EFDC+ vs. Other EFDC Versions

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The Dynamic Solutions International (DSI) version of EFDC is called EFDC+ (formerly EFDC_DSI). EFDC+ is one of the most used versions of the EFDC model available to the scientific and engineering community. This article compares the capabilities of EFDC+ to other widely used EFDC models.

EFDC Model Versions

In addition to EFDC+, the two generally available EFDC models for hydrodynamic and environmental simulation are EFDC-EPA and SNL-EFDC.

EFDC-EPA is made available by the U.S. Environmental Protection Agency (EPA). Only the executable is downloadable from the EPA website. The last update available is from 2007 and while considered “open-source,” the source code is not available from EPA.
SNL-EFDC is maintained by Sandia National Laboratories (SNL). SNL-EFDC is open-source and available at Sourceforge.net. SNL-EFDC is aimed at researchers in the marine renewable energy industry, adding modeling of marine hydrokinetic energy (MHK) turbines, including turbulent kinetic energy and its dissipation. The SNL source code is based on a 2008 version of EFDC_DSI, which included DSI’s dynamic memory allocation implementation.

Learn more about the many features of EFDC+ here.

Choosing a Model

The model you choose depends in large part on project objectives, budget, schedule, and programming resources available. Here are a few things to think about:

END USE: To determine the best direction to take in choosing an EFDC version, it’s important to consider the end user. Developing a tool for regular use by a regulator or regulated will have a different set of requirements than one built by an expert for use by that expert. If the model is to be used by more than the original developer, it is important to have a user interface to assist in updating model inputs and analyzing the model results. However, if you are developing a model for your own personal use, you can determine the level of effort required to maintain and use the model.
OBJECTIVES: During the model selection process, it is important to match the computational tool, i.e. model, to the project requirements. The basic hydrodynamics are available for all versions of EFDC though there are detailed differences in available sub-options and model performance.
BUDGET: If your budget is limited, and you have programmers who can customize the code for your specific project, one of the open-source options may suffice. Keep in mind that technical support for these models is largely community-based—that is, your personal network of experts and any online forums you can find. There are no public forums or means to obtain support.
SCHEDULE: If you are building a new model, working directly with any EFDC version of the code without a user interface can take many months to years. Utilizing a software tool like EFDC_Explorer to provide a GUI and pre- and post- processing can dramatically speed up modeling efforts.
MODEL RUN TIME: Typically, model development requires multiple iterations to become fully representative of all the processes in the system, then you would need a tool that would significantly reduce your run time. EFDC+ uses the OpenMP technology which can utilize one or all of the processors on your modeling workstation. This can result in reduced model run times by a factor of four or more.
DENSITY STRATIFICATION: If you are working on a stratified water body such as an estuary, lake or harbor that has rapidly changing bathymetry, the standard EFDC vertical gridding system (Sigma stretch) may cause unrealistic vertical mixing of the water. Your model may suffer from a well-known “horizontal pressure gradient error” problem (Mellor, et.al., 1994). With the addition of Sigma-Zed sub-model in EFDC+ you can significantly reduce the horizontal pressure gradient error and better represent the vertical density structure of your system in the model.
HYDRAULIC STRUCTURES: If you need an EFDC solution that involves modeling of different hydraulic structures such as sluice gates, orifice, weirs etc., EFDC+ gives the option to easily represent such hydraulic structures anywhere in the model domain.
OIL SPILL: If you are working on a system where you need to conduct an oil spill simulation, EFDC+ provides tools to do oil spill modeling.
ICE MODELING: Are you working on colder regions where ice formation and ice melt has impact on the hydrodynamics, surface processes such as oxygen reaeration, or contaminant fate and transport? EFDC+ gives an option to represent the ice formation/melting with robust ice submodule link to the heat sub-model. Heat is conserved in the ice formation and melt process.
EFDC CUSTOMIZATION: If you need advanced features, a dedicated support team and/or do not have the time or resources to build your own custom solution, EFDC+ is the clear choice. DSI’s team will work with you to understand your project and what you are trying to achieve, and make sure you get the solution that meets your needs.
SUPPORT: The long term success of EFDC and your EFDC project may depend on continued code development and bug fixes, as well as project support. DSI manages and responds to the EFDC forums for EFDC_Explorer as well as EFDC.