Geology topics

Clinton D. Hittle

Publications and source records attributed to Clinton D. Hittle.

3 recordsLinked to original sources

USGS2008

Bathymetric Surveys of Lake Arthur and Raccoon Lake, Pennsylvania, June 2007

In spring of 2007, bathymetric surveys of two Pennsylvania State Park lakes were performed to collect accurate data sets of lake-bed elevations and to develop methods and techniques to conduct similar surveys across the state. The lake-bed elevations and associated geographical position data can be merged with land-surface elevations acquired through Light Detection and Ranging (LIDAR) techniques. Lake Arthur in Butler County and Raccoon Lake in Beaver County were selected for this initial data-collection activity. In order to establish accurate water-surface elevations during the surveys, benchmarks referenced to NAVD 88 were established on land at each lake by use of differential global positioning system (DGPS) surveys. Bathymetric data were collected using a single beam, 210 kilohertz (kHz) echo sounder and were coupled with the DGPS position data utilizing a computer software package. Transects of depth data were acquired at predetermined intervals on each lake, and the shoreline was delineated using a laser range finder and compass module. Final X, Y, Z coordinates of the geographic positions and lake-bed elevations were referenced to NAD 83 and NAVD 88 and are available to create bathymetric maps of the lakes.

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USGS2006

Variability in supply and cross-shelf transport of pink shrimp ( Farfantepenaeus duorarum ) postlarvae into western Florida Bay

The variability in the supply of pink shrimp ( Farfantepenaeus duorarum ) postlarvae and the transport mechanisms of planktonic stages were investigated with field data and simulations of transport. Postlarvae entering the nursery grounds of Florida Bay were collected for three consecutive years at channels that connect the Bay with the Gulf of Mexico, and in channels of the Middle Florida Keys that connect the southeastern margin of the Bay with the Atlantic Ocean. The influx of postlarvae in the Middle Florida Keys was low in magnitude and varied seasonally and among years. In contrast, the greater postlarval influx occurred at the northwestern border of the Bay, where there was a strong seasonal pattern with peaks in influx from July through September each year. Planktonic stages need to travel up to 150 km eastward between spawning grounds (northeast of Dry Tortugas) and nursery grounds (western Florida Bay) in about 30 days, the estimated time of planktonic development for this species. A Lagrangian trajectory model was developed to estimate the drift of planktonic stages across the SW Florida shelf. The model simulated the maximal distance traveled by planktonic stages under various assumptions of behavior. Simulation results indicated that larvae traveling with the instantaneous current and exhibiting a diel behavior travel up to 65 km and 75% of the larvae travel only 30 km. However, the eastward distance traveled increased substantially when a larval response to tides was added to the behavioral variable (distance increased to 200 km and 85% of larvae traveled 150 km). The question is, when during larval development, and where on the shallow SW Florida shelf, does the tidal response become incorporated into the behavior of pink shrimp.

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USGS2004

Northeastern Florida Bay estuarine creek data, water years 1996-2000

From October 1995 to September 2000 (water years 1996-2000), continuous 15-minute stage, water velocity, salinity, and water temperature data were collected at seven estuarine creeks that flow into northeastern Florida Bay. These creeks include West Highway Creek, Stillwater Creek, Trout Creek, Mud Creek, Taylor River, Upstream Taylor River, and McCormick Creek. Discharge was computed at 15-minute intervals using mean water velocity and the cross-sectional area of the channel. Fifteen-minute unit values are presented for comparison of the quantity, quality, timing, and distribution of flows through the creeks. Revised discharge estimation formulas are presented for three noninstrumented sites (East Highway Creek, Oregon Creek and Stillwater Creek) that utilize an improved West Highway discharge rating. Stillwater Creek and Upstream Taylor River were originally noninstrumented sites; both were fully instrumented in 1999. Discharge rating equations are presented for these sites and were developed using a simple linear regression.

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