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Victor A. Levesque

Publications and source records attributed to Victor A. Levesque.

5 recordsLinked to original sources
USGS2013

Tidal flow dynamics and background fluorescence of the Atlantic Intracoastal Waterway in the vicinity of Sullivan’s Island and the Isle of Palms, South Carolina, 2011-12

To effectively plan site-specific studies to understand the connection between wastewater effluent and shellfish beds, data are needed concerning flow dynamics and background fluorescence in the Atlantic Intracoastal Waterway near the effluent outfalls on Sullivan’s Island and the Isle of Palms. Tidal flows were computed by the U.S. Geological Survey for three stations and longitudinal water-quality profiles were collected at high and low tide. Flows for the three U.S. Geological Survey stations, the Atlantic Intracoastal Waterway by the Isle of Palms Marina, the Atlantic Intracoastal Waterway by the Ben M. Sawyer Memorial Bridge at Sullivan’s Island, and Breach Inlet, were computed for the 53-day period from December 4, 2011, to January 26, 2012. The largest flows occurred at Breach Inlet and ranged from -58,600 cubic feet per second (ft 3 /s) toward the Atlantic Intracoastal Waterway to 63,300 ft 3 /s toward the Atlantic Ocean. Of the two stations on the Atlantic Intracoastal Waterway, the Sullivan’s Island station had the larger flows and ranged from -6,360 ft 3 /s to the southwest (toward Charleston Harbor) to 8,930 ft 3 /s to the northeast. Computed tidal flow at the Isle of Palms station ranged from -3,460 ft 3 /s toward the southwest to 6,410 ft 3 /s toward the northeast. The synoptic water-quality study showed that the stations were well mixed vertically and horizontally. All fluorescence measurements (recorded as rhodamine concentration) were below the accuracy of the sensor and the background fluorescence would not likely interfere with a dye-tracer study.

South Carolina↗
USGS2012

Computing discharge using the index velocity method

Application of the index velocity method for computing continuous records of discharge has become increasingly common, especially since the introduction of low-cost acoustic Doppler velocity meters (ADVMs) in 1997. Presently (2011), the index velocity method is being used to compute discharge records for approximately 470 gaging stations operated and maintained by the U.S. Geological Survey. The purpose of this report is to document and describe techniques for computing discharge records using the index velocity method. Computing discharge using the index velocity method differs from the traditional stage-discharge method by separating velocity and area into two ratings—the index velocity rating and the stage-area rating. The outputs from each of these ratings, mean channel velocity (V) and cross-sectional area (A), are then multiplied together to compute a discharge. For the index velocity method, V is a function of such parameters as streamwise velocity, stage, cross-stream velocity, and velocity head, and A is a function of stage and cross-section shape. The index velocity method can be used at locations where stage-discharge methods are used, but it is especially appropriate when more than one specific discharge can be measured for a specific stage. After the ADVM is selected, installed, and configured, the stage-area rating and the index velocity rating must be developed. A standard cross section is identified and surveyed in order to develop the stage-area rating. The standard cross section should be surveyed every year for the first 3 years of operation and thereafter at a lesser frequency, depending on the susceptibility of the cross section to change. Periodic measurements of discharge are used to calibrate and validate the index rating for the range of conditions experienced at the gaging station. Data from discharge measurements, ADVMs, and stage sensors are compiled for index-rating analysis. Index ratings are developed by means of regression techniques in which the mean cross-sectional velocity for the standard section is related to the measured index velocity. Most ratings are simple-linear regressions, but more complex ratings may be necessary in some cases. Once the rating is established, validation measurements should be made periodically. Over time, validation measurements may provide additional definition to the rating or result in the creation of a new rating. The computation of discharge is the last step in the index velocity method, and in some ways it is the most straight-forward step. This step differs little from the steps used to compute discharge records for stage-discharge gaging stations. The ratings are entered into database software used for records computation, and continuous records of discharge are computed.

Techniques and Methods↗
USGS1996

Water flows and nutrient loads to the southwest coast of Florida—A study

Background The embayments and estuaries of Florida's southwest coast are an integral part of the south Florida ecosystem. Nutrients and other constituents are transported to these coastal waters by surface water and ground-water flow from the Everglades National Park (ENP) and the Big Cypress Preserve and by longshore and offshore tidal currents. The coastal area is an essential breeding ground for many estuarine and marine species and is a popular location for wilderness recreational pursuits as well as sport fishing. The volume of flow and the loads of nutrients being discharged from the streams draining the upland areas of ENP and Big Cypress Preserve currently are unknown. As part of Everglades restoration activities, the U.S. Army Corps of Engineers may change the volume or location of water deliveries to the ENP. Such changes could affect the volume or distribution of inflow and associated constituents that are transported into the coastal waters of southwest Florida. Proposals to change water deliveries to the Everglades National Park and efforts to improve the environmental health of Florida Bay cannot be evaluated without some understanding of the hydrologic and water-quality characteristics of tidal rivers and coastal embayments in the region. The southwest coast of Florida is part of a wilderness area with unique hydraulic characteristics that has historically been described as the "River of Grass." Flat terrain and lack of controlled topographic information has made it difficult to define drainage divides. Low gradients, coupled with tidal effects, create complex conditions under which to measure riverine flow. It has been almost thirty years since any effort has been made to monitor flow characteristics continuously in the area. Significant technological advancements have occurred during this time and this new technology can be applied to help obtain the information needed to make informed decisions about the future of this unique coastal area.

Florida↗
USGS1991

Wind generated wave resuspension of sediment in Old Tampa Bay, Florida

Vertical profiles of velocity and suspended-solids concentration were measured at a scientific instrumentation platform in Old Tampa Bay during the passage of a cold front in March 1990. Strong sustained winds behind the front increased wave activity in the bay, which resulted in resuspension of bottom sediments. The concentration of suspended solids, however, did not correlate with either wave height or mean velocity. A model of wave-current interaction was used to calculate the bottom shear stress, which proved to correlate well with suspended-solids concentration. This analysis shows the importance of considering wave-current interaction when studying sediment resuspension and near-bed transport processes in shallow estuaries.

Conference Paper↗