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E. F. Hubbard

Publications and source records attributed to E. F. Hubbard.

7 recordsLinked to original sources
USGS1982

Measurement of time of travel and dispersion in streams by dye tracing

The use of fluorescent dyes and tracing techniques provides a means for measuring the time-of-travel and dispersion characteristics of steady and gradually varied flow in streams. Measurements of the dispersion and concentration of dyes give insight into the behavior of soluble contaminants that may be introduced into a stream. This manual describes methods of measuring time of travel of water and waterborne solutes by dye tracing. The fluorescent dyes, measuring equipment used, and the field and laboratory procedures are also described. Methods of analysis and presentation to illustrate time-oftravel and dispersion characteristics of streams are provided.

Techniques of Water-Resources Investigations↗
USGS1975

Evaluation of reservoir sites in North Carolina: Regional relations for estimating the reservoir capacity needed for a dependable water supply

Draft-storage-frequency relations, which show the storage required for a reservoir to furnish a specified withdrawal or draft are regionalized for four zones in the State, using the mean annual flow of the streams as an index. The differences between the zones primarily reflect differences in the variability of stream flow. To assure the available draft will fall below 75 percent of the mean annual flow of a stream only once in 50 years on the average, a reservoir in the mountains would need a usable storage capacity of 45 percent of the mean annual runoff of the impounded stream. In comparison, reservoirs in parts of the Piedmont furnishing a draft of 75 percent of the mean annual flow must have usable storage equal to 60 percent of the mean annual runoff of the stream. In the inner Coastal Plain the storage required increases to 84 per-cent, and in the outer Coastal Plain to about 110 percent. These increases in storage necessary to furnish a certain draft are indicative of the general increase in streamflow variability, both seasonally and between years, that occurs from west to east in the State. Net evaporative draft, the evaporative loss from reservoirs when annual evaporation exceeds annual precipitation, also varies from west to east. For instance, a reservoir impounding a Piedmont stream, and designed with a 5 percent chance of deficiency, will have a net evaporative draft about twice as large as a similar sized reservoir in the Coastal Plain. In the mountains, annual precipitation always exceeds evaporation because of the cooler temperatures and higher rates of precipitation. Annual net evaporation is also proportionately smaller for large reser voirs than for small ones. On a Coastal Plain reservoir, with storage equivalent to the mean annual runoff of the stream and being drafted at 90 percent of the mean annual flow, the net evaporation for a stream with a mean annual runoff of only 500 acre-feet (0.62 cubic hectometres) is three times as great as for a stream with mean annual runoff of 100,000 acre-feet (123 cubic hectometres). Thus, one large reservoir has less evaporation loss than several small ones capable of furnishing, collectively, the same reliable draft. Under some circumstances, sedimentation can quickly reduce the available storage in a reservoir, thus decreasing the reliable draft. Estimated sedi-mentation rates in the Piedmont can range from 240 acre-feet per year (0.3 cubic hectometres per year) in a severely exposed drainage basin of 10 square miles (26 square kilometres) to 0.4 acre-feet per year (493 cubic metres per year) in a wooded basin of the same size. Seepage beneath and around a reservoir dam is normally not significant in the State. The usual engineering practices should be followed, however, to avoid locating the dam on an open or active fault, cavernous limestone, or continuous beds of sand or gravel.

North Carolina↗
USGS1972

Movement and dispersion of soluble pollutants in the Northeast Cape Fear Estuary, North Carolina

This report presents the results of a fluorescent-dye-tracing study to determine the concentrations of a pollutant that would be present in the Northeast Cape Fear Estuary at various rates of continuous waste injection and freshwater inflow. Rhodamine WT dye was introduced into the estuary at a constant rate over a 24.8-hour period (two tidal cycles) at a point 6.4 miles upstream from the mouth in Wilmington, N.C., and concentrations were monitored at several selected sections in the tide-affected part of the river for 17 days. The range between high and low tide in this reach of the estuary averages at-rut 3.5 feet, and there is usually strong flow in both directions. Results of the dye study indicate that if a pollutant were injected at a rate of 100 pounds per day under the conditions of relatively low inflow existing' at the time, concentrations would ultimately build up to 20 micrograms of dye per liter of water 1,000 feet downstream. The flushing time during the study is estimated to be 17 days. These results are extrapolated to include periods of lower or higher inflow. For example, at average intervals of 10 years, it is estimated that inflow is so low that 100 days are required for a pollutant to travel the 6.4 miles from the point of waste release to the mouth of the river. Under these conditions it is expected that 1,000 feet downstream from the point of waste discharge, daily maximum concentrations will average about 130 micrograms per liter for each 100 pounds of pollutant injected per day. Results of a continuous discharge measurement of flow made by current meter during a complete tidal cycle are presented as a part of this report. Data from this measurement and other evidence indicate that net upstream flow in the estuary is possible over a period of several days.

North Carolina↗