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<br />Hassayampa River near Morristown <br /> <br />Reach location: <br /> <br />Latitude 33053'06", longitude 112039'41". Reach is at streamflow-gaging station <br />09516500, Hassayampa River near Morristown. <br /> <br />796 mi2. <br /> <br />Drainal!e area: <br /> <br />Bed-material size: <br />Channel descriution: <br /> <br />d50 = 0.42 mm (0.0014 ft). <br /> <br />The channel bed in the reach consists of sand-sized material, and the channel is <br />straight and uniform. The right bank is a straight vertical railway embankment, and <br />the left bank is a vertical bedrock cliff. The sparse vegetation is mainly mesquite <br />along the right bank. The stream is intermittent, and flow is unregulated. <br /> <br />Remarks: <br /> <br />Data from current-meter measurements were used to obtain an accurate <br />representation of the bed configuration. This technique was required because the bed <br />is highly unstable and may take on different configurations during moderate to high <br />flows (fig. 9A). Only channel-geometry measurements obtained during flow from <br />this one section, therefore, were used for the n-verification computations. The <br />measured water-surface slope is assumed to approximate the slope of the energy- <br />gradient line. Uniformity of the reach probably prevents significant energy losses <br />due to expansion and contraction. Potential errors incurred by the required <br />assumptions probably are offset by the accurate measurements of the channel <br />configuration during flows on this highly unstable bed. Upper-regime flow <br />conditions were encountered during all of the verification measurements (fig. 3). <br />Plane-bed or nearly plane-bed conditions were reported for the two lower flow <br />measurements, and waves that slowly propagated downstream, nearly extended <br />bank to bank, and periodically collapsed were observed during the two high-flow <br />measurements. Increased suspended-sediment concentrations and turbulance <br />generated by the waves probably resulted in the larger verified n values. The <br />suspended-sediment concentration was 18,916 mg/L at a flow rate of about <br />9,000 ft3/s on March 6, 1995. <br /> <br />Table 11. Flow data and computed roughness coefficients, Hassayampa River near Morristown <br /> <br />Date of flow Discharge, in cubic feet per second Roughness coefficient Rating <br />02-20-93 7.330 0.Q25 Estimate <br />02-09-93 6,180 .026 Estimate <br />01-19-93 2,470 .019 Estimate <br />01-21-93 787 .018 Estimate <br /> <br />Hassaympa River near Morristown 35 <br />