Vessel-Generated Long-Wave Measurement and Prediction in Corpus Christi Ship Channel, TX

This paper discusses the analysis and results of an investigation into pressure field impacts caused by deep-draft vessel navigation on the beaches and bluffs along the Corpus Christi Ship Channel (CCSC), Corpus Christi, TX. A steady-state, 3-D hydrodynamic numerical model was modified to analyze the pressure fields generated by deep-draft vessels in the channel. The modified Vessel Generated Pressure Field (VGPF) simulates pressure field distributions and calculates water surface elevations in the channel during deep-draft vessel passage. The model incorporates the channel geometry (flat, shallow banks and deep center channel) and vessel geometry (length, beam, draft and position in channel). The vessel-generated pressure fields cause long-period water surface elevation fluctuations as large as one meter in height and 120 seconds in period. To validate the model, several field experiments were conducted that consisted of measuring the pressure waves during deep-draft vessel passage and tracking the positions and speeds of these vessels during a two-week period in August 2000. Data were collected continually during this period using a non-directional pressure gage deployed along the channel bank at elevation –2 meters (MSL). Since the channel banks are relatively flat (∼50H:1V), the water recedes far from the bluff when the drawdown passes, then rushes up in the form of long-wave runup with a bore on the leading edge. The results of the study have been used to identify the impacts of deepening the channel on shoreline stability and develop shoreline protection measures along the CCSC where pressure field effects have caused erosion of the beach and bluffs.