Table 3. Reservoir elevation at time of
Row 37 of the Landsat World Reference System #2.
Landsat data acquisition.
The data, which were acquired from March
through December 1993 and from February
Acquisition
Reservoir
through August 1995, were purchased from the
Acquisition
time
elevation
date
(GMT)
(ft)
Note
USGS's EROS Data Center through the National
Imagery and Mapping Agency (NIMA). (See
7 Mar 93
17:26
665.86
*
USGS [1998a] and NIMA [1998] for further infor-
31 Mar 93
17:17
655.24
*
mation.) The 1993 scenes were generally clear;
8 Apr 93
17:26
651.68
*
24 Apr 93
17:26
644.22
*
1995 scenes had problems with clouds, and were
10 May 93
17:26
637.75
*
not used in the final area and capacity estimates.
26 May 93
17:26
631.06
*
27 Jun 93
17:26
620.61
C
Digital Line Graph data
29 Jul 93
17:26
612.32
*
DLG data at 1:100,000 scale were downloaded
30 Aug 93
17:26
604.88
*
1 Oct 93
17:26
594.65
C
from the U.S. Geological Survey's Global Land In-
2 Nov 93
17:26
578.51
*
formation System (USGS 1998a) for use in recti-
4 Dec 93
17:25
532.10
A
fying the Landsat data. These are vector data, and
9 Feb 95
17:15
531
E
include hydrography, roads, railroads, and miscel-
13 Mar 95
17:14
607.35
C
laneous transportation layers, digitized from
14 Apr 95
17:12
612.80
C
1:100,000-scale paper maps or from photographs.
16 May 95
17:11
605.18
*
For each layer, the 1:100,000-scale quadrangle map
17 Jun 95
17:10
592.20
C
19 Jul 95
17:08
567.40
*
area is broken into eight 15-minute by 15-minute
20 Aug 95
17:07
530.5
E
sections. Quadrangle names and sections of down-
loaded data are listed in Table 2.
Notes:
* (Linearly) Interpolated staff gage reading.
C Read cfs from chart and adjusted.
Table 2. Downloaded DLG data.
A (*) adjusted by +1.5 ft.
E Estimated.
1:100,000-scale
File name
Sections
quadrangle name
prefix
downloaded
dates previous to the 1993 flood: 1953 and 1985.
Bradshaw Mountains, Arizona
PK4
18
Tables C1 and C2 in Appendix C list these values
Salome, Arizona
PH1
3, 4, 7, 8
for every 2 ft of elevation.
Little Horn Mountains, Arizona
PH3
3, 4, 7, 8
According to the reservoir regulation manual,
Phoenix North, Arizona
PH2
18
Phoenix South, Arizona
PH4
18
the 1953 data were derived from an aerial survey.
Gila Bend, Arizona
AJ2
18
No accuracy information was available for these
Theodore Roosevelt Lake, Arizona
ME1
18
data, but area values are rounded to the nearest 100
Mesa, Arizona
ME3
18
acres, which may give an indication of the accuracy.
Casa Grande, Arizona
TS1
18
The 1985 data are from October 1985. The hori-
Silver Bell Mountains, Arizona
TS3
1, 2, 5, 6
zontal accuracy for this survey is 1 ft per 5000 ft,
and the vertical accuracy is 2.5 ft. The effect of
Horizontal accuracy of the maps from which
this uncertainty on capacity was not indicated.
these data are derived is listed as 0.02 inches at the
scale of the map (approximately 50 m or 167 ft on
1993 ground survey profiles
the ground). The digitization process adds an error
Fifteen profiles across the reservoir were sur-
that is less than or equal to 0.003 inches (approxi-
veyed in 1993 while the reservoir was empty. The
mately 7.6 m or 25 ft on the ground).
profiles consist of 2228 survey points, with easting,
northing, and elevation values for each point.
Reservoir elevation data
These data were supplied by the Los Angeles Dis-
Reservoir elevations, obtained from Los Ange-
trict as an ARC/INFO coverage. Accuracy figures
les District's Reservoir Regulation section, are staff
for the survey were not available.
readings made by the dam tender. Table 3 lists the
reservoir elevations at the times of the Landsat
overpasses.
PROCEDURES
A typical procedure for making remotely sensed
Area and capacity data from previous surveys
data useful for applications consists of three basic
Elevation vs. surface and elevation vs. capacity
steps:
information from surveys was available for two
4
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