Geology topics

B.F. Pope

Publications and source records attributed to B.F. Pope.

4 recordsLinked to original sources

USGS2007

Identification of changes in streamflow characteristics

A set of procedures for identifying changes in selected streamflow characteristics at sites having long-term continuous streamflow records is illustrated by using streamflow data from the Waccamaw River at Freeland, North Carolina for the 55-year period of 1940-1994. Data were evaluated and compared to streamflows in the adjacent Lumber River Basin to determine if changes in streamflow characteristics in the Waccamaw River were localized and possibly the result of some human activity, or consistent with regional variations. Following 1963, droughts in the Waccamaw Basin seem to have been less severe than in the Lumber Basin, and the annual one-, seven-, and 30-day low flows exhibited a slightly increasing trend in the Waccamaw River. Mean daily flows in the Waccamaw River at the 90 percent exceedance level (low flows) during 1985-194, a relatively dry period, were very nearly equal to flows at the same exceedance level for 1970-1979, which represents the 10-year period between 1940 and 1994 with the highest flows. Prior to the 1980s, flows per unit drainage area in the Waccamaw Basin were generally less than those in the Lumber Basin, but after 1980, the opposite was true. The ratio of base flow to runoff in the Waccamaw River may have changed relative to that in the Lumber River in the late 1970s. There was greater variability in Waccamaw River streamflow than in Lumber River flow, and flow variability in the Waccamaw River may have increased slightly during 1985-1994.

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USGS1996

Estimation of flood-frequency characteristics of small urban streams in North Carolina

A statewide study was conducted to develop methods for estimating the magnitude and frequency of floods of small urban streams in North Carolina. This type of information is critical in the design of bridges, culverts and water-control structures, establishment of flood-insurance rates and flood-plain regulation, and for other uses by urban planners and engineers. Concurrent records of rainfall and runoff data collected in small urban basins were used to calibrate rainfall-runoff models. Historic rain- fall records were used with the calibrated models to synthesize a long- term record of annual peak discharges. The synthesized record of annual peak discharges were used in a statistical analysis to determine flood- frequency distributions. These frequency distributions were used with distributions from previous investigations to develop a database for 32 small urban basins in the Blue Ridge-Piedmont, Sand Hills, and Coastal Plain hydrologic areas. The study basins ranged in size from 0.04 to 41.0 square miles. Data describing the size and shape of the basin, level of urban development, and climate and rural flood charac- teristics also were included in the database. Estimation equations were developed by relating flood-frequency char- acteristics to basin characteristics in a generalized least-squares regression analysis. The most significant basin characteristics are drainage area, impervious area, and rural flood discharge. The model error and prediction errors for the estimating equations were less than those for the national flood-frequency equations previously reported. Resulting equations, which have prediction errors generally less than 40 percent, can be used to estimate flood-peak discharges for 2-, 5-, 10-, 25-, 50-, and 100-year recurrence intervals for small urban basins across the State assuming negligible, sustainable, in- channel detention or basin storage.

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USGS1996

Streamflow characteristics of the Waccamaw River at Freeland, North Carolina, 1940-94

Streamflow characteristics of the Waccamaw River at Freeland, North Carolina, for the period 1940-94 were described and compared to stream- flows in the adjacent Lumber River Basin. Precipitation in the two basins was about equal for the study period. During 1940-63, stream- flows in the Waccamaw and Lumber Rivers were essentially identical relative to average conditions. The flow regime from the late 1950's to the early 1980's was distinctly wetter than the flow regimes which immediately preceded and followed this period. Following 1963, droughts in the Waccamaw Basin seem to have been less severe than in the Lumber Basin, and the annual 1-, 7-, and 30-day low flows exhibited a slightly increasing trend in the Waccamaw River. Mean daily flow in the Wacca- maw River at the 90-percent exceedance level (low flows) during 1985- 94, a relatively dry period, was very nearly equal to flows at the same exceedance level for 1970-79, the wettest 10-year period between 1940 and 1994. Prior to the 1980's, flows per unit drainage area in the Waccamaw Basin were generally less than those in the Lumber Basin, but after 1980, the opposite was true. There is an increasing trend in the difference between Waccamaw River and Lumber River high flows, primarily as a result of increases in Waccamaw River high flows. On average, streamflow in the Waccamaw River consisted of 53.3 percent base flow, but base flow accounted for 70.6 percent of the total flow in the Lumber River, which is more typical of Coastal Plain streams. The ratio of base flow to runoff in the Waccamaw River may have changed relative to that in the Lumber River in the late 1970's. There was greater variability in Waccamaw River streamflow than in Lumber River flow, and flow variability in the Waccamaw River may have increased slightly during 1985-94.

North Carolina↗

USGS1996

Simulated peak flows and water-surface profiles for Scott Creek near Sylva, North Carolina

Peak flows were simulated for Scott Creek, just upstream from Sylva, in Jackson County, North Carolina, in order to provide Jackson County officials with information that can be used to improve preparation for and response to flash floods along the reach of Scott Creek that flows through Sylva. A U.S. Geological Survey rainfall-runoff model was calibrated using observed rainfall and streamflow data collected from March 1994 through September 1995. Standard errors for calibration were 34 percent for runoff volumes and 21 percent for peak flows. The calibrated model was used to simulate peak flows resulting from syn- thetic rainfall amounts of 1.0, 2.5, 5.0, and 7.5 inches in 24-hour periods. For each rainfall amount, peak flows were simulated under low-, moderate-, and high-antecedent soil-moisture conditions, represented by selected 3-month periods of daily rainfall and evaporation record from nearby climatic-data measuring stations. Simulated peak flows ranged from 89 to 10,100 cubic feet per second. Profiles of water-surface elevations for selected observed and simu- lated peak flows were computed for the reach of Scott Creek that flows through Sylva, North Carolina. The profiles were computed using the U.S. Army Corps of Engineers HEC-2 Water Surface Profiles computer program and channel cross-section data collected by the Tennessee Valley Authority. The stage-discharge relation for Scott Creek at the simulation site has changed since the collection of the cross-section data. These changes, however, are such that the water-surface profiles presented in this report likely overestimate the true water-surface elevations at the simulation site for a given peak flow

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