Oil Spill Prevention & Response
Texas Water Development Board (TWDB), in partnership with the Texas General Land Office (TGLO) Oil Spill Prevention and Response effort, maintains near real-time and forecast simulations of water circulation in the major bays for use in the event that an oil spill occurs within Texas bays. For bays with heavy ship traffic, these models quickly provide information to TGLO responders on the potential path of an oil spill by predicting water current direction and speed throughout the bay. TWDB has models for Sabine Lake, Galveston Bay, Matagorda Bay, and Corpus Christi Bay and is in the process of developing a model for San Antonio Bay.
TxBLEND Modeled Currents with Associated Winds and Tides
Matagorda Bay
TxBLEND Hydrodynamic Model for Oil Spill
Currents are computed with a hydrodynamic and salinity transport model called TxBLEND. The model was developed at Notre Dame University and was subsequently adopted, modified, and applied by TWDB to Texas' bays and estuaries. TxBLEND is a two-dimensional (vertically-averaged) finite-element model which solves the continuity equation, momentum equations, and the advection-diffusion equation for conservation of salt. The model uses unstructured, numerical grids based on the bathymetry of each bay, thus each one has different sizes and shapes so that the grid point, or nodes, vary. For example, Sabine Lake has 2,341 nodes while Corpus Christi Bay has 4,218. The computational time step for the estuaries also varies. Matagorda Bay model has a 150 second time-step, and the other estuaries have 300 second time-steps. Water velocities and depths are calculated by TxBLEND at each node for each time step, but results are displayed only every three hours within the three-day window described above, and only for the few nodal locations shown.
Currents predicted by this model are input into another type of computer model known as a trajectory model. This model, called GNOME, uses currents, winds, and other information to predict where oil will move in the near future. Oil-spill emergency response teams coordinated by the Texas General Land Office (TGLO) use information provided by these models to deploy clean-up teams and other resources to minimize a spill's impact.