Active Modules Tab

The Active Modules tab provides access to the computational and transport switches and options that are contained in C6 in EFDC.INP. These switches are the primary activation switches to specify which state variable(s) will be simulated by EFDC. Figure 1 displays the maximum number of modules currently allowed in the EFDC_Explorer/EFDC_DSI modeling system. Selecting a check box will display a new module in the left hand column, and deselecting a box will hide it.

If the Activate Cohesive Sediments or the Activate Non-Cohesive Sediment boxes have been selected the user may make changes to the sediments and sediment bed settings.

The user should first define the sediment model intended by selecting the appropriate option in the check box. Two sediment models are available by choosing either Use EFDC Sediment Model or Use SEDZLJ Sediment Model. The SEDZLJ Sediment sub-model is partially implemented in EFDC_Explorer. EFDC_Explorer can display SEDZLJ results including sediment fluxes and active layer thicknesses. However, at this time, the user cannot create, edit or view the input data. Further settings for sediments must be made in the Sediments Tab.

SEDZLJ has been developed by Sandia National Laboratories, and the SEDZLJ EFDC User Manual is downloadable from the EE website. In his paper on this sub-model, the primary developer, Scott C. James, provides a detailed description of how recently-developed sediment dynamics formulations are incorporated into the United States Environmental Protection Agency’s EFDC. The new approach is an extension of previous models and accounts for multiple sediment size classes, has a unified treatment of suspended load and bedload, and appropriately replicates bed armouring. The resulting flow, transport, and sediment dynamics model is an improvement to previous models because it may directly incorporate site-specific data, while maintaining a physically consistent, unified treatment of bedload and suspended load.

Figure 1  Active Modules Tab

The Model Selection frame shows the GVC and model selection options. EFDC_Explorer supports two EFDC models, the EFDC_GVC version (with GVC) and the EFDCPlus version.

If the EFDCPlus Model is selected the GVC Model options are not displayed. When the user selected the Use EPA GVC Model the Lagrangian Particle tracking and Wave options will be hidden.

When loading an existing model, EFDC_Explorer identifies the type of model and automatically sets the options on this tab, based on the data in the EFDC.INP file. In addition, the user can switch from one type of model to the other using the model selection option in the Model Selection frame.  When changing from one model type to the other, the user should check the model layering and boundary conditions to ensure the inputs are correct. See  the General Vertical Coordinates (GVC) page for details.

The Global Transport Options sub-frame allows the user to select from Upwind Difference, Central Difference and Experimental Upwind, as well as to use Anti-Diffusion or Anti-Diffusion Correction methods.  This option sets the same mass transport computational approach for all constituents. More granular control is available using the Details.