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R.R. Mason

Publications and source records attributed to R.R. Mason.

9 recordsLinked to original sources
USGS2013

A generalized Grubbs-Beck test statistic for detecting multiple potentially influential low outliers in flood series

he Grubbs-Beck test is recommended by the federal guidelines for detection of low outliers in flood flow frequency computation in the United States. This paper presents a generalization of the Grubbs-Beck test for normal data (similar to the Rosner (1983) test; see also Spencer and McCuen (1996)) that can provide a consistent standard for identifying multiple potentially influential low flows. In cases where low outliers have been identified, they can be represented as “less-than” values, and a frequency distribution can be developed using censored-data statistical techniques, such as the Expected Moments Algorithm. This approach can improve the fit of the right-hand tail of a frequency distribution and provide protection from lack-of-fit due to unimportant but potentially influential low flows (PILFs) in a flood series, thus making the flood frequency analysis procedure more robust.

Water Resources Research↗
USGS2012

Quantifying uncertainty in discharge measurements: A new approach

The accuracy of discharge measurements using velocity meters and the velocity-area method is typically assessed based on empirical studies that may not correspond to conditions encountered in practice. In this paper, a statistical approach for assessing uncertainty based on interpolated variance estimation (IVE) is introduced. The IVE method quantifies all sources of random uncertainty in the measured data. This paper presents results employing data from sites where substantial over-sampling allowed for the comparison of IVE-estimated uncertainty and observed variability among repeated measurements. These results suggest that the IVE approach can provide approximate estimates of measurement uncertainty. The use of IVE to estimate the uncertainty of a discharge measurement would provide the hydrographer an immediate determination of uncertainty and help determine whether there is a need for additional sampling in problematic river cross sections. ?? 2009 ASCE.

Conference Paper↗
USGS1996

Estimating flood hydrographs for urban basins in North Carolina

A dimensionless hydrograph for North Carolina was developed from data collected in 29 urban and urbanizing basins in the State. The dimen- sionless hydrograph can be used with an estimate of peak flow and basin lagtime to synthesize a design flood hydrograph for urban basins in North Carolina. Peak flows can be estimated from a number of avail- able techniques; a procedure for estimating basin lagtime from main channel length, stream slope, and percentage of impervious area was developed from data collected at 50 sites and is presented in this report. The North Carolina dimensionless hydrograph provides satis- factory predictions of flood hydrographs in all regions of the State except for basins in or near Asheville where the method overestimated 11 of 12 measured hydrographs. A previously developed dimensionless hydrograph for urban basins in the Piedmont and upper Coastal Plain of South Carolina provides better flood-hydrograph predictions for the Asheville basins and has a standard error of 21 percent as compared to 41 percent for the North Carolina dimensionless hydrograph.

North Carolina↗
USGS1992

The storm and flood of September 15, 1989, in Fayetteville, North Carolina

The storm of September 15, 1989, in and around the city of Fayetteville, North Carolina, produced the most extensive flooding of Fayetteville since 1945. The flood inundated 925 acres in the city along Cross Creek and Blounts Creek and their tributaries, flooded 338 buildings, caused damages in excess of $10 million and claimed the lives of 2 small children. Twenty-two roads and five dams were overtopped, and three earthen dams failed. Recorded rainfall and streamflow data indicate that the storm and flood were relatively rare events. Recorded rainfall totals for durations of less than 2 hours were not exceptionally rare or unusual, but rainfall totals for 2-, 3-, and 6-hr durations recorded at a National Weather Service rain gage substantially exceeded 100-yr rainfall amounts by approximately 31, 28, and 12%, respectively. Recorded unit-peak discharges ranged from 33 to 6,060 cu ft/sec/sq mi (the latter downstream from a dam failure). Peak discharges at 6 of 10 stream-gaging sites had recurrence intervals greater than 100 yrs. Flooding of Cross Creek and Blounts Creek upstream of Robeson Street was generally less extensive than the 100-yr flood, as delineated by the Federal Emergency Management Agency. Downstream of Robeson Street, the flooding was more extensive.

North Carolina↗
USGS1990

Effects of channel modifications on the hydrology of Chicod Creek basin, North Carolina, 1975-87

Drainage modifications in this Coastal Plain basin from 1978 to 1981 consisted of channel excavation and clearing of blockages. A study was begun in 1975 to define hydrologic conditions of the basin before, during, and after modifications and to determine what changes were attributed to modifications. Surface-water conditions were altered during and following modifications. Minimum flow at Juniper Branch was increased from less than 0.1 cu ft/sec to 0.4 cu ft/second;streamflow variability was reduced from an index of 0.87 to 0.49. In-channel velocity at Chicod Creek was increased from a mean of 0.4 ft/sec to 1.5 ft/sec. Substantial groundwater level declines were observed in wells 180 and 250 ft from Juniper Branch during the modifications phase;these were 0.4 and 0.2 ft, respectively. However, most surface-water and groundwater conditions returned nearly to premodification levels by 1987. Water-quality characteristics monitored during the investigation included physical, chemical, and bacteriological characteristics. Physical characteristics monitored were suspended sediment, temperature, dissolved oxygen, and pH. Of these physical characteristics, only sediment concentrations increased substantially during channel modifications. Chemical characteristics studied were major dissolved constituents, nutrients, trace metals, and pesticides. Substantial changes ranged from a decline in total iron concentrations of 77% to an increase in total nitrite concentrations of 130%. Changes in many chemical characteristics persisted following channel modifications. Bacterial counts did not change substantially.

North Carolina↗
USGS1988

Programs for generating data tables for the annual water-resources data report of the U.S. Geological Survey

The U.S. Geological Survey has developed software that interfaces with the Automated Data Processing System to facilitate and expedite preparation of the annual water-resources data report. This software incorporates a feature that prepares daily values tables and appends them to previously edited files containing station manuscripts. Other features collate the merged files with miscellaneous sections of the report. The report is then printed as page-size, camera-ready copy. All system components reside on a minicomputer; this provides easy access and use by remote field offices. Automation of the annual report preparation process results in significant savings of labor and cost. Use of the system for producing the 1986 annual report in the North Carolina District realized a labor savings of over two man-months. A fully implemented system would produce a greater savings and speed release of the report to users.

Open-File Report↗
USGS1987

Magnitude and frequency of floods in rural and urban basins of North Carolina

The applicability of the nationwide urban flood relations in the Piedmont and Coastal Plain provinces is evaluated. Data for 254 gaging stations on rural streams with 10 or more years of record were used in multiple linear regression analyses with basin and climatic variables, to derive regional relations for estimating flood discharges having recurrence intervals of 2- to 100-years. Rural relations are presented for three hydrologic areas: (1) Blue Ridge-Piedmont, (2) Coastal Plain, and (3) Sand Hills. Drainage area is the only basin characteristic in the relations. The average standard error of estimate of the relations for the Blue Ridge-Piedmont, Coastal Plain, and Sand Hills hydrologic areas is 44, 39, and 24%, respectively. Flood discharges for the 2-, 5-, 10-, 25-, 50-, and 100-year recurrence intervals for the 254 streamflow stations used in the regionalization study are also presented. Flood frequency distributions of simulated annual maximum discharges for four urban basins in the Coastal Plain indicate that the nationwide relations are applicable in the province. The root mean squared error for the 10- and 100-year flood discharges, using the nationwide relations, is 44% and 49%, respectively. Simulated data for six sites in the Piedmont were used to analyze the applicability of the nationwide urban relations in the province. The root mean squared error is 64% for the 10-year flood and 42% for the 100-year flood. No recommendation is made concerning use of the nationwide relations in the Piedmont.

North Carolina↗
USGS1985

Cost-effectiveness of the stream-gaging program in North Carolina

This report documents the results of a study of the cost-effectiveness of the stream-gaging program in North Carolina. Data uses and funding sources are identified for the 146 gaging stations currently operated in North Carolina with a budget of $777,600 (1984). As a result of the study, eleven stations are nominated for discontinuance and five for conversion from recording to partial-record status. Large parts of North Carolina 's Coastal Plain are identified as having sparse streamflow data. This sparsity should be remedied as funds become available. Efforts should also be directed toward defining the efforts of drainage improvements on local hydrology and streamflow characteristics. The average standard error of streamflow records in North Carolina is 18.6 percent. This level of accuracy could be improved without increasing cost by increasing the frequency of field visits and streamflow measurements at stations with high standard errors and reducing the frequency at stations with low standard errors. A minimum budget of $762,000 is required to operate the 146-gage program. A budget less than this does not permit proper service and maintenance of the gages and recorders. At the minimum budget, and with the optimum allocation of field visits, the average standard error is 17.6 percent.

North Carolina↗