Abstract:

The Port of Corpus Christi Authority (PCCA) has started to deepen the Corpus Christi Ship Channel (CCSC) to a depth of -54 ft (MLLW) from the existing depth of -47 ft (MLLW) as well as widening it in select reaches. PCCA is also planning to deepen the outer reach of the ship channel (from the Gulf of Mexico to the ferry landing at Harbor Island) from the currently authorized depth of -54 ft (MLLW) to approximately -75 ft (MLLW) within the footprint of the -54 ft channel. The -54 ft channel will have -2 ft advance maintenance and -2 ft allowable overdepth, resulting in a total depth of -58 ft. Similarly, La Quinta Channel (LQC) will have a depth of -47 ft. with -2 ft advance maintenance and -2 ft allowable overdepth, resulting in a total depth of -51 ft (MLLW). These ship channel improvements would allow larger ships access to the port that will generate a positive return on investment by reducing delays and congestion and increasing the efficiency and safety of port operations. This study assesses the impacts of the ongoing and proposed channel improvement projects on storm surge water levels and inundation duration patterns in the Corpus Christi Bay system by creating and applying site-specific hydrodynamic models. The coupled hydrodynamic storm surge model Advanced CIRCulation (ADCIRC) and Simulating Waves in the Nearshore (SWAN), is used to simulate bay hydrodynamics with existing channel configurations and compared to new simulations where the channel configurations are altered in the model. Three channel configuration scenarios are used: (1) Existing Scenario (ES) representing the existing channel conditions with depth of -47 feet (MLLW); (2) Ongoing Project Scenario (OPS) representing the currently ongoing channel improvement project scenario with depth of -54 feet (MLLW) plus -4 feet for advance maintenance and allowable overdepth; and (3) Future Project Scenario (FPS) representing the proposed future channel deepening project with depth of -75 feet (MLLW) at the outer reach of CCSC from the Gulf of Mexico to Harbor Island. The hydrodynamic storm surge modeling is conducted with two synthetic Category 4 storms (Storm 319 and Storm 414) under three channel configuration scenarios (ES, OPS and FPS). The model is run in the HPC resources in the Texas Advanced Computing Center (TACC) at University of Texas at Austin. This data package contains input meshes representing three channel configurations, model parameter and setup file and modeling outputs of each channel configurations with synthetic Cat 4 storm 414 showing water surface elevation time series in the model grid (fort.63), velocity time series in the model grid (fort.64), and maximum storm surge elevation at each node during a storm event (maxele.63). Storm 414 has a forward speed nearly triple that of Storm 319, with a larger wind field and lower wind speeds, and makes landfall in the Padre Island National Seashore. Modeling results for Storm 319 are available in related dataset HI.x833.000:0017 (doi: 10.7266/ybcxw1sr).

Suggested Citation:

Subedee, Mukesh and James Gibeaut. 2023. Modeled impacts of channel dredging on storm surge produced by a Category 4 hurricanes in Corpus Christi Bay – Storm 414. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/PEB15Y1N

Purpose:

This model dataset is developed for the storm surge modeling using the coupled SWAN+ADCIRC model to assess the impacts of the ongoing and proposed CCSC improvement projects on storm surge water levels and inundation duration patterns in Corpus Christi Bay. Three models representing three channel configuration scenarios are developed representing the existing channel scenario, the ongoing channel deepening project scenario, and future channel deepening project scenario as the plan provided by the Port of Corpus Christi Authority (PCCA). Two synthetic Category 4 storms (Storm 319 and Storm 414) are forced on these three models. These storms' wind and pressure files are obtained from a storm database developed by the U. S. Army Corps of Engineers (USACE). The output datasets of the model show the storm surge water elevation and velocity in the model grid due to each storm under different channel configurations.

Data Parameters and Units:

The dataset has two folders: (1) Storm_Surge_Modeling_Input and (2) Storm_Surge_Modeling_Output. The input folder has three mesh files (files with extension .grd) representing three channel configurations (ES, OPS and FPS). It also has model setup and boundary condition files (files with extension fort.15), meteorological forcing input file (files with extension fort.22) and SWAN runtime parameter file (files with extension fort.26) for Storm 414. The output folder has three types of output files for each channel configurations (ES, OPS and FPS. They are: water elevation time series at all nodes in the model grid (files with extension fort.63); depth-averaged velocity time series at all nodes in the model grid (files with extension fort.64); and global maximum water elevation at each node in the domain (files with extension Maxele.63). The unit of output water surface elevation is meters (vertical datum: NAVD88), velocity is meters/second, and the unit of input topography and bathymetry in the input files is meters (NAVD88).

Methods:

The computational mesh used and validated for the 2019 Texas Coastal Resiliency Master Plan (TCRMP) (GLO, 2019*) is used in the coupled SWAN+ADCIRC model for the storm surge modeling in this study. The topographic data along the Texas coast in the mesh is updated with the seamless high resolution, 3-m, lidar-based Digital Elevation Model (DEM) developed for the TCRMP study (see GLO, 2019* for details). Three computational meshes depicting three channel scenarios are developed: (1) ES mesh has updated bathymetry in the mesh along the CCSC and LQC with the most recently available bathymetric channel survey data provided by USACE; (2) OPS mesh is represented by updating the ES bathymetry with the depth of -58 ft. (MLLW) along the CCSC, -18 ft. (MLLW) for the barge shelves along the CCSC and -51 ft. (MLLW) along the LQC; and (3) FPS mesh is obtained by updating the OPS mesh with -75 ft. (MLLW) along the CCSC from the Gulf of Mexico to Harbor Island. The topographic value in the mesh is same in all three meshes. The frictional roughness, represented by the Manning's n coefficients, is assigned to each land cover class derived from the Coastal Change Analysis Program (C-CAP) land cover data (https://coast.noaa.gov/digitalcoast/tools/lca.html) and National Wetland Inventory (NWI) data National Wetland Inventory (NWI) data (https://www.fws.gov/program/national-wetlands-inventory/wetlands-mapper). For more details on Manning’s n values used, how the vertical datum shift from local MLLW to NAVD88 is accounted for in the model, and other model parameters, see the technical report of 2019 TCRMP (GLO, 2019*). The model is forced using meteorological wind and pressure fields of two selected hypothetical Category 4 hurricane events: Storm 319 and Storm 414. Storm 319 is a slow moving and relatively small Category 4 hurricane making landfall near Bob Hall Pier with the forward speed of 10.47 miles/hour and maximum wind speed of 143 miles/hour, whereas Storm 414 makes landfall at Padre Island National Seashore with the forward speed of 27.27 miles/hour and maximum wind speed of 134 miles/hour. The same two hurricane events are simulated for each of the three channel depth scenarios (ES, OPS, FPS) to assess the difference in surge for the different channel configurations. Storm 319 is simulated for a total of seven days (168 hours) and the landfall occurs 132 hours into the simulation, whereas Storm 414 is simulated for 4 days (96 hours) and the landfall occurs 84 hours into the simulation. All the models are run using the High-Performance Cluster system (HPC) in the Texas Advanced Computing Center (TACC) at The University of Texas at Austin. *Texas General Land Office (GLO), 2019. Texas Coastal Resiliency Master Plan Technical Report – May 2019 https://www.glo.texas.gov/coast/coastal-management/coastal-resiliency/resources/files/2019-final_crmp_technical_report_06-14-2019.pdf

Provenance and Historical References:

Texas General Land Office (GLO), 2019. Texas Coastal Resiliency Master Plan Technical Report – May 2019 https://www.glo.texas.gov/coast/coastal-management/coastal-resiliency/resources/files/2019-final_crmp_technical_report_06-14-2019.pdf

Individual Files: