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G.M. Tillis

Publications and source records attributed to G.M. Tillis.

3 recordsLinked to original sources
USGS2001

Measuring Taylor Slough boundary and internal flows, Everglades National Park, Florida

Four intensive data-collection efforts, intended to represent the spectrum of precipitation events and associated flow conditions, were conducted during 1997 and 1998 in the Taylor Slough Basin, Everglades National Park. Flow velocities were measured by newly developed, portable Acoustic Doppler Velocity meters along three transects bisecting the Taylor Slough Basin from east to west, roughly perpendicular to the centerline axis of the slough as well as a fourth transect along the slough's axis. These meters provided the required levels of accuracy in flow-velocity measurements while enabling the rapid collection of multiple time series of flow data at remote sites. Concurrently, flow measurements were made along bordering road culverts and under L-31W and Taylor Slough bridges. Flows across the study area's boundaries provided net flow of water into the system and transect measurements provided flow data within the basin. Collected data are available through the World Wide Web (http://sofia.usgs.gov/projects/flow_velocity/). The high-water and low-water events corresponded with the highest and lowest flow velocities, respectively. The July 1998 data had lower than expected flow velocities and, in some cases, strong winds reversed flow direction.

Open-File Report↗
USGS1998

Determining discharge-coefficient ratings for selected coastal control structures in Broward and Palm Beach counties, Florida

Discharges through 10 selected coastal control structures in Broward and Palm Beach Counties, Florida, are presently computed using the theoretical discharge-coefficient ratings developed from scale modeling, theoretical discharge coefficients, and some field calibrations whose accuracies for specific sites are unknown. To achieve more accurate discharge-coefficient ratings for the coastal control structures, field discharge measurements were taken with an Acoustic Doppler Current Profiler at the coastal control structures under a variety of flow conditions. These measurements were used to determine computed discharge-coefficient ratings for the coastal control structures under different flow regimes: submerged orifice flow, submerged weir flow, free orifice flow, and free weir flow. Theoretical and computed discharge-coefficient ratings for submerged orifice and weir flows were determined at seven coastal control structures, and discharge ratings for free orifice and weir flows were determined at three coastal control structures. The difference between the theoretical and computed discharge-coefficient ratings varied from structure to structure. The theoretical and computed dischargecoefficient ratings for submerged orifice flow were within 10 percent at four of seven coastal control structures; however, differences greater than 20 percent were found at two of the seven structures. The theoretical and computed discharge-coefficient ratings for submerged weir flow were within 10 percent at three of seven coastal control structures; however, differences greater than 20 percent were found at four of the seven coastal control structures. The difference between theoretical and computed discharge-coefficient ratings for free orifice and free weir flows ranged from 5 to 32 percent. Some differences between the theoretical and computed discharge-coefficient ratings could be better defined with more data collected over a greater distribution of measuring conditions.

Water-Resources Investigations Report↗