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TwitterFrom the site: “A Digital Raster Graphic (DRG) is a scanned image of a U.S. Geological Survey (USGS) topographic map. An unclipped scanned image includes all marginal information, while a clipped or seamless scanned image clips off the collar information. DRGs may be used as a source or background layer in a geographic information system, as a means to perform quality assurance on other digital products, and as a source for the collection and revision of digital line graph data. The DRGs also can be merged with other digital data (e.g., digital elevation model or digital orthophotoquad data), to produce a hybrid digital file.
The output resolution of a DRG varies from 250 to 500 dots per inch. The horizontal positional accuracy of the DRG matches the accuracy of the published source map. To be consistent with other USGS digital data, the image is cast on the UTM projection, and therefore, will not always be consistent with the credit note on the image collar. Only the area inside the map neatline is georeferenced, so minor distortion of the text may occur in the map collar. Refer to the scanned map collar or online Map List for the currentness of the DRG.”
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TwitterA Digital Raster Graphic (DRG) is a scanned image of a U.S. Geological Survey (USGS) topographic map. An unclipped scanned image includes all marginal information, while a clipped or seamless scanned image clips off the collar information. DRGs may be used as a source or background layer in a geographic information system, as a means to perform quality assurance on other digital products, and as a source for the collection and revision of digital line graph data. The DRGs also can be merged with other digital data (e.g., digital elevation model or digital orthophotoquad data), to produce a hybrid digital file. The output resolution of a DRG varies from 250 to 500 dots per inch. The horizontal positional accuracy of the DRG matches the accuracy of the published source map. To be consistent with other USGS digital data, the image is cast on the UTM projection, and therefore, will not always be consistent with the credit note on the image collar. Only the area inside the map neatline is georeferenced, so minor distortion of the text may occur in the map collar. Refer to the scanned map collar or online Map List for the currentness of the DRG.
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TwitterLink to the ScienceBase Item Summary page for the item described by this metadata record. Service Protocol: Link to the ScienceBase Item Summary page for the item described by this metadata record. Application Profile: Web Browser. Link Function: information
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TwitterDigitized from USGS 1:24,000-scale Digital Raster Graphics (scanned topographic maps) by the West Virginia Department of Environmental Protection. WVGISTC dissolved county boundaries to create the state boundary. Published May 2002.Coordinate System: Lat/Long NAD 1983,UTM NAD 1983
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TwitterWest Virginia county map boundaries divided by county map sheets.The West Virginia County Boundaries layer was digitized off from USGS 1:24,000-scale Digital Raster Graphics (scanned topographic maps) by the West Virginia Department of Environmental Protection. First published in January 2002, updated with Census 2000 attribute data and re-published in March 2005. West Virginia Department of Transportation-Division of Highways, Geographic Transportation Information Section (GTI), processed into map sheet index, 2007-2010.
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TwitterDigitized off of USGS 1:24,000-scale Digital Raster Graphics (scanned topographic maps) by the West Virginia Department of Environmental Protection. First published January 2002, updated with Census 2000 attribute data and re-published March 2005.
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TwitterLink to the ScienceBase Item Summary page for the item described by this metadata record. Service Protocol: Link to the ScienceBase Item Summary page for the item described by this metadata record. Application Profile: Web Browser. Link Function: information
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TwitterThe mapped area boundary, flood inundation extents, and depth rasters were created to provide an estimated extent of flood inundation along the Cherry River within the communities of Richwood and Fenwick, West Virginia. These geospatial data include the following items: 1. cherry_bnd; shapefile containing the polygon showing the mapped area boundary for the Cherry River flood maps, 2. cherry_hwm; shapefile containing high-water mark points, 3. polygon_cherry_hwm; shapefile containing mapped extent of flood inundation, derived from the water-surface elevation surveyed at high-water marks, 4. depth_hwm; raster file for the flood depths derived from the water-surface elevation surveyed at high-water marks, 5. polygon_cherry_dem; shapefile containing mapped extent of flood inundation, derived from the height above ground recorded at high-water marks and the digital elevation model (DEM) raster, 6. depth_dem; raster file for the flood depths derived from the height above ground recorded at high-water marks and the digital elevation model raster. The upstream and downstream mapped area extent is limited to the upstream-most and downstream-most high-water mark locations. In areas of uncertainty of flood extent, the mapped area boundary is lined up with the flood inundation polygon extent. The mapped area boundary polygon was used to extract the final flood inundation polygon and depth raster from the water-surface elevation raster file. Depth raster files were created using the "Topo to Raster" tool in ArcMap (ESRI, 2012). For this study two sets of inundation layers were generated for each reach. One raster file showing flood depths, "depth_hwm", was created by using high-water mark water-surface elevation values on the land surface and a digital elevation model. However, differences in elevation between the surveyed water-surface elevation values at HWM’s and the land-surface elevation from the digital elevation model data provided uncertainty in the inundation extent of the generated layers. Often times elevation differences of +/- 20 feet were noticed between the surveyed elevation from a HWM on the land surface and the digital elevation model land-surface elevation. Due to these elevation differences, we incorporated a second method of interpolating the water-surface layer. The recorded height above ground value from the surveyed HWM was added to the digital elevation model land-surface elevation at that point. This created a new water-surface elevation value to be used with the “Topo to Raster” interpolation method to create a second depth raster, "depth_dem". Both sets of inundation layers are provided.
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TwitterDigitized from USGS 1:24,000-scale Digital Raster Graphics (scanned topographic maps) by the West Virginia Department of Environmental Protection. First published January 2002, updated with Census 2000 attribute data and re-published March 2005. Scale: 1:24000. Attribute Information includes Federal Information Processing Standards (FIPS) codes and 2000 Census data.Coordinate System: NAD_1983_UTM_Zone_17N
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TwitterVersion 10.0 (Alaska, Hawaii and Puerto Rico added) of these data are part of a larger U.S. Geological Survey (USGS) project to develop an updated geospatial database of mines, mineral deposits, and mineral regions in the United States. Mine and prospect-related symbols, such as those used to represent prospect pits, mines, adits, dumps, tailings, etc., hereafter referred to as “mine” symbols or features, have been digitized from the 7.5-minute (1:24,000, 1:25,000-scale; and 1:10,000, 1:20,000 and 1:30,000-scale in Puerto Rico only) and the 15-minute (1:48,000 and 1:62,500-scale; 1:63,360-scale in Alaska only) archive of the USGS Historical Topographic Map Collection (HTMC), or acquired from available databases (California and Nevada, 1:24,000-scale only). Compilation of these features is the first phase in capturing accurate locations and general information about features related to mineral resource exploration and extraction across the U.S. The compilation of 725,690 point and polygon mine symbols from approximately 106,350 maps across 50 states, the Commonwealth of Puerto Rico (PR) and the District of Columbia (DC) has been completed: Alabama (AL), Alaska (AK), Arizona (AZ), Arkansas (AR), California (CA), Colorado (CO), Connecticut (CT), Delaware (DE), Florida (FL), Georgia (GA), Hawaii (HI), Idaho (ID), Illinois (IL), Indiana (IN), Iowa (IA), Kansas (KS), Kentucky (KY), Louisiana (LA), Maine (ME), Maryland (MD), Massachusetts (MA), Michigan (MI), Minnesota (MN), Mississippi (MS), Missouri (MO), Montana (MT), Nebraska (NE), Nevada (NV), New Hampshire (NH), New Jersey (NJ), New Mexico (NM), New York (NY), North Carolina (NC), North Dakota (ND), Ohio (OH), Oklahoma (OK), Oregon (OR), Pennsylvania (PA), Rhode Island (RI), South Carolina (SC), South Dakota (SD), Tennessee (TN), Texas (TX), Utah (UT), Vermont (VT), Virginia (VA), Washington (WA), West Virginia (WV), Wisconsin (WI), and Wyoming (WY). The process renders not only a more complete picture of exploration and mining in the U.S., but an approximate timeline of when these activities occurred. These data may be used for land use planning, assessing abandoned mine lands and mine-related environmental impacts, assessing the value of mineral resources from Federal, State and private lands, and mapping mineralized areas and systems for input into the land management process. These data are presented as three groups of layers based on the scale of the source maps. No reconciliation between the data groups was done.Datasets were developed by the U.S. Geological Survey Geology, Geophysics, and Geochemistry Science Center (GGGSC). Compilation work was completed by USGS National Association of Geoscience Teachers (NAGT) interns: Emma L. Boardman-Larson, Grayce M. Gibbs, William R. Gnesda, Montana E. Hauke, Jacob D. Melendez, Amanda L. Ringer, and Alex J. Schwarz; USGS student contractors: Margaret B. Hammond, Germán Schmeda, Patrick C. Scott, Tyler Reyes, Morgan Mullins, Thomas Carroll, Margaret Brantley, and Logan Barrett; and by USGS personnel Virgil S. Alfred, Damon Bickerstaff, E.G. Boyce, Madelyn E. Eysel, Stuart A. Giles, Autumn L. Helfrich, Alan A. Hurlbert, Cheryl L. Novakovich, Sophia J. Pinter, and Andrew F. Smith.USMIN project website: https://www.usgs.gov/USMIN
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TwitterAn orthoimage is remotely sensed image data in which displacement of features in the image caused by terrain relief and sensor orientation has been mathematically removed. Orthoimagery combines the image characteristics of a photograph with the geometric qualities of a map. For this dataset, 2-foot pixel resolution natural color digital orthimages were obtained from the West Virginia Statewide Addressing and Mapping Board. The orthoimages were mosaicked and reprojected by the USGS from the original 2-foot pixel, West Virginia North and South State Plane (feet) Coordinate Systems to Universal Transverse Mercator (UTM) (meters), Zone 17, NAD83 datum. Each orthoimage (DOQQ) provides the equivalent to a quarter of a 7.5-minute map (3.75 minutes of latitude and longitude) with overedge. The overedge is approximately 300 meters beyond the extremes of the corners of coverage. The naming convention is based on the U.S. Geological Survey 1:24,000 Topographic Map Series with the quadrant abbreviation, i.e. athens_ne.tif, etc. This data set covers the entire state of West Virginia including into UTM zone 18 on the east edge.
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TwitterDrainage basin areas for 376 USGS streamgages in West Virginia and adjacent states were delineated digitally. The USGS Watershed Boundary Dataset HUC12 sub-watershed lines were used as outer limits of basins, and heads-up digitizing was used to delineate boundaries from the stream gage to the HUC12 boundary. The USGS National Map was used, as background, to show both contour lines and digital elevation to highlight drainage basin divides, ridges, and valleys. Basins were delineated for (1) all active continuous-flow and crest-stage streamgages, in West Virginia, through water year 2020, (2) selected inactive streamgages, in West Virginia and adjacent states, that were used in the flood-frequency report prepared by Wiley and Atkins (2010), (3) Selected streamflow stations in West Virginia included in the low-flow report by Wiley and Atkins (2006), 4) historic West Virginia streamgages with published daily flow values, and (5) selected stage-only streamgages.For some historical streamgages included in this dataset, either the basin perimeter or the stream location have been altered by human activity since the gage was operated. Drainage basins for these streamgages were digitized from topographic maps contemporaneous with the period of streamflow record, so that their published drainage areas would continue to accurately reflect the drainage area when streamflow data were collected. Streamgage 03198022 was digitized from the 1971 topographic map because the basin perimeter was altered by construction after the streamgage was discontinued, and streamgages 03212567 and 03213495 were digitized from 1968 topographic maps because the basin perimeter was altered by surface mining after the streamgage was discontinued. Streamgages 03055040 and 03059500 were operated on streams that have been moved substantially since the streamgages were discontinued; basins for these streamgages were digitized from the historic streamgage locations, which are no longer on streams. Six streamgages, 01607000, 01636451, 01636462, 03060000, 03181000, and 03183200 are included in the point file for completeness, although no basins were delineated for them because they were on springs or karst-affected streams where the surface drainage basin was known to have little relationship to the actual drainage basin. Drainage basin areas, provided in this data release were updated in the National Water Information System (NWIS). Provided in the file 'WVBasinboundary.zip' is a geodatabase with (1) a point feature class of streamgage stations as described above (WV_Surfacewater_sites), (2) a feature dataset that contains the digitized drainage areas in polygon(WVBoundary_poly) and line (WVboundary_arc) format.
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TwitterThe mapped area boundary, flood inundation extents, and depth rasters were created to provide an estimated extent of flood inundation along the Elk River within communities in Kanawha and Clay Counties, West Virginia. These geospatial data include the following items: 1. elk_bnd; shapefile containing the polygon showing the mapped area boundary for the Elk River flood maps, 2. elk_hwm; shapefile containing high-water mark points, 3. polygon_elk_hwm; shapefile containing mapped extent of flood inundation, derived from the water-surface elevation surveyed at high-water marks, 4. depth_hwm; raster file for the flood depths derived from the water-surface elevation surveyed at high-water marks, 5. polygon_elk_dem; shapefile containing mapped extent of flood inundation, derived from the height above ground recorded at high-water marks and the digital elevation model (DEM) raster, 6. depth_dem; raster file for the flood depths derived from the height above ground recorded at high-water marks and the digital elevation model raster. The upstream and downstream mapped area extent is limited to the upstream-most and downstream-most high-water mark locations. In areas of uncertainty of flood extent, the mapped area boundary is lined up with the flood inundation polygon extent. The mapped area boundary polygon was used to extract the final flood inundation polygon and depth raster from the water-surface elevation raster file. Depth raster files were created using the "Topo to Raster" tool in ArcMap (ESRI, 2012). For this study two sets of inundation layers were generated for each reach. One raster file showing flood depths, "depth_hwm", was created by using high-water mark water-surface elevation values on the land surface and a digital elevation model. However, differences in elevation between the surveyed water-surface elevation values at HWM’s and the land-surface elevation from the digital elevation model data provided uncertainty in the inundation extent of the generated layers. Often times elevation differences of +/- 20 feet were noticed between the surveyed elevation from a HWM on the land surface and the digital elevation model land-surface elevation. Due to these elevation differences, we incorporated a second method of interpolating the water-surface layer. The recorded height above ground value from the surveyed HWM was added to the digital elevation model land-surface elevation at that point. This created a new water-surface elevation value to be used with the “Topo to Raster” interpolation method to create a second depth raster, "depth_dem". Both sets of inundation layers are provided.
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TwitterThe mapped area boundary, flood inundation extents, and depth rasters were created to provide an estimated extent of flood inundation along the New River within the community of Hinton, West Virginia. These geospatial data include the following items: 1. newriver_bnd; shapefile containing the polygon showing the mapped area boundary for the New River flood maps, 2. newriver_hwm; shapefile containing high-water mark points, 3. polygon_newriver_hwm; shapefile containing mapped extent of flood inundation, derived from the water-surface elevation surveyed at high-water marks, 4. depth_hwm; raster file for the flood depths derived from the water-surface elevation surveyed at high-water marks, 5. polygon_newriver_dem; shapefile containing mapped extent of flood inundation, derived from the height above ground recorded at high-water marks and the digital elevation model (DEM) raster, 6. depth_dem; raster file for the flood depths derived from the height above ground recorded at high-water marks and the digital elevation model raster. The upstream and downstream mapped area extent is limited to the upstream-most and downstream-most high-water mark locations. In areas of uncertainty of flood extent, the mapped area boundary is lined up with the flood inundation polygon extent. The mapped area boundary polygon was used to extract the final flood inundation polygon and depth raster from the water-surface elevation raster file. Depth raster files were created using the "Topo to Raster" tool in ArcMap (ESRI, 2012). For this study two sets of inundation layers were generated for each reach. One raster file showing flood depths, "depth_hwm", was created by using high-water mark water-surface elevation values on the land surface and a digital elevation model. However, differences in elevation between the surveyed water-surface elevation values at HWM’s and the land-surface elevation from the digital elevation model data provided uncertainty in the inundation extent of the generated layers. Often times elevation differences of +/- 20 feet were noticed between the surveyed elevation from a HWM on the land surface and the digital elevation model land-surface elevation. Due to these elevation differences, we incorporated a second method of interpolating the water-surface layer. The recorded height above ground value from the surveyed HWM was added to the digital elevation model land-surface elevation at that point. This created a new water-surface elevation value to be used with the “Topo to Raster” interpolation method to create a second depth raster, "depth_dem". Both sets of inundation layers are provided.
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TwitterThe mapped area boundary, flood inundation extents, and depth rasters were created to provide an estimated extent of flood inundation along the Meadow River and Sewell Creek within the community of Rainelle, West Virginia. These geospatial data include the following items: 1. meadow_sewell_bnd; shapefile containing the polygon showing the mapped area boundary for the Meadow River and Sewell Creek flood maps, 2. meadow_sewell_hwm; shapefile containing high-water mark points, 3. polygon_meadow_sewell_hwm; shapefile containing mapped extent of flood inundation, derived from the water-surface elevation surveyed at high-water marks, 4. depth_hwm; raster file for the flood depths derived from the water-surface elevation surveyed at high-water marks, 5. polygon_meadow_sewell_dem; shapefile containing mapped extent of flood inundation, derived from the height above ground recorded at high-water marks and the digital elevation model (DEM) raster, 6. depth_dem; raster file for the flood depths derived from the height above ground recorded at high-water marks and the digital elevation model raster. The upstream and downstream mapped area extent is limited to the upstream-most and downstream-most high-water mark locations. In areas of uncertainty of flood extent, the mapped area boundary is lined up with the flood inundation polygon extent. The mapped area boundary polygon was used to extract the final flood inundation polygon and depth raster from the water-surface elevation raster file. Depth raster files were created using the "Topo to Raster" tool in ArcMap (ESRI, 2012). For this study two sets of inundation layers were generated for each reach. One raster file showing flood depths, "depth_hwm", was created by using high-water mark water-surface elevation values on the land surface and a digital elevation model. However, differences in elevation between the surveyed water-surface elevation values at HWM’s and the land-surface elevation from the digital elevation model data provided uncertainty in the inundation extent of the generated layers. Often times elevation differences of +/- 20 feet were noticed between the surveyed elevation from a HWM on the land surface and the digital elevation model land-surface elevation. Due to these elevation differences, we incorporated a second method of interpolating the water-surface layer. The recorded height above ground value from the surveyed HWM was added to the digital elevation model land-surface elevation at that point. This created a new water-surface elevation value to be used with the “Topo to Raster” interpolation method to create a second depth raster, "depth_dem". Both sets of inundation layers are provided.
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TwitterThe mapped area boundary, flood inundation extents, and depth rasters were created to provide an estimated extent of flood inundation along the Gauley River within the community of Camden-on-Gauley, West Virginia. These geospatial data include the following items: 1. gauley_bnd; shapefile containing the polygon showing the mapped area boundary for the Gauley River flood maps, 2. gauley_hwm; shapefile containing high-water mark points, 3. polygon_gauley_hwm; shapefile containing mapped extent of flood inundation, derived from the water-surface elevation surveyed at high-water marks, 4. depth_hwm; raster file for the flood depths derived from the water-surface elevation surveyed at high-water marks, 5. polygon_gauley_dem; shapefile containing mapped extent of flood inundation, derived from the height above ground recorded at high-water marks and the digital elevation model (DEM) raster, 6. depth_dem; raster file for the flood depths derived from the height above ground recorded at high-water marks and the digital elevation model raster. The upstream and downstream mapped area extent is limited to the upstream-most and downstream-most high-water mark locations. In areas of uncertainty of flood extent, the mapped area boundary is lined up with the flood inundation polygon extent. The mapped area boundary polygon was used to extract the final flood inundation polygon and depth raster from the water-surface elevation raster file. Depth raster files were created using the "Topo to Raster" tool in ArcMap (ESRI, 2012). For this study two sets of inundation layers were generated for each reach. One raster file showing flood depths, "depth_hwm", was created by using high-water mark water-surface elevation values on the land surface and a digital elevation model. However, differences in elevation between the surveyed water-surface elevation values at HWM’s and the land-surface elevation from the digital elevation model data provided uncertainty in the inundation extent of the generated layers. Often times elevation differences of +/- 20 feet were noticed between the surveyed elevation from a HWM on the land surface and the digital elevation model land-surface elevation. Due to these elevation differences, we incorporated a second method of interpolating the water-surface layer. The recorded height above ground value from the surveyed HWM was added to the digital elevation model land-surface elevation at that point. This created a new water-surface elevation value to be used with the “Topo to Raster” interpolation method to create a second depth raster, "depth_dem". Both sets of inundation layers are provided.
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TwitterThe mapped area boundary, flood inundation extents, and depth rasters were created to provide an estimated extent of flood inundation along the Greenbrier River within the community of Ronceverte, West Virginia. These geospatial data include the following items: 1. greenbrier_ron_bnd; shapefile containing the polygon showing the mapped area boundary for the Greenbrier River flood maps, 2. greenbrier_ron_hwm; shapefile containing high-water mark points, 3. polygon_greenbrier_ron_hwm; shapefile containing mapped extent of flood inundation, derived from the water-surface elevation surveyed at high-water marks, 4. depth_hwm; raster file for the flood depths derived from the water-surface elevation surveyed at high-water marks, 5. polygon_greenbrier_ron_dem; shapefile containing mapped extent of flood inundation, derived from the height above ground recorded at high-water marks and the digital elevation model (DEM) raster, 6. depth_dem; raster file for the flood depths derived from the height above ground recorded at high-water marks and the digital elevation model raster. The upstream and downstream mapped area extent is limited to the upstream-most and downstream-most high-water mark locations. In areas of uncertainty of flood extent, the mapped area boundary is lined up with the flood inundation polygon extent. The mapped area boundary polygon was used to extract the final flood inundation polygon and depth raster from the water-surface elevation raster file. Depth raster files were created using the "Topo to Raster" tool in ArcMap (ESRI, 2012). For this study two sets of inundation layers were generated for each reach. One raster file showing flood depths, "depth_hwm", was created by using high-water mark water-surface elevation values on the land surface and a digital elevation model. However, differences in elevation between the surveyed water-surface elevation values at HWM’s and the land-surface elevation from the digital elevation model data provided uncertainty in the inundation extent of the generated layers. Often times elevation differences of +/- 20 feet were noticed between the surveyed elevation from a HWM on the land surface and the digital elevation model land-surface elevation. Due to these elevation differences, we incorporated a second method of interpolating the water-surface layer. The recorded height above ground value from the surveyed HWM was added to the digital elevation model land-surface elevation at that point. This created a new water-surface elevation value to be used with the “Topo to Raster” interpolation method to create a second depth raster, "depth_dem". Both sets of inundation layers are provided.
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TwitterTax District Boundaries: Official tax district boundary lines adopted by the WV Legislature in 1978 as a general reference to delineate rural tax district boundaries. The boundaries were drawn from 1:24,000-scale USGS topographic maps in 1978 and coincide with county magisterial districts as of July 1, 1973. Unlike magisterial districts that are realigned every ten years following the census, the tax district boundary does not follow equal representation requirements. In 1978 the West Virginia Geologic and Economical Survey published six 1:500,000-scale maps delineating official county and tax district boundary lines for the State. In 1996 the West Virginia Department of Tax and Revenue, Property Tax Division, converted the 1978 source maps into a digital format and added descriptive attributes for each tax district. In October of 2003, the WV GIS Technical Center appended 24K DLG boundary files and lines drawn from 24K DRGs into a statewide 24K Tax District Boundary dataset. In 2017, WVGISTC has appended this file with parcel data or Census Populated Places boundaries for missing tax districts.
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TwitterThe mapped area boundary, flood inundation extents, and depth rasters were created to provide an estimated extent of flood inundation along the Greenbrier River within the community of Alderson, West Virginia. These geospatial data include the following items: 1. greenbrier_ald_bnd; shapefile containing the polygon showing the mapped area boundary for the Greenbrier River flood maps, 2. greenbrier_ald_hwm; shapefile containing high-water mark points, 3. polygon_greenbrier_ald_hwm; shapefile containing mapped extent of flood inundation, derived from the water-surface elevation surveyed at high-water marks, 4. depth_hwm; raster file for the flood depths derived from the water-surface elevation surveyed at high-water marks, 5. polygon_greenbrier_ald_dem; shapefile containing mapped extent of flood inundation, derived from the height above ground recorded at high-water marks and the digital elevation model (DEM) raster, 6. depth_dem; raster file for the flood depths derived from the height above ground recorded at high-water marks and the digital elevation model raster. The upstream and downstream mapped area extent is limited to the upstream-most and downstream-most high-water mark locations. In areas of uncertainty of flood extent, the mapped area boundary is lined up with the flood inundation polygon extent. The mapped area boundary polygon was used to extract the final flood inundation polygon and depth raster from the water-surface elevation raster file. Depth raster files were created using the "Topo to Raster" tool in ArcMap (ESRI, 2012). For this study two sets of inundation layers were generated for each reach. One raster file showing flood depths, "depth_hwm", was created by using high-water mark water-surface elevation values on the land surface and a digital elevation model. However, differences in elevation between the surveyed water-surface elevation values at HWM’s and the land-surface elevation from the digital elevation model data provided uncertainty in the inundation extent of the generated layers. Often times elevation differences of +/- 20 feet were noticed between the surveyed elevation from a HWM on the land surface and the digital elevation model land-surface elevation. Due to these elevation differences, we incorporated a second method of interpolating the water-surface layer. The recorded height above ground value from the surveyed HWM was added to the digital elevation model land-surface elevation at that point. This created a new water-surface elevation value to be used with the “Topo to Raster” interpolation method to create a second depth raster, "depth_dem". Both sets of inundation layers are provided.
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TwitterThe mapped area boundary, flood inundation extents, and depth rasters were created to provide an estimated extent of flood inundation along the Howard Creek within the communities of White Sulphur Springs and Caldwell, West Virginia. These geospatial data include the following items: 1. howard_bnd; shapefile containing the polygon showing the mapped area boundary for the Howard Creek flood maps, 2. howard_hwm; shapefile containing high-water mark points, 3. polygon_howard_hwm; shapefile containing mapped extent of flood inundation, derived from the water-surface elevation surveyed at high-water marks, 4. depth_hwm; raster file for the flood depths derived from the water-surface elevation surveyed at high-water marks, 5. polygon_howard_dem; shapefile containing mapped extent of flood inundation, derived from the height above ground recorded at high-water marks and the digital elevation model (DEM) raster, 6. depth_dem; raster file for the flood depths derived from the height above ground recorded at high-water marks and the digital elevation model raster. The upstream and downstream mapped area extent is limited to the upstream-most and downstream-most high-water mark locations. In areas of uncertainty of flood extent, the mapped area boundary is lined up with the flood inundation polygon extent. The mapped area boundary polygon was used to extract the final flood inundation polygon and depth raster from the water-surface elevation raster file. Depth raster files were created using the "Topo to Raster" tool in ArcMap (ESRI, 2012). For this study two sets of inundation layers were generated for each reach. One raster file showing flood depths, "depth_hwm", was created by using high-water mark water-surface elevation values on the land surface and a digital elevation model. However, differences in elevation between the surveyed water-surface elevation values at HWM’s and the land-surface elevation from the digital elevation model data provided uncertainty in the inundation extent of the generated layers. Often times elevation differences of +/- 20 feet were noticed between the surveyed elevation from a HWM on the land surface and the digital elevation model land-surface elevation. Due to these elevation differences, we incorporated a second method of interpolating the water-surface layer. The recorded height above ground value from the surveyed HWM was added to the digital elevation model land-surface elevation at that point. This created a new water-surface elevation value to be used with the “Topo to Raster” interpolation method to create a second depth raster, "depth_dem". Both sets of inundation layers are provided.
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TwitterFrom the site: “A Digital Raster Graphic (DRG) is a scanned image of a U.S. Geological Survey (USGS) topographic map. An unclipped scanned image includes all marginal information, while a clipped or seamless scanned image clips off the collar information. DRGs may be used as a source or background layer in a geographic information system, as a means to perform quality assurance on other digital products, and as a source for the collection and revision of digital line graph data. The DRGs also can be merged with other digital data (e.g., digital elevation model or digital orthophotoquad data), to produce a hybrid digital file.
The output resolution of a DRG varies from 250 to 500 dots per inch. The horizontal positional accuracy of the DRG matches the accuracy of the published source map. To be consistent with other USGS digital data, the image is cast on the UTM projection, and therefore, will not always be consistent with the credit note on the image collar. Only the area inside the map neatline is georeferenced, so minor distortion of the text may occur in the map collar. Refer to the scanned map collar or online Map List for the currentness of the DRG.”