Depth to water (depth2wts - see Supplemental Information for a complete citation)

Abstract:

This digital geospatial data set consists of depth-to-water
(unsaturated-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).

Purpose:

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 to create a 1:50,000-scale
map.

Supplemental_Information:

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
with the Arc/INFO GRID command, MERGE, and projected into an
appropriate coordinate system using the command, PROJECT.  The
grid was then smoothed using an averaging filter with a radius of
9 grid cells (180 meters):

Grid: lsdcir9 = focalmean (all_lsd7spc,circle,9,data)

A contour data set (coverage, in ARC/INFO terminology) of water-
table altitude (documented separately) was converted to a grid
with the same cell size as the DEM-derived data (approximately
30-meter spacing between data points).

Arc:createtin wttin3 30 30
All Rights Reserved Worldwide.
CREATETIN Version 6.1.1(December 23, 1992)

Createtin:cover watertable2 line contour 1
Createtin:cover wtpts point contour 1
Createtin:end
Loading arcs from coverage watertable2...
Weed tolerance 30.000, input arc points 182669,remaining 62545...
Loading points from coverage wtpts...
Proximal tolerance set to 30.000...
Removing points within tolerance...
Within tolerance 12943. Remaining 49679...
Creating TIN...
Writing TIN data structures...

Arc:tinlattice wttin3 wtgrd3 quintic
Converting tin wttin3 to quintic lattice wtgrd3...

TIN boundary

Xmin = 630971.000Ymin = 192412.063
Xmax = 676910.625Ymax = 240848.578
X-extent= 45939.625Y-extent= 48436.516

Lattice parameter input
------------------------
Enter lattice origin  :630910.800 185004.800
Enter lattice upper-right corner  :684848.000 240905.000
Enter lattice resolution :
Enter distance between lattice mesh points :30.2

Lattice has 1786 points in x, 1852 points in y...
Spacing between mesh points (d) is (30.200)...

Loading TIN data structures...
Loading TIN data structures...Initializing interpolation...
Arc:

The water-table-altitude grid was subtracted from the land-surface-
altitude grid to produce a depth-to-water grid.

Grid: uszgrd5 = /gis/arcwork/temparc/shaqdems/lsdcir9 - ../watertable/wtgrd3

The depth-to-water grid was processed to remove values less than
-20 feet and greater than or equal to 1,000 feet.  Using the
depth-to-water grid, the software generated contours at an interval
of 20 feet to produce the contour coverage of depth to water.

Grid: uszgrd5b = select (uszgrd5, value ge -20 and value lt 1000)
Arc: latticecontour uszgrd5b uszcnt5b 20 0 # 20

Manual editing corrected contours that were not correctly inter-
polated, as determined by consultation with the projects author.
The coverage was built with line topology and clipped with a
coverage of the study area outline.

Arc: clip uszcnt5b1 ../watertable/usz_clipper uszcnt5b1cp line 2.5

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.

Arc items "CNT_INT," "TEXTKEY," and "DEPRESSION" were added to
the coverage arc attribute table for plotting purposes.  Further
editing defined how the arcs would be displayed in a plotting
routine.  Also, arc items "TEXTKEY" and "DEPRESSION" were attributed
in this editing session.  Hardcopy and base map overlays were used
for reference.

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 1.0, 4/17/96, 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

Currentness_Reference:

publication date

Attribute_Accuracy_Report:

See Entity_Attribute_Information

Entity_and_Attribute_Overview:

Arc attribute "CONTOUR" is the depth-to-water value in feet.

Arc attribute "CNT_INT" is the integer equivalent of item "CONTOUR"
for use in plotting depth-to-water values without three decimal
places.

Arc attribute "TEXTKEY" indicates how contour elevation values are
drawn in a plotting routine:
X = no text, no arc drawn.
B = no text.
L = text above line lc.
P = text using point2 blank.
G = text using point2 blank gray mask.

Arc attribute "DEPRESSION" indicates whether or not a line delineates
a depression feature.  Lines that delineate depressions are coded
as "Y"; non-depression features are coded as "N."

Entity_and_Attribute_Detail_Citation:

Not Available

Ordering_Instructions:

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