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Geology topics

Charles Parrett

Publications and source records attributed to Charles Parrett.

At least 37 records · Page 2Linked to original sources
USGS1997

Method for rapid estimation of scour at highway bridges based on limited site data

Limited site data were used to develop a method for rapid estimation of scour at highway bridges. The estimates can be obtained in a matter of hours rather than several days as required by more-detailed methods. Such a method is important because scour assessments are needed to identify scour-critical bridges throughout the United States. Using detailed scour-analysis methods and scour-prediction equations recommended by the Federal Highway Administration, the U.S. Geological Survey, in cooperation with the Montana Department of Transportation, obtained contraction, pier, and abutment scour-depth data for sites from 10 States.The data were used to develop relations between scour depth and hydraulic variables that can be rapidly measured in the field. Relations between scour depth and hydraulic variables, in the form of envelope curves, were based on simpler forms of detailed scour-prediction equations. To apply the rapid-estimation method, a 100-year recurrence interval peak discharge is determined, and bridge- length data are used in the field with graphs relating unit discharge to velocity and velocity to bridge backwater as a basis for estimating flow depths and other hydraulic variables that can then be applied using the envelope curves. The method was tested in the field. Results showed good agreement among individuals involved and with results from more-detailed methods. Although useful for identifying potentially scour-critical bridges, themethod does not replace more-detailed methods used for design purposes. Use of the rapid- estimation method should be limited to individuals having experience in bridge scour, hydraulics, and flood hydrology, and some training in use of the method.

Water-Resources Investigations Report↗
USGS1997

Regional analysis of annual precipitation maxima in Montana

Dimensionless precipitation-frequency curves for estimating precipitation depths having large recurrence intervals were developed for 2-, 6-, and 24-hour storm durations for three homogeneous regions in Montana. Within each homogeneous region, at-site annual precipitation maxima were made dimensionless by dividing by the at-site mean and grouped so that a single frequency curve would be applicable for each duration. L-moment statistics were used to help define the homogeneous regions and to develop the dimensionless precipitation- frequency curves. Data from 459 precipitation stations were used after application of statistical tests to ensure that the data were not serially correlated and were stationary over the general period of data collection (1900-92). The data were found to have a small, but significant, degree of interstation correlation. The GEV distribution was used to construct dimensionless frequency curves of annual precipitation maxima for each duration within each region. Each dimensionless frequency curve was considered to be reliable for recurrence intervals up to the effective record length. Because of significant, though small, interstation correlation in all regions for all durations, and because the selected regions exhibited some heterogeneity, the effective record length was considered to be less than the total number of station-years of data. The effective record length for each duration in each region was estimated using a graphical method and found to range from 500 years for 6-hour duration data in Region 2 to 5,100 years for 24-hour duration data in Region 3.

Water-Resources Investigations Report↗
USGS1996

Synthesis of natural flows at selected sites in the upper Missouri River basin, Montana, 1928-89

Natural monthly streamflows were synthesized for the years 1928-89 for 43 sites in the upper Missouri River Basin upstream from Fort Peck Lake in Montana. The sites are represented as nodes in a streamflow accounting model being developed by the Bureau of Reclamation. Recorded and historical flows at most sites have been affected by human activities including reservoir storage, diversions for irrigation, and municipal use. Natural flows at the sites were synthesized by eliminating the effects of these activities. Recorded data at some sites do not include the entire study period. The missing flows at these sites were estimated using a statistical procedure. The methods of synthesis varied, depending on upstream activities and information available. Recorded flows were transferred to nodes that did not have streamflow-gaging stations from the nearest station with a sufficient length of record. The flows at one node were computed as the sum of flows from three upstream tributaries. Monthly changes in reservoir storage were computed from monthend contents. The changes in storage were corrected for the effects of evaporation and precipitation using pan-evaporation and precipitation data from climate stations. Irrigation depletions and consumptive use by the three largest municipalities were computed. Synthesized natural flow at most nodes was computed by adding algebraically the upstream depletions and changes in reservoir storage to recorded or historical flow at the nodes.

Water-Resources Investigations Report↗
USGS1996

Synthesis of monthly natural flows for selected sites in the Musselshell River basin, Montana, base period 1929-89

Synthesized monthly natural streamflows were required at 13 sites for use in a streamflow- accounting model to evaluate the effects of various water-allocation schemes on water availability in the Musselshell River Basin in central Montana. Records of monthly streamflow at 14 streamflow-gaging stations were used to synthesize monthly natural flows at tributaries and the 13 synthesis sites. A streamflow-record extension program was used to extend flow records at the 14 gaged sites to a common base period, 1929-89. To synthesize monthly natural flows at 10 sites on the Musselshell River mainstem, synthesized monthly natural flows at all signi- ficant tributary streams were required. Results from a previous study were used to synthesize tributary natural flows. Monthly natural flows at each mainstem site downstream from the first site were synthesized by successively adding monthly natural flows from intervening tributaries to the next upstream mainstem site. Special methods using extended-record flows from gaged tributaries were used to synthesize monthly natural flows at three tributary sites. Synthesized mean annual natural flows were found to be greater than mean annual extended-record flows at three selected comparison sites on the Musselshell River. The differences between mean natural and extended-record flows (depletions) at Harlowton and Musselshell were considered to be reasonable given the amount of irrigated acreage upstream from the two sites. The differences at Mosby, the site farthest downstream, was less than at Musselshell, the next upstream site, indicating that the methods of synthesis had error. The synthesis error generally was attributed to the larger natural variability of tributary flows in the lower portion of the Musselshell River Basin.

Water-Resources Investigations Report↗
USGS1996

Procedures for estimating unit hydrographs for large floods at ungaged sites in Montana

Flood hydrographs for 26 gaging stations and rainfall data were used together with a rainfall-runoff simulation model to derive unit hydrographs and important unit-hydrograph variables. Methods were developed for estimating unit hydrographs at ungaged sites using either the Clark or dimensionless unit-hydrograph methods. The 26 derived unit hydrographs were compared with those calculated by the two estimation methods. The two methods performed about equally well in matching derived unit-hydrograph peaks and shapes.

Montana↗
USGS1996

Regionalization of annual precipitation maxima in Montana

Precipitation depth estimation methods based on dimensionless precipitation-frequency curves were developed for 2-, 6-,and 24-hour storm durations for three homogeneous regions in Montana. Data from 402 daily and hourly precipitation stations and 54 daily precipitation stations were analyzed using the methods to form a database of the regions' annual precipitation maxima.

Conference Paper↗
USGS1995

Simulated monthly hydrologic data and estimated flood characteristics for Cherry Creek at a proposed reservoir site near Terry, Montana

Methods used to simulate a monthly hydrologic budget for water years 1937-92 for the proposed Cherry Creek Reservoir (maximum volume about 14,100 acre-feet) are described and monthly results of the simulation are presented. The budget is based on recorded and estimated streamflow, precipitation, evaporation, and estimated reservoir seepage. The budget also includes water diversions from the Yellowstone River whenever the reservoir depth was less than 20 feet (minimum operating level of 2,260 feet) and outflows whenever the reservoir elevation exceeded a maximum operating level of 2,290 feet. Monthly suspended sediment and dissolved-solids concentrations in the reservoir were estimated from regression relations between logarithms of concentration and streamflow for Cherry Creek and for the Yellowstone River near Sidney, Montana. The results of the reservoir simulation indicate that flows from Cherry Creek, an intermittent stream having a drainage area of about 360 square miles, generally were adequate to maintain the reservoir elevation above the minimum operating level if no seepage loss occurred. With a seepage loss of 3 cubic feet per second, flow diversions from the Yellowstone River were required for 34 percent of the months to maintain the reservoir elevation at minimum operating level. The reservoir elevation generally was maintained near maximum operating level for a seepage loss of 0 cubic feet per second, but generally was close to minimum operating level for a seepage loss of 3 cubic feet per second. Cumulative sediment deposition for the 56-year period was estimated to be about 138 acre-feet from Cherry Creek alone and only slightly more (149 acre-feet) when additional water was imported from the Yellowstone River. The simulated concentration of dissolved solids in the reservoir showed a slightly increasing trend over time, interrupted by several large decreases, for no reservoir seepage loss. The maximum concentration for no seepage loss reached a maximum value of about 2,500 milligrams per liter in 1982. For a seepage loss of 3 cubic feet per second, water was imported from the Yellowstone River, and the concentration generally ranged from about 500 to about 1,200 milligrams per liter throughout the period. Flood hydrographs and volumes for flood discharges having 25-, 50-, and 100-year recurrence intervals were estimated from synthetic 24-hour duration storms having total storm depths with recurrence intervals of 25, 50, and 100 years. These synthetic storms were used in a rainfall-runoff model (HEC-1) based on the Clark unit-hydrograph method to develop flood hydrographs from which volumes were computed. The peak discharges of the 25-, 50-, and 100-year flood hydrographs determined from the rainfallrunoff model compared closely to the 25-, 50-, and 100-year peak discharges determined from regional equations developed by the U. S. Geological Survey. The volume of the 100-year hydrograph developed from the HEC-1 model was about 11,250 acre-feet.

Montana↗
USGS1995

Synthesis of natural flows at selected sites in and near the Milk River basin, Montana, 1928-89

Natural monthly streamflows were synthesized for the years 1928-89 at 2 sites in the St. Mary River Basin and 11 sites in the Milk River Basin in north- central Montana. The sites are represented as nodes in a streamflow accounting model being developed by the Bureau of Reclamation for the Milk River Basin. Recorded flows at most sites have been affected by human activities, including reservoir storage and irrigation diversions. The flows at the model nodes were corrected for the effects of these activities to obtain synthesized flows. The synthesized flows at nodes with seasonal and short-term records were extended using a statistical technique. The methods of synthesis varied, depending on upstream activities and information available. Flows at sites in the St. Mary River Basin and at the Milk River at Eastern Crossing of International Boundary pre- viously had been synthesized. The flows at mainstem sites downstream from the Milk River at Eastern Crossing were synthesized by adding synthesized natural runoff from intervening drainage areas to natural flows for Milk River at Eastern Crossing. Natural runoff from intervening drainage areas was estimated by multiplying recorded flows at selected index gaging stations on tributary streams by the ratio of the intervening drainage area to the combined drainage area of the index stations. The recorded flows for Milk River at Western Crossing of International Boundary and for Peoples Creek near Dodson, Montana, were assumed to be natural flows. The synthesized annual flows at the mouth of the Milk River compared favorably with the recorded flows near the mouth when the effects of upstream irrigation were considered.

Water-Resources Investigations Report↗
USGS1994

Estimates of monthly streamflow characteristics and dominant-discharge hydrographs for selected sites in the lower Missouri and Little Missouri River basins in Montana

Various streamflow characteristics were estimated for water-reservation purposes for 17 sites in the lower Missouri River Basin and four sites in the Little Missouri River Basin in Montana. The characteristics were mean monthly and annual streamflow and monthly mean streamflow that is exceeded 90, 80, 50, and 20 percent of the time. In addition, dominant-discharge hydrographs were estimated for 10 of the 17 sites in the lower Missouri River Basin and for four sites in the Little Missouri River Basin. Dominant discharge was considered to be equal to the peak discharge having a recurrence interval of two years. Monthly streamflow characteristics generally were based on a common 1937-86 base period. A mixed-station record-extension program was used to estimate missing flow data for streamflow-gaging stations. Two methods were used to estimate characteristics at ungaged sites. One method was based on corre- lating discharge measurements at the estimating site with concurrent discharges at a nearby gaged site. The second method was based on using a drainage-area ratio to transfer characteristics at a gaged site to the estimating site. Dominant discharges for gaged sites were obtained from a previous flood-frequency report or by fitting a log-Pearson Type 3 probability distribution to recorded peak-flow data. A drainage-area-ratio adjustment was used to transfer dominant dis- charges from gaged sites to ungaged sites. Dominant-discharge hydrographs were determined from visual examination of recorded hydrographs having maximum daily discharges that were relatively close to the estimated dominant discharges.

Water-Resources Investigations Report↗
USGS1994

Relation between largest known flood discharge and elevation in Montana

Previous studies relating unit discharge to elevation indicated that large floods in the Rocky Mountains may be limited by elevation. However, high-elevation data are sparse in Montana and the indications may not be entirely correct. Based on data at 19 sites in Montana, a strong log-linear relation exists between large-flood discharge and drainage area. The use of unit discharge (peak discharge divided by drainage area) to compare flood magnitude from site to site may thus be biased and tend to overstate flood magnitude for small basins. Removal of the bias by use of a revised unit discharge (peak discharge divided by drainage area raised to the 0.16 power) results in no apparent relation between revised unit discharge and elevation in two areas of Montana. However, because of a paucity of data, the magnitude of revised unit discharge at elevations greater than 1,650 m is largely unknown. Additional data and research are needed to resolve questions about mountain flood hydrology.

Conference Paper↗
USGS1993

Flood discharges in the upper Mississippi River basin, 1993

From mid-June through early August 1993, flooding was severe in the upper Mississippi River Basin following a wet-weather pattern that persisted over the area for at least 6 months before the flood. The magnitude and timing of several intense rainstorms in late June and July, combined with wet antecedent climatic conditions, were the principal causes of the flooding. Flood-peak discharges that equaled or exceeded the 10-year recurrence interval were recorded at 154 streamflow-gaging stations in the upper Mississippi River Basin. At 41 streamflowgaging stations, the peak discharge was greater than the previous maximumknown discharge. At 15 additional gaging stations, peak discharges exceeded the previous maximum regulated peak discharge. At 45 gaging stations, peak discharges exceeded 100-year recurrence intervals.

upper Mississippi River basin↗
USGS1993

Estimation of unit hydrographs for large floods at ungaged sites in Montana

Methods were developed for estimating unit hydro- graphs at ungaged sites in Montana using either the Clark or dimensionless unit-hydrograph method. Flood hydrograph data for 26 U.S. Geological Survey streamflow-gaging stations and rainfall data were used together with a rainfall-runoff simulation model (HEC-1) to derive unit hydrographs and important unit-hydrograph variables. A multiple- regression analysis relating four unit-hydrograph variables (time of concentration, basin-storage coefficient, Snyder standard lag, and dimensionless peak discharge) to basin characteristics showed a significant (95 percent confidence level) relation only with drainage area for time of concentration, basin-storage coefficient, and Snyder standard lag. In the regression relation for dimensionless peak discharge, the only significant basin characteristic was basin factor, a function of channel length, distance from the basin centroid to mouth, and channel slope. An alternative equation based only on drainage area was almost as reliable. Regression equations for estimating basin-storage coefficient and dimensionless peak discharge had coefficients of determination (r sq) ranging from 0.19 to 0.47. An average dimensionless unit hydrograph was determined for the 26 sites, and a method was developed for adjusting its magnitude and shape to account for site-specific information. The 26 derived unit hydrographs were compared with those calculated by the described estimation methods. The two methods performed about equally well in matching derived unit-hydrograph peaks and shapes. (USGS)

Montana↗
USGS1993

Bridge scour and change in contracted section, Razor Creek

Two large floods, 3 and 4 times the estimated 100-year peak discharge, occurred in 1986 and 1991 at a timber-pile bridge over Razor Creek in Montana. A bridge section surveyed after the 1991 flood was compared with a 1955 design section and showed total scour of 0.85 m at the left abutment, 2.23 m at the right abutment, and 0. 94 m at the pile bents. Calculated total scour based on equations recommended by the Federal Highway Administration and data obtained after the 1991 flood was 3.20 m at the left abutment, 4.36 m at the right abutment, and 2.13 m at the pile bents. Residual scour from floods prior to 1986 was presumed to be negligible because no floods of significant magnitude were documented. Also, scour for the 1986 flood is believed to be significantly less than for the 1991 flood because the 1986 peak discharge was significantly smaller and the contracted section for the 1986 peak discharge was 22 m upstream from the bridge.

Conference Paper↗
USGS1990

Streamflow characteristics of small tributaries of Rock Creek, Milk River basin, Montana, base period water years 1983-87

Five streamflow-gaging stations were installed in the Rock Creek basin north of the Milk River near Hinsdale, Montana. Streamflow was monitored at these stations and at an existing gaging station upstream on Rock Creek from May 1983 through September 1987. The data collected were used to describe the flow characteristics of four small tributary streams. Annual mean streamflow ranges from 2.8 to 57 cu ft/sec in the mainstem and from 0 to 0.60 cu ft/sec in the tributaries. Monthly mean streamflow ranged from 0 to 528 cu ft/sec in Rock Creek and from zero to 5.3 cu ft/sec in the four tributaries. The six gaged sites show similar patterns of daily mean streamflow during periods of large runoff, but substantial individual variations during periods of lesser runoff. During periods of lesser runoff , the small tributaries may have small daily mean streamflows. At other times, daily mean streamflow at the two mainstem sites decreased downstream. Daily mean streamflow in the tributaries appears to be closely related to daily mean streamflow in the mainstem only during periods of substantial area-wide runoff. Thus, streamflow in the tributaries resulting from local storms or local snowmelt may not contribute to streamflow in the mainstem. (USGS)

Water-Resources Investigations Report↗