Investigation Of Pressure Fluctuations In The Hyporheic Zone In Response To Flow Around A Hydraulic Structure

Erosion around a cylinders is a well studied field. Particles erode when lift and drag forces overcome a critical threshold. These forces are typically studied from above the water-riverbed interface. This study maps hyporheic pressure fluctuations as they are related to surface water velocity. The pressure map is used to evaluate lift enhancement and destabilization forces on the riverbed. High pressure events in the subsurface help generate a destabilizing force from within the riverbed. This work develops a probability distribution function relating turbulent velocity fluctuations and subsurface pressure fluctuations. A cylinder was fitted with differential pressure transducers such that the pressure ports were flush with the cylinder surface and below the water-sand interface. Three-component velocities were recorded synchronously with differential pressure fluctuations measured over a 18 mm depth. As expected, results show decay in pressure fluctuations as a function of depth. The standard deviation of the pressure fluctuation in the upper hyporheic zone scales well with shear stress

Decay of Pressure Fluctuation in the Hyporheic Zone around a Cylinder

Erosion around a submerged cylinder is a well-studied problem, and is of particular interest in bridge pier scour applications. Particles erode when lift and drag forces overcome a critical threshold. These forces are typically studied from above the water-riverbed interface and are related to geometry and surficial processes. The present study maps hyporheic pressure fluctuations as they are related to surface water velocity fluctuations. Relatively, high-pressure events in the subsurface promote a destabilizing force from within the riverbed and increase the potential for the mobilization of sediment. Differential pressure transducers were fitted within a vertical cylinder in a movable bed flume. The pressure ports were flush with the cylinder surface and below the water-sand interface. The three orthogonal components of velocity were recorded synchronously with differential pressure measured over a 15 mm depth. As expected, results show decay in pressure fluctuations as a function of depth

Developing a Family of Curves for the HEC-18 Scour Equation

Accurate pier scour predictions are essential to the safe and efficient design of bridge crossings. Current practice uses empirical formulas largely derived from laboratory experiments to predict local scour depth around single-bridge piers. The resulting formulas are hindered by insufficient consideration of scaling effects and hydrodynamic forces. When applied to full-scale designs, these formula deficiencies lead to excessive over prediction of scour depths and increased construction costs. In an effort to improve the predictive capabilities of the HEC-18 scour model, this work uses field-scale data and nonlinear regression to develop a family of equations optimized for various non-cohesive soil conditions. Improving the predictive capabilities of well-accepted equations saves scarce project dollars without sacrificing safety. To help improve acceptance of modified equations, this work strives to maintain the familiar form of the HEC- 18 equation. When compared to the HEC-18 local pier scour equation, this process reduced the mean square error of a validation data set while maintaining over prediction

Developing a family of curves for the hec-18 scour equation

Accurate pier scour predictions are essential to the safe and efficient design of bridge crossings. Current practice uses empirical formulas largely derived from laboratory experiments to predict local scour depth around bridge piers. The resulting formulas are hindered by insufficient consideration of scaling effects and hydrodynamic forces. When applied to full-scale designs, these formula deficiencies lead to excessive over prediction of scour depths and increased construction costs. In an effort to improve the predictive capabilities of HEC-18, this work uses field-scale data and nonlinear regression to develop a family of equations optimized for various non-cohesive soil conditions. Improving the predictive capabilities of well-accepted equations saves scarce project dollars without sacrificing safety. To help improve acceptance of modified equations, this work strives to maintain the familiar form of the HEC-18 equation. When compared to the HEC-18 local pier scour equation, this process reduces mean square error while maintaining over prediction

St Clair River delta velocities - North, Middle and South channels

<p>Velocity data collected from the Middle Channel of the St. Clair River Delta. These data were collected using a vertically mounted ADCP, Teledyne RDI Sentinel V, 1000MHz.</p><p>The data are velocity magnitude and direction beginning 0.99m above the riverbed and a value reported every 0.5 meters of depth to within approximately 1.5 meters of the surface. </p><p> </p><p>-The instrument was set up to ping every 1 second for 120 seconds with a new collection of vertical bins collected beginning every 600 seconds.  </p><p>-Setup provides a two minute average, in each bin, every 10 minutes</p><p>'Range to Boundary' set by pressure</p><p>removed the 'side lobe interference'</p><p> </p><p>Instruments were deployed on different days but generally have data for the following period</p><p>Start Date Dec 2018 10:10 am Eastern Standard Time</p><p>End Date: April 2019 12:20 pm Eastern Standard Time</p><p> </p><p>The instruments were placed at the following coordinates:</p><p>North Channel: lat: N42.61720 Long: W82.57020 </p><p>Middle Channel: lat: N42.59983   long: W82.60316</p><p>South Channel: lat N42.58007 long: W82.56192</p&gt

St. Clair River 2007 Hydrographic Survey

<p>First multibeam hydrographic survey of the entire main stem of St. Clair River.</p><p>2007 Bathymetry data was collected by the US Army Corps of Engineers, Detroit District</p><p> </p><p>Algonac Junction Buoy to Fort Gratiot Lt.</p><p>Data were averaged into 5' x 5' grids, center placed, with limited area of 2' x 2' grid.</p><p>Data were collected with a hydrographic survey system onboard the S/V WHEELER comprised of:</p><p> </p><p>1) a Reson 8125 multi-beam at 455 kHz with a .5 degree beam width</p><p>2) a velocity profiler</p><p>3) GPS/POS MV positioning and heave, pitch and roll compensation</p><p> </p><p>This survey data set meets the requirements of EM 1110-2-1003 1 Jan 02</p><p> </p><p>Projection for all files and coordinates is NAD 83 Michigan State Plane South meters.</p><p>All depths, datums and elevations are in meters.  Elevations referenced to IGLD 85.</p><p>X Y Z Datum Elevation</p><p>x-coordinate Michigan State Plane South Meters</p><p>y-coordinate Michigan State Plane South Meters</p><p>z - depth, meters, relative to low water datum</p><p>Datum - Low Water Datum for point</p><p>Elevation - bottom elevation of river, meters, relative to IGLD85</p><p> </p&gt