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

2. 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

3. 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

4. Figure 1: Graph of observed flow and depth across channel

5. 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

6. 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

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

8. Results Tide Type Tidal Cycle Date Discharge(cm³/s) Discharge(m³/s)
Spring
Flood
Oct
28.28
50.39
Ebb
9.38
4.58
Neap
Nov. 3-4
16.36
10.85
9.49
10.59

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