|
<br />after the flood of 1993-seven measurements were
<br />made from cableway-discharge measurements and
<br />two measurements were made from cross-section
<br />surveys at the cableway, which is at the gaging
<br />station (fig. 17).
<br />Cross sections.-Examination ofthe cross-
<br />section data shows that changes to the cross sec-
<br />tion were limited to a range of about 2 ft vertically
<br />for the entire cableway cross section (figs. 17 and
<br />18; table 1). Although the low-flow channel moves
<br />across the cross section, it changes little in shape
<br />and size. The cross sections for February 9, 1993,
<br />and February 20, 1993, indicate that the bed be-
<br />comes more irregular at higher flows. The cross
<br />sections for March 4 and 31, 1993, show that the
<br />channel smoothed out at lower flows. The cross
<br />section for March 31, 1993, shows the channel
<br />scoured after the measurement on March 4
<br />(figs. 17 and 18). The scour probably was a result
<br />of prolonged low flow between 100 and 200 ft3/s
<br />during the period between measurements. The
<br />cross sections of 1995 and 1996 show little change
<br />in cross-sectional area from the survey on
<br />March 31, 1993. Since the initial cross-sectional
<br />measurement on January 19, 1993, channel
<br />changes range from 26 to 73 percent of the cross-
<br />sectional area relative to the reference elevation.
<br />
<br />PZF analysis.- The gaging station has a
<br />long PZF record (fig. 19), and the stage-discharge
<br />relation generally is under channel control.
<br />Typically, the PZF is recorded when low-flow
<br />discharge measurements are made. The number of
<br />PZF measurements at this site, however, is limited
<br />because frequently there is no flow during site
<br />visits. The first record ofPZF is 6.0 ft on
<br />December 12, 1965 (fig. 19). The PZF increased to
<br />6.6 ft on April 22, 1966, and then decreased to
<br />5.12 ft on August 19, 1970, before the flood of
<br />record on September 5, 1970. The next measured
<br />PZF after the flood of 1970 was 4.6 ft on
<br />December 5,1972. After December 25,1972, the
<br />PZF generally increased until it reached 8.0 ft on
<br />April 3, 1984. Since 1984, the PZF slowly
<br />decreased.
<br />
<br />09517000 Hassayampa River near
<br />Arlington, Arizona
<br />
<br />The site is about 3,000 ft upstream from the
<br />continuous streamflow-gaging station,
<br />
<br />Hassayampa River near Arlington, and is immed-
<br />iately downstream from the Southern Pacific
<br />Railroad bridge (fig. I). Monumented cross sec-
<br />tions emplaced and surveyed by Parker (1995)
<br />were resurveyed for the current study. The site has
<br />a drainage area of about 1,471 mi2 at the gaging
<br />station. The river has entrenched into the sur-
<br />rounding alluvial valley fill. The main flow path is
<br />wide and shallow and is composed primarily of
<br />sand, silt, and occasional deposits of gravel.
<br />Within the main channel, there is an unvegetated
<br />low-flow channel. The areas above the low-flow
<br />channel, which probably represents the flood
<br />plain, are covered with scattered saltcedar, palo
<br />verde, and other assorted bushes and shrubs.
<br />Surveyed cross sections.-Although
<br />Parker (1995) originally surveyed 11 cross sec-
<br />tions, only 6 of these cross sections were found
<br />and resurveyed. The resurveyed cross sections are
<br />cross-sections 2 and 4-8 as numbered in Parker
<br />(1995; fig. 20, this report). Since 1992, the cross
<br />sections generally filled with sediment (fig. 20).
<br />Cross sections surveyed in 1991 (parker, 1995)
<br />have been omitted from the graphs because the
<br />changes from 1991 to 1992 were minor compared
<br />with the large changes between the surveys of
<br />1992 and 1997. Relative to the reference elevation,
<br />the cross sections lost between 737 and 1,586 ft2
<br />of cross-sectional area to deposition of sediment.
<br />The greatest depths of fill occurred in the deepest
<br />sections of the cross sections of 1992. The channel
<br />probably filled during the floods in 1993 or 1995
<br />(fig. 21).
<br />
<br />09513800 New River at New River, Arizona
<br />
<br />The discontinued USGS gaging station, New
<br />River at New River, used in this study is 1,000 ft
<br />upstream from the bridge on Interstate 17 (fig. I).
<br />The New River drainage basin is bounded by the
<br />New River Mountains to the north and west and
<br />the New River Mesa to the south and east. The
<br />drainage area at the gaging station (elevation of
<br />1,800 ft) is 83.3 mi2. The channel at the gaging.station has a bedrock control on the right bank and
<br />sand and gravel-size sediments in the channel and
<br />overbank area.
<br />Surveyed cross sections.-Three cross-
<br />section measurements used for this site were from
<br />indirect measurements of discharge in 1967, 1970,
<br />and 1978 (fig. 22). The cross section also was
<br />
<br />26 Determination of Channel Change for Selected Streams, Maricopa County, Arizona
<br />
|