This digital geospatial data set consists of digitized water-table-altitude contours that were manually drawn at an interval of 20 feet. 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. It also was used as an input source for the automated generation of a water-table surface that was in turn used to generate an unsaturated-thickness surface, also contoured for use in a 1:50,000-scale map.
Procedures_Used Water-level-altitude data from well logs (see "Notes" section) were manually plotted and contoured onto mylar overlays of 20 paper USGS 7.5-minute topographic series quadrangle maps that encompass the Denver metropolitan area. These maps were the Arvada, Box Elder School, Brighton, Commerce City, Coal Creek, Eastlake, Englewood, Fitzsimons, Fort Logan, Golden, Highlands Ranch, Indian Hills, Lafayette, Littleton, Louisville, Mile High Lakes, Morrison, Parker, Piney Creek, and Sable quadrangles. The contours from these maps were digitized into 20 corresponding geospatial data sets, known as coverages in ARC/INFO terminology. The coverages were in the polyconic projection specific to each quadrangle: the central meridian was the longitude of the center of the quadrangle, and the latitude of the origin was the latitude of the bottom of the quadrangle. Registration root mean square errors of 0.008 inches or less were acceptable for the digitization process. Drafts of these coverages were then plotted at a scale of 1:24,000, checked against the original mylar overlays, and corrected for omissions and locational errors. Arc items "CONTOUR" and "DASH" were added to the arc attribute table of the coverage and manually attributed in Arcedit, using the original manuscript mylars for references. The coverages were then projected into a common state plane projection and edgematched. The northern and eastern areas of each coverage were edgematched when necessary. The northern edge of a coverage was adjusted to fit the southern edge of a coverage adjacent to the north; the eastern edge of a coverage was adjusted to fit the western edge of a coverage adjacent to the east. The coverages were appended into a single coverage that was then cleaned with an arc dangle tolerance of 12.192 feet and a fuzzy tolerance of 1.2192 feet. The coverage was built with polygon topology. The coverage was plotted at 1:50,000, checked, and corrected. Arc item "TEXTKEY," was added to the arc attribute table of the coverage and manually attributed in Arcedit, using hardcopy and base map overlays for references. The last two digits of item "CONTOUR" were redefined in INFO to be item "INDEXKEY." The final coverage is intended to be used as one thematic layer in a map to be published at a scale of 1:50,000. Revisions Revision 1.0, August 1996, 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
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
Attribute accuracy is described, where present, with each attribute defined in the Entity and Attribute Section
Chain-node topology present.
The contours that comprise this data set were digitized by hand from hand-drawn maps. The hand-drawn contours were interpolated 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. However, the wells were not evenly distributed throughout the study area, nor were their locations field-verified.
Resolution as reported
The contours that represent the vertical information in this data set were digitized by hand from hand-drawn maps. The hand-drawn contours were interpolated using water-level data from wells that were not evenly distributed throughout the study area. Water-level data were measured in different seasons in different years.
See Supplemental_Information for overview
APPEND ALL_WTSPC LINE
CLEAN ALL_WTSPC ALL_WTSPC2CL 24.384 2.4384 LINE
ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/ALL_WTSPC2CL
BUILD ALL_WTSPC2CL LINE
ARCEDIT ALL_WT
ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/ALL_WT
RESTOREARCEDIT ALL_WT ALL_WTR
ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/ALL_WT
ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/ALL_WT
ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/ALL_WT
BUILD ALL_WT LINE
BUILD ALL_WT LINE
ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/ALL_WT
BUILD ALL_WT LINE
ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/ALL_WT
ARCEDIT WATERTABLE
ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/WATERTABLE
ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/WATERTABLE
ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/WATERTABLE
BUILD WATERTABLE LINE
ARCEDIT WATERTABLE2
ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/WATERTABLE2
BUILD WATERTABLE2 LINE
SJCHAR ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/WATERTABLE2
SJCHAR RESTOREARCEDIT WATERTABLE2
SJCHAR ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/WATERTABLE2
SJCHAR ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/WATERTABLE2
SJCHAR BUILD WATERTABLE2 LINE
SJCHAR EDITING (FEB 96) BASED ON COMMENTS FROM COLLEAGUE REVIEW
JBSIEVER ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/WATERTABLE2
JBSIEVER AE
JBSIEVER ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/WATERTABLE2
JBSIEVER ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/WATERTABLE2
JBSIEVER ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/WATERTABLE2
JBSIEVER ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/WATERTABLE2
JBSIEVER INDEX WATERTABLE2
JBSIEVER ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/WATERTABLE2
JBSIEVER ARCEDIT /GIS/USERS/ROBSON/WATERTABLE/WATERTABLE2
SJCHAR DOCUMENT WATERTABLE2 CREATE SJCHAR
SJCHAR DOCUMENT WATERTABLE2 UPDATE SJCHAR
SJCHAR DOCUMENT WATERTABLE2 UPDATE SJCHAR
SJCHAR DOCUMENT WATERTABLE2 UPDATE SJCHAR
SJCHAR DOCUMENT WATERTABLE2 UPDATE SJCHAR
SJCHAR DOCUMENT WATERTABLE2 UPDATE SJCHAR
SJCHAR DOCUMENT WATERTABLE2 UPDATE SJCHAR
SJCHAR RENAME WATERTABLE2 WATERTABLE
SJCHAR RENAME WATERTABLE WATERTBL
SJCHAR DOCUMENT WATERTBL UPDATE SJCHAR
SJCHAR DOCUMENT WATERTBL UPDATE SJCHAR
SJCHAR COPY /GIS/USERS/ROBSON/WATERTABLE/WATERTBL WATERTBL
SJCHAR DOCUMENT WATERTBL UPDATE SJCHAR
SJCHAR EXPORT COVER WATERTBL WATERTBL
SJCHAR BUILD WATERTBL LINE
SJCHAR EXPORT COVER WATERTBL WATERTBL
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
Water level altitude, in feet above sea level
U.S. Geological Survey
One-character-wide key used in line plotting
U.S. Geological Survey
Key used in text plotting (please see Supplemental Information)
U.S. Geological Survey
Last two digits of item CONTOUR, used to delineate index contours
U.S. Geological Survey
Arc attribute "CONTOUR" is the water-level altitude in feet above sea level. Arc attribute "DASH" indicates line symbol type (dash or solid) intended for use in plotting the illustration. Dashed contour locations are less accurate. Arc attribute "TEXTKEY" indicates how contour values are drawn in a plotting routine: B = no text. L = text above line lc. U = text below uc. P = text using point2 blank. S = text using LINE blank. G = text using point2 blank gray mask. Arc attribute "INDEXKEY" delineates between 100-foot index contours and non-index contours in a plotting routine. Its values are the character equivalent of the last two digits in item "CONTOUR."
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.
Hydrogeologic contours geographic features
Hydrogeologic 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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