Discharge Rate in White Point Swash By: Danielle Tarpley, Erin Cziraki, Vicki Green, Kelsey Fall, and JT O’Rourke

Objective CORPS of Engineers Charleston District/CCU Measure velocities, water levels in swash channels to estimate total discharge Important in understanding the volume of water flowing out and what its transporting Swashes very important

Methods Measure Across Channel Measure every 3 ft across channel Electromagnetic Current meter Tide Staff Tape Measure Measure every 3 ft across channel Collected during ebb tide

Figure 1: Graph of observed flow and depth across channel

Calculating Discharge Used tide data from Springmaid Pier Identified dates of Spring and Neap Identified times of Ebb and Flood Located data from ADCP file Calculated 15 minute averages over an hour Depth Flow 2 ebbs and 2 floods per cycle

Calculating Discharge Depth rises uniformly over channel Added 20 cm to ADCP depth Difference between ADCP depth and measured depth Difference added to sections across channel Velocity changes fractionally across channel Multiplied ADCP velocity by fraction for each section Added a section to account for increased water height

Calculating Discharge Formula: Total Discharge=Σdepth*velocity*segment width Calculated for all 8 combinations of Spring/Neap/Ebb/Flood

Results Tide Type Tidal Cycle Date Discharge(cm³/s) Discharge(m³/s) Spring Flood Oct. 27-28 28280691.32 28.28   50390930.46 50.39 Ebb 9381007.77 9.38 4577143.29 4.58 Neap Nov. 3-4 16361883.00 16.36 10850280.54 10.85 9491849.52 9.49 10591945.77 10.59

Results Comparing our measured cross section to the ADCP data: Percent Discharge (cm³/s) Discharge (cm³/s) Error 1837651.39 1738838.35 5.38