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Julia B. Graf

Publications and source records attributed to Julia B. Graf.

10 recordsLinked to original sources
USGS1997

The Colorado River in Grand Canyon: how fast does it flow?

Opening the jet tubes at Glen Canyon Dam on March 26, 1996, released from Lake Powell a controlled flood of water that traveled down the Colorado River in Grand Canyon. How fast did the water move? How long did it take for water to reach a particular point along the river? The answers to these questions are important because the speed of river water affects the amount of physical and chemical changes, such as warming by sunlight, that the water will undergo as it moves downstream. Also, very fine particles and substances dissolved in the water travel along with the water, and the speed of the water tells us how fast these move downstream.

Arizona↗
USGS1997

Sand-storage changes in the Colorado River downstream from the Paria and Little Colorado rivers, April 1994 to August 1995

Sixty-six cross sections on the Colorado River in 11-kilometer reachesdownstream from the Paria and Little Colorado Rivers were monitoredfrom June 1992 to August 1995 to provide data to evaluate the effectof releases from Glen Canyon Dam on channel-sand storage and fordevelopment of multidimensional flow and sediment-transport models.Most of the network of monumented cross sections was established andfirst measured JuneSeptember 1992. Data collected from June 1992through February 1994 were published in a previous report. Crosssections downstream from the Paria River were remeasured six timesbetween April 1994 and August 1995. Most sections downstream from theLittle Colorado River were remeasured four times in the same timeperiod. Each measurement consisted of 10 passes across the section,and data presented are the mean section and the standard deviationfrom the mean. Measured depths were converted to bed elevations usingwater-surface elevations measured or estimated for each reach. A linemarked at regular intervals was strung across the river between thesection end points and used to provide horizontal-position control. AWilcoxon rank-sum test was applied to the data, and bed-elevationdifferences between successive measurements that were statisticallysignificant at the 5-percent significance level were identified andused to compute the difference in cross-sectional area frommeasurement to measurement. Changes in sand storage computed forselected cross sections are presented. Changes in area at most of theselected cross sections during the period presented in this reportwere smaller than those measured during the period covered bythe previous report. The largest changes over the monitoring periodpresented in this report were measured at section p22 (+115 squaremeters) downstream from the Paria River and at sections lb1 (+209square meters) and lc2 (156 square meters) downstream from theLittle Colorado River. This report presents selected data from themeasurements made from April 1994 through August 1995 in graphicalform and describes the electronic form of the entire data set.

Open-File Report↗
USGS1997

Streamflow and sediment data collected to determine the effects of a controlled flood in March and April 1996 on the Colorado River between Lees Ferry and Diamond Creek, Arizona

An 8-day period of planned release of water at 1,275 cubic meters per second from Glen Canyon Dam in March and April 1996 provided an opportunity to collect data on river stage, streamflow, water chemistry, and sediment transport at discharges above powerplant releases. The U.S. Geological Survey collected data at five streamflow-gaging stations on the mainstem of the Colorado River and four on tributaries during the controlled flood. River-stage data were collected at an additional 29 locations, and suspended-sediment data were collected at 4 of the 5 mainstem streamflow-gaging stations. In addition, measurements of reach-average flow velocity were made using a dye tracer, and water-surface slope was measured in reaches adjacent to three of the streamflow-gaging stations. Sand-storage changes caused by the controlled flood were documented by measuring bed elevation of the channel at cross sections before and after the controlled releases at the network of 120 monumented locations. This report presents selected data in tabular and graphical form. The data presented in the report are available in electronic form.

Open-File Report↗
USGS1996

Streamflow transport of radio-nuclides and other chemical constituents in the Puerco and the Little Colorado River Basins, Arizona and New Mexico

Samples collected at streamflow-gaging stations in the Puerco and Little Colorado rivers show that radioactivity of suspended sediment at gaging stations downstream from inactive uranium mines was not significantly higher than at gaging stations where no mining has occurred upstream. Drinking-water standards for many constituents, however, commonly are exceeded during runoff because concentration of these constituents on sediment from natural processes is high and suspended-sediment loads are high during runoff.

Arizona, New Mexico↗
USGS1990

Aggradation and degradation of alluvial sand deposits, 1965 to 1986, Colorado River, Grand Canyon National Park, Arizona

Alluvial sand deposits along the Colorado River in Grand Canyon National Park are used as campsites and are substrate for vegetation. The largest and most numerous of these deposits are formed in zones of recirculating current that are created downstream from where the channel is constricted by debris fans at tributary mouths. Alluvial sand deposits are classified by location and form. Separation and reattachment deposits are downstream from constrictions within recirculation zones. Separation deposits are near the point of flow separation and typically mantle large debris fans. Reattachment deposits are near the point of flow reattachment and project upstream beneath much of the zone of recirculating current. Upper-pool deposits are upstream from a constriction and are associated with backwaters. Channel-margin deposits line the channel and have the form of terraces. Some are created in small recirculation zones. Reattachment and channel-margin deposits are largest and most numerous in wide reaches, although small channel-margin deposits are used as campsites in the narrow Muav Gorge. Separation deposits are more uniformly distributed throughout Grand Canyon National Park than are other types of deposits. In some narrow reaches where the number of alluvial sand deposits used as campsites is small, separation deposits are a high percentage of the total. During high flows, both separation and reattachment deposits are initially scoured but are subsequently redeposited during flow recession. Sand is also exchanged between the main channel and recirculation zones. The rate of recession of high flows can affect the elevation of alluvial deposits that are left exposed after a flood has passed. Fluctuating flows that follow a period of steady discharge cause initial erosion of separation and reattachment deposits. A part of this eroded sand is transported to the main channel. Therefore, sand is exchanged between the main channel and recirculation zones and redistributed within recirculation zones over a broad range of discharges. Comparison of aerial photographs and reinterpretation of published data concerning changes of alluvial sand deposits following recession of high flows in 1983 and 1984 indicate that sand was eroded from recirculation zones in narrow reaches. In wide reaches, however, aggradation in recirculation zones may have occurred. In narrow reaches, the decrease of reattachment deposits was greater than that of separation deposits. In all reaches, the percentage of separation deposits that maintained a constant area was greater than for other deposits. Separation deposits, therefore, appear to be the most stable of the deposit types. Fluctuating flows between October 1985 and January 1986, which followed the higher and steadier flows of 1983 to 1985, caused erosion throughout the park. For separation deposits, erosion was greatest at those sites where deposition from the 1983 high flows had been greatest. The existing pattern of low campsite availability in narrow reaches and high campsite availability in wide reaches was thus accentuated by the sequence of flows between 1983 and 1985.

Professional Paper↗
USGS1986

Traveltime and longitudinal dispersion in Illinois streams

Twenty-seven measurements of traveltime and longitudinal dispersion in 10 Illinois streams made from 1975 to 1982 provide data needed for estimating traveltime of peak concentration of a conservative solute, traveltime of the leading edge of a solute cloud, peak concentration resulting from injection of a given quantity of solute, and passage time of solute past a given point on a stream. These four variables can be estimated graphically for each stream from distance of travel and either discharge at the downstream end of the reach or flow-duration frequency. From equations developed from field measurements, the traveltime and dispersion characteristics also can be estimated for other unregulated streams in Illinois that have drainage areas less than about 1,500 square miles. For unmeasured streams, traveltime of peak concentration and of the leading edge of the cloud are related to discharge at the downstream end of the reach and to distance of travel. For both measured and unmeasured streams, peak concentration and passage time are best estimated from the relation of each to traveltime. In measured streams, dispersion efficiency is greater than that predicted by Fickian diffusion theory. The rate of decrease in peak concentration with traveltime is about equal to the rate of increase in passage time. Average velocity in a stream reach, given by the velocity of the center of solute mass in that reach, can be estimated from an equation developed from measured values. The equation relates average reach velocity to discharge at the downstream end of the reach. Average reach velocities computed for 9 of the 10 streams from available equations that are based on hydraulic-geometry relations are high relative to measured values. The estimating equation developed from measured velocities provides estimates of average reach velocity that are closer to measured velocities than are those computed using equations developed from hydraulic-geometry relations.

Illinois↗
USGS1983

Measurement of bedload discharge in nine Illinois streams with the Helley-Smith sampler

Samples collected with the Helley-Smith bedload sampler provide useful information about transport of sand-size sediment in Illinois streams. Samples provide the basis for bedload-discharge rating curves for the Rock and Kaskaskie Rivers and Henderson Creek. Comparison of measured bedload discharge with bedload discharge computed for selected flow conditions from channel characteristics allows the selection of an appropriate indirect method for determining bedload discharge for the Spoon, Kishwaukee, and Edwards Rivers. No one indirect method best represents bedload discharge in studied streams. No bedload-discharge rating curve was developed for the La Moine River, because the two measured bedload discharges are not sufficient for development of a rating curve and do not agree well with discharges computed by any of the three indirect methods. The dominant size of bedload particles in all streams sampled give results which cannot be used at this time. Collection-bag clogging may have been significant in the Green River, and large bed material gains or high flow velocities may have interfered with the operation of the sample in the Vermilion River. (USGS)

Water-Resources Investigations Report↗
USGS1982

Time of concentration and storage coefficient values for Illinois streams

Values of time of concentration and storage coefficient, two unit hydrograph parameters, are presented for 194 and 120 basins in Illinois. Tabulated values consist of those computed by previous investigators as well as those computed for 98 basins as part of this investigation. These additional values were computed by calibration of the U.S. Army Corps of Engineers Flood Hydrograph Package (HEC-1). The significance of differences in method used by each investigator to compute these unit hydrography parameters was evaluated by statistical comparison of four sets of time of concentration values and three sets of storage coefficient values. Because no difference due to method was identified, it is concluded that all of the values tabulated in this report can be used in any application for which time of concentration and storage coefficient are required.

Illinois↗
USGS1982

A technique for estimating time of concentration and storage coefficient values for Illinois streams

Values of the unit hydrograph parameters time of concentration ( TC ) and storage coefficient ( R ) can be estimated for streams in Illinois by a two-step technique developed from data for 98 gaged basins in the State. The sum of TC and R is related to stream length ( L ) and main channel slope ( S ) by the relation ( TC + R ) e = 35.2 L 0.39 S -0.78 . The variable R /( TC + R ) is not significantly correlated with drainage area, slope, or length, but does exhibit a regional trend. Regional values of R /( TC + R ) are used with the computed values of ( TC + R ) e to solve for estimated values of time of concentration ( TC e ) and storage coefficient ( R e ). The use of the variable R /( TC + R ) is thought to account for variations in unit hydrograph parameters caused by physiographic variables such as basin topography, flood-plain development, and basin storage characteristics.

Illinois↗