Chemistry and toxicity of urban sediments, Maricopa County, Arizona, data and summary statistics
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Open-File Report↗
Geology topics
J. T. Parker
Publications and source records attributed to J. T. Parker.
Channel change and sediment transport in two desert streams in central Arizona, 1991-92
Channel change and suspended-sediment transport were monitored in the Salt and Hassayampa Rivers in Maricopa County, Arizona, during the winter and summer rainy seasons of 1991-92. Flows were moderate. Results illustrate the high instability of these channels and high variability of process and response. A channelized, gravel-paved reach of the Salt River in an industrial part of Phoenix was incised 2 meters by sustained winter flows from upstream reservoir releases that had a peak discharge of 368 cubic meters per second. Similar amounts of channel incision occurred at bridge crossings at four other locations within 20 kilometers upstream from the study reach at 16th Street. Channel incision changed the stage-discharge relation at the streamflow-gaging station at 24th Street. Bank erosion below 16th Street undermined bank revetment and caused a large concrete-drop structure at the mouth of a storm drain to fall into the channel. About 23 kilometers upstream from the study area, bank erosion on the Salt River exhumed a landfill that resulted in entrainment and transport of refuse. The flows, which lasted 5 months beginning in early January, produced the highest peak discharge in 9 years on the normally dry lower Salt River. The flows were minor, however, compared to peak discharges that occurred during a series of floods from 1966 to 1980. The flood of 1980 that had a peak discharge of 5,100 cubic meters per second was the largest since 1905. In August 1992, several days of flows from reservoir releases produced a higher peak discharge of 493 cubic meters per second that resulted in little or no channel change. On a sandy, ephemeral reach of the Hassayampa River in rural Maricopa County west of Phoenix, as much as 20 meters of bank erosion resulted from three flows of short duration and low-to-moderate peak discharge. Most bank erosion resulted from a winter flow that lasted about 7 hours, had a peak discharge of 127 cubic meters per second, and an estimated recurrence interval of less than 5 years. A summer flow that lasted 3 hours had a peak discharge of 173 cubic meters per second and caused some bank erosion and possibly some dissection of terraces. The magnitude of change, however, was far less than that of the winter flow. Suspended-sediment concentration on the Salt River during the winter flows was typical of those for other regulated streams in Arizona and ranged from 2 to 617 milligrams per liter at discharges from 6.7 to 343 cubic meters per second. Fine-grained sediments in the channel bottom probably were the main source of sediment transported in suspension. During periods of prolonged, steady flows, suspended-sediment concentration tended to decline, which indicated a probable depletion of sediment supply. On the Hassayampa River, suspended-sediment concentrations ranged from 12,800 to 132,000 milligrams per liter at discharges of 13 to 128 cubic meters per second. The relation of sediment concentration to discharge was poor for the entire set of samples, but a clear pattern was evident for each period of storm runoff. In two of three periods of runoff sampled, maximum suspended-sediment concentration occurred just before peak discharge and declined rapidly.
Water-Resources Investigations Report↗
Channel change on the Santa Cruz River, Pima County, Arizona, 1936-86
The Santa Cruz River, an ephemeral river that drains 8,581 square miles in southeastern Arizona, has a long history of channel instability. Since the late 19th century, lateral channel erosion has caused extensive property damage, particularly in Pima County. During the flood of 1983, about $100 million damage was caused in the Tucson area alone; most damage resulted from bank erosion on the Santa Cruz River and its tributaries. The nature, magni- tude, location, and frequency of channel change on the Santa Cruz River were highly variable in time and space from 1936 through 1986 along a 70-mile reach in Pima County, Arizona. Four mechanisms of lateral channel change--channel migration, avulsion and meander cutoff, channel widening, and arroyo widening--were identified on the Santa Cruz River. The dominant mechanism in a reach depends on channel morphology and flood magnitude. The dominant vertical change has been degradation. The timing and magnitude of channel change at a particular location are controlled primarily by hydroclimatic factors such as magnitude, duration, intensity, and frequency of precipitation and floods. The location of channel change and its magnitude in response to a given discharge are controlled largely by topographic, geologic, hydraulic, and artificial factors. Although much of the present morphology of the Santa Cruz River is the result of recent large floods, a direct link between hydroclimatic con- ditions and channel change is not always evident because resistance of the channel to erosion varies with time. (USGS)
Arizona↗