs.gov/datacatalog/metadata/USGS.efcd2e83-59aa-45bb-9f26-e1b6d464ef82.xml", "format": "XML", "mediaType": "text/xml", "title": "Original Metadata"}], "identifier": "http://datainventory.doi.gov/id/dataset/USGS_efcd2e83-59aa-45bb-9f26-e1b6d464ef82", "keyword": ["Drinking water", "Ground water", "Ground water contamination", "Ground water pollution", "Ground water susceptibility", "NAWQA", "National Water-Quality Assessment Program", "Nitrate", "Nitrate concentration", "Nonlinear model", "Nutrients", "USGS:efcd2e83-59aa-45bb-9f26-e1b6d464ef82", "environment", "geoscientificInformation", "inlandWaters"], "modified": "2020-11-17T00:00:00Z", "publisher": {"@type": "org:Organization", "name": "U.S. Geological Survey"}, "spatial": "-128.30785909, 22.73659812, -65.14338696, 51.857984", "theme": ["geospatial"], "title": "Vulnerability of shallow ground water and drinking-water wells to nitrate in the United States: Model of predicted nitrate concentration in U.S. ground water used for drinking (simulation depth 50 meters) -- Model output data set (gwava-dw_out)"}