This digital geospatial data set consists of saturated-thickness contours that were generated with a Geographic Information System (GIS). The U.S. Geological Survey developed this data set as part of a project that is presented in the report, Geohydrology of the shallow aquifers in the Denver metropolitan area, Colorado (Robson, 1996).
This data set was created by the U.S. Geological Survey (USGS) in the development of USGS Hydrologic Investigations Atlas HA-736 (Robson, 1996). This data set was used in the creation of a 1:50,000-scale contour map.
Procedures_Used Using ARC/INFO software, USGS 7.5-minute Digital Elevation Models (DEMs) that encompass the study area were converted to raster surface formats (grids, in ARC/INFO terminology) with the command DEMLATTICE. They were mosaicked into a single continuous surface using the ARC/INFO GRID function, MERGE, and projected into an appropriate coordinate system using the ARC/INFO command, PROJECT. The grid then was smoothed using an averaging filter with a radius of 9 grid cells (180 meters): Grid: lsdcir9 = focalmean (all_lsd7spc, circle, 9, data) Contour data sets (coverages, in ARC/INFO terminology) of water- level altitude and unconsolidated-sediment thickness (documented separately) were converted to grids with the same cell size as that of the DEM-derived grid (approximately 30-meter spacing between points). Arc: createtin wttin3 30 30 Createtin: cover watertable2 line contour 1 Createtin: cover wtpts point contour 1 Createtin: end Arc: tinlattice wttin3 wtgrd3 quintic Arc: createtin obtin2 # 30 Createtin: cover all_obsup line contour 1 Createtin: cover overburden line contour 1 Createtin: cover outcrop4 poly 5 Createtin: end Arc: tinlattice obtin2 obgrd2 quintic The unconsolidated-sediment-thickness grid was subtracted from the land-surface-altitude grid to produce a bedrock-surface-altitude grid. Grid: bdrkgrd = lsdcir9 - obgrd2 A saturated-thickness grid resulted from the subtraction of the bedrock-altitude grid from the water-level-altitude grid. Before the contouring process, the saturated-thickness grid was processed to remove values less than or equal to -10 feet. Grid: satgrd5 = wtgrd3 - bdrkgrd Grid: satgrd5a = select (satgrd5, value ge -10) A saturated-thickness contour coverage was generated by the software at an interval of 20 feet. Arc: latticecontour satgrd5a satcnt5a 20 0 contour 20 Manual editing corrected contours that were not appropriately interpolated as determined by consultation with the projects author. The coverage was built with line topology. The coverage then was clipped with a coverage of an outline that delimited the extent of 20-foot-interval water-level contours. Contour "islands" with a perimeter length of 1,000 meters or less were removed from the coverage in ARCEDIT. The jagged appearance of the contours was addressed by smoothing the contours in an editing session. Arc vertex grain tolerances (the minimum allowable distance between vertices in a line) were set to 90 meters, all the arcs were generalized with the Arcedit command, SPLINE, and the grain tolerances were reset to 30 meters before splining the arcs again. After initial colleague reviews, the coverage was processed to support polygon topology. First, the clipping coverage that was used to produce the line coverage was added to the line coverage itself in an ARCEDIT session. The resultant coverage was further edited to connect all contours to the clipping outline. The coverage then was built with polygon topology. Contours with thickness values equal to zero were removed from the coverage, and polygon topology was recreated. Polygon item "RANGE" was added to the polygon attribute table of the coverage. After labels were created for the polygon coverage, the coverage was attributed for "RANGE" values in ARCEDIT. The final coverage is intended to be used as one thematic layer in maps to be published at a scale of 1:50,000. Revisions Rev 1, 11/17/94, original data set. Reviews_Applied July-August 1994: Colleague review of 1:50,000-scale maps that were generated from the original data set. Manuscript review included validation of method as outlined in map report and inspection for positional accuracy. January-Febuary 1996: Colleague review of original digital data set and associated metadata. Metadata review included verification of table and column/item identities and definitions, validation of the reference data sets and citations, verification of consistency between log file and documented procedures, and validation of development method as described in the documentation. March 1996: Inspection of 1:50,000-scale hardcopy generated from this data set. Related_Spatial_and_Tabular_Data_Sets None. Other_References_Cited Robson, S.G., 1996, Geohydrology of the shallow aquifers in the Denver metropolitan area, Colorado: U.S. Geological Survey Hydrologic Investigations Atlas HA-736, 5 sheets, scale 1:50,000. Notes Char, Stephen J., Sieverling, Jennifer B., and Miller, L. Lee, 1996, Digital geospatial data sets used in the study of geohydrology of the shallow aquifers in the Denver metro- politan area, Colorado: a)Bedrock outcrop, b)Unconsolidated- sediment thickness, c)Water-table altitude, d)Bedrock- surface altitude, e)Depth to water, and f)Saturated-zone thickness: U.S. Geological Survey Open-File Report 96-659. Any use of trade, product or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this metadata file is designed to conform to the Federal Geographic Data Committee Spatial Metadata Content Standard, these data and this metadata file were developed using ARC/INFO software; therefore, this file includes ARC/INFO-specific terminology. Data used to develop this project were obtained from many sources, including the following: Cherry Creek Valley Water and Sanitation District City of Brighton Colorado Department of Health Colorado Department of Highways Colorado State Engineers Office Cooley Sand and Gravel Denver Federal Center Denver Water Department EG&G Rocky Flats Incorporated Environmental Protection Agency (Superfund) Frei & Sons (Sand and Gravel) HRS Consultants Lowry Air force Base Metro Denver Wastewater Reclamation District Public Service Company Rocky Mountain Arsenal U.S. Army Corps of Engineers Urban Drainage and Flood Control Western Mobile Incorporated
publication date
This data set should not be used at a scale larger than 1:50,000.
Box 25046, MS 415, Denver Federal Center
U.S. Army--Rocky Mountain Arsenal U.S. Department of Energy--Rocky Flats Field Office Colorado Department of Public Health and Environment Colorado Department of Natural Resources--State Engineers Office Denver Water Department Littleton-Englewood Wastewater Treatment Plant East Cherry Creek Valley Water and Sanitation District Metro Wastewater Reclamation District Willows Water District Cities of Aurora, Lakewood, and Thornton
See Entity_Attribute_Information
Attribute accuracy is described, where present, with each attribute defined in the Entity and Attribute Section.
Polygon and chain-node topology present.
The DEM-derived input data set was smoothed with a circular filter of a 9-cell-length (180-meter) radius. After the data set was smoothed, it matched more closely the apparent resolution of the water-table data set. The final saturated-thickness contour data set would have been too convolute (implying more detail than was supportable by the water table data set) if it had been produced using an unfiltered DEM-derived data set. The contours that comprise three of the input data sets (overburden, all_obsup, and watertable2) were digitized by hand at a scale of 1:24,000 from hand-drawn maps. The hand-drawn contours for overburden and watertable2 were interpolated at 20-foot intervals using data from wells whose locations were reported in Public Land Survey System coordinates. The well locations are theoretically accurate to the nearest quarter-quarter-quarter-quarter section, but they were not field-checked for accuracy. Also, the well locations were not evenly distributed throughout the study area. The limited number of supplemental hand-drawn contours that comprise all_obsup were interpolated at 10-foot intervals and were intended to enhance the surface interpolation in areas where the CREATETIN session failed to accurately represent the unconsolidated-sediment- thickness surface. The bedrock-outcrop outlines that comprise another input data set also were digitized by hand at a scale of 1:24,000 from hand-drawn maps. The hand-drawn outlines were not field-checked for accuracy.
The DEM-derived input data set was smoothed with a circular filter of a 9-cell-length (180-meter) radius. After the data set was smoothed, it matched more closely the apparent resolution of the water table data set. The final saturated-thickness contour data set would have been too convolute (implying more detail than was supportable by the water table data set) if it had been produced using an unfiltered DEM-derived data set. The contours that comprise three of the input data sets (overburden, all_obsup, and watertable2) were digitized by hand at a scale of 1:24,000 from hand-drawn maps. The hand-drawn contours for overburden and watertable2 were interpolated at 20-foot intervals using data from wells whose locations were reported in Public Land Survey System coordinates. The well locations are theoretically accurate to the nearest quarter-quarter-quarter-quarter section, but they were not field-checked for accuracy. Also, the well locations were not evenly distributed throughout the study area. The limited number of supplemental hand-drawn contours that comprise all_obsup were interpolated at 10-foot intervals and were intended to enhance the surface interpolation in areas where the CREATETIN session failed to accurately represent the unconsolidated-sediment- thickness surface. The bedrock-outcrop outlines that comprise another input data set also were digitized by hand at a scale of 1:24,000 from hand-drawn maps. The hand-drawn outlines were not field-checked for accuracy.
See Supplemental_Information for overview
SJCHAR LATTICECONTOUR SATGRD96_1B1 SATCNT96_1B1 20 0 CONTOUR 1
SJCHAR RESELECT SATCNT96_1B1 SATCNT96_1B1A LINE # LINE
SJCHAR CLIP SATCNT96_1B1A /GIS/USERS/ROBSON/FINALS/CI_EXT20 SATZN96 LINE .001
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/SATZN96
SJCHAR SMALL ISLANDS REMOVED, EDGE/SLIVER ARCS REMOVED
SJCHAR GRAIN 90
SJCHAR 'SPLINE;GRAIN 30; SPLINE;GET CI_EXT20'
SJCHAR BUILD SATZN96A POLY
SJCHAR ADDITEM SATZN96A.PAT SATZN96A.PAT RANGE 3 3 I
SJCHAR CREATELABELS SATZN96A
SJCHAR BUILD SATZN96A POLY
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/SATZN96A
SJCHAR BUILD SATZN96A POLY
SJCHAR CREATELABELS SATZN96A 0
SJCHAR IDEDIT SATZN96A POLY
SJCHAR IDEDIT SATZN96A POLY
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/SATZN96A
SJCHAR RESTOREARCEDIT SATZN96A SATZN96ARES
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/SATZN96B
SJCHAR BUILD SATZN96B POLY
SJCHAR REMOVED INTERNAL POLYGONS NEAR ARVADA
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/SATZN96B
SJCHAR MORE POLYGON ATTRIBUTING (ITEM RANGE)
SJCHAR BUILD SATZN96B POLY
SJCHAR LABELERRORS SATZN96B
SJCHAR CREATELABELS SATZN96B 0
SJCHAR IDEDIT SATZN96B
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/SATZN96B
JBSIEVER LABELERRORS /WORK/GIS1WORK2/ROBSON/SATZN96B
SJCHAR ARCEDIT /WORK/GIS1WORK2/ROBSON/SATZN96B
SJCHAR BUILD /WORK/GIS1WORK2/ROBSON/SATZN96B POLY
SJCHAR ELIMINATED MOST EGREGIOUS SPIKES WITH VERTEX COMMANDS
JBSIEVER LABELERRORS /WORK/GIS1WORK2/ROBSON/SATZN96B
SJCHAR EXPORT COVER /WORK/GIS1WORK2/ROBSON/SATZN96B SATZN96B
SJCHAR DOCUMENT SATZN96B CREATE SJCHAR
SJCHAR DOCUMENT SATZN96B UPDATE SJCHAR
SJCHAR DOCUMENT SATZN96B UPDATE SJCHAR
SJCHAR DOCUMENT SATZN96B UPDATE SJCHAR
SJCHAR DOCUMENT SATZN96B UPDATE SJCHAR
SJCHAR RENAME SATZN96B SATTHICK
SJCHAR DOCUMENT SATTHICK UPDATE SJCHAR
SJCHAR DOCUMENT SATTHICK UPDATE SJCHAR
SJCHAR COPY /WORK/GIS1WORK2/ROBSON/SATTHICK SATTHICK
SJCHAR DOCUMENT SATTHICK UPDATE SJCHAR
SJCHAR EXPORT COVER SATTHICK SATTHICK
SJCHAR EXPORT COVER SATTHICK SATTHICK
Area of poly/region in square coverage units
Computed
Perimeter of poly/region in coverage units
Computed
Internal feature number
Computed
User-assigned feature number
User-defined
Saturated-thickness range key
U.S. Geological Survey
Internal number of from-node
Computed
Internal number of to-node
Computed
Internal number of poly to left of arc
Computed
Internal number of poly to right of arc
Computed
Length of arc in coverage units
Computed
Internal feature number
Computed
User-assigned feature number
User-defined
Saturated-thickness value, in feet
U.S. Geological Survey
Arc attribute "CONTOUR" is the thickness of the saturated zone in feet. Polygon attribute "RANGE" is a key for plotting the saturated- thickness range of the polygon feature. The actual range is equal to the range value in feet, plus or minus 10 feet.
Not Available
Box 25046, MS 415, Denver Federal Center
Although this data set has been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data and related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of this data, software, or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Saturated thickness contours geographic features
Saturated thickness contours geographic features
ArcIMS Image Map Service
A web-based interactive mapping system that accesses an ArcIMS Map Service running on certmapper.cr.usgs.gov.
Topological Vector Profile
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