The CH3D model uses a horizontally boundary-fitted curvilinear grid and a vertically sigma grid, and hence is suitable for application to coastal and nearshore waters with complex shoreline and bathymetry. The non-orthogonal grid enables CH3D to more accurately represent the complex geometry than the orthogonal grid, which is used by most other ocean circulation models. The model contains a robust turbulence closure model (Sheng and Chiu,1986; Sheng and Villaret, 1989, JGR) which enables accurate simulation of stratified flows in estuaries and lakes. Recent enhancements of the model includes modeling of aquatic vegetation, modeling of moving shoreline, addition of a sediment transport model, addition of a water quality model, and addition of a light/seagrass model, and parallel computing which leads to significant increase in computational speed. Recent applications have used horizontal grid on the order of 10-20 meters over a 200km x 50km area. A fully integrated modeling system CH3D-IMS has been developed and applied to several estuarine systems including the Indian River Lagoon, Tampa Bay, and Charlotte Harbor. The CH3D-IMS runs very efficiently - a one-year simulation takes 2-3 days. Parallel version of CH3D runs even faster on multiple-cpu shared- memory computer system such as the SGI Origin systems. Recent applications of CH3D and CH3D-IMS to integrated-scale and integrated-process modeling of large coastal and estuarine waters are summarized in Sheng et al. (2003), which appreared in Estuarine and Coastal Modeling, VIII, pp.407-422, ASCE.

CH3D-IMS, an integrated modeling system based on the curvilinear grid system of CH3D, includes circulation (CH3D), wave, sediment transport (CH3D-SED3D), water quality (CH3D-WQ3D), light attenuation (CH3D-LA), and seagrass models (CH3D-SAV). Additional processes (e.g., surface water - ground water interaction, atmospheric processes, contaminant transport, data assimilation) are being added.

CH3D-SSMS, An integrated modeling system for simulating storm surge and coastal inundation has been developed by coupling the wetting-and-drying version of CH3D with SWAN and REF/DIF. This modeling system uses the model results of a basin-scale surge model and a basin-scale wave model (for the entire Gulf of Mexico and the Western Atlantic) to provide the open boundary conditions for a coastal surge model (CH3D) and a coastal wave model (SWAN). The coastal surge model and the coastal wave model can be fully coupled or loosely coupled to produce high resolution (30-40 meters) inundation in many coastal regions (Charlotte Harbor, Tampa Bay, East Florida Coast, Biscayne Bay and Florida Bay, Northern Gulf of Mexico, and Chesapeake Bay). Results of the CH3D-SSMS can be used to (1)develop MEOW (Maximum Envelope Of Water) and MOM (Maximum of Maximum) for emergency planning, (2)develop Flood Insurance Rate Map (FIRM) for coastal counties and FEMA, (3) provide real-time forecast of surge, wave, and inundaion during a hurricane, and (4) forecast the expected beach erosion by coupling with a beach erosion model such as SBEACH.

To learn more about the CH3D and CH3D-IMS, read the CH3D and CH3D-IMS FAQ.

While CH3D and CH3D-based models have been used for conducting research in Sheng's group, other types of models have been developed and used as well. For example, we have developed a 3-D circulation model using the conservative Eulerian-Lagrangian Method (ELM) which is efficient and conservative. Unstructured grid models are also being developed. To allow ease of use in the operation of CH3D, including the generation of curvilinear grids, a GUI for CH3D is being developed. A complete Next-Generation CH3D and CH3D-IMS are expected by the end of 2004.