Purchasing & Licensing

- Modern Intel i5 and i7's as well as Xeon systems all work with EFDC_Explorer. The faster the CPU, the better the speed.

- EFDCPlus is recommended to be run on an Intal system in order to take full advantage of the efficiency gains for the OMP (multi-threading) capabilities. For versions of EE prior to EE8, the single threaded version of EFDC_DSI works on an AMD system, but EFDC_DSI_OMP should be run on an Intel system for efficiency gains.

-  Users of EFDCPlus should run the software on a CPU with as many cores as possible. DSI uses systems with 24 threads (12 cores) using multiple Xeon chips. The more threads/cores the greater the efficiency in model run times.

- Memory is not particularly critical as the memory for the EFDCPlus and EFDC_DSI model is dynamically allocated and most models take < 250K of RAM. Four or eight gigabytes should be plenty of memory for most modeling systems.

- The application is 32 bit. It is compatible on XP, Vista, Win7, Win8 and Win10 in either 32 or 64 bit.

You can begin your purchase process by requesting a quote for EE by clicking on the “Request a Quote” icon at the left side of the webpage or by emailing ee_sales@ds-intl.biz. Once a quote is received and agreed upon, an invoice will be generated for you with payment instructions. Payment may be made via check, wire transfer or credit card. We distribute EE electronically as a download from this site to registered users. Once we receive payment, we will send you your license name, code, and installation instructions. You can then immediately begin using EE. Our support staff will assist you with any installation problems, if needed. We can also provide a CD and printed EE user information, if needed, for an additional sum.

Customers may provide payment in the form of check, wire transfer or credit card payments. To pay by credit card, please call our office at 425-728-8440 between the hours of 9am – 5pm PST.  Customers working with one of our sales partner will arrange payment directly with the partner.

Only if you buy a hardcopy of the software are there shipping charges. A flat fee is charged for this. If you choose to download your software, there is no shipping charge or any other type of delivery fee. 

Depending on your order, a sales tax may be calculated and charged. Any sales tax charged will be shown on your invoice.

We will not issue refunds of our software licenses, but we will refund customers for training events if it is within 30 days of the purchase date.

If users already have a TRIAL version of the current version of the software and purchase the software then a new license name and code will be sent to them.

A single license of EFDC_Explorer has one seat. If you wish to change computers or make significant changes to the computer you are using EE on, then you should deactivate EE and then reactivate on the new PC. If you want a site license then you should contact us about the number of seats that you require and we can negotiate a discounted price rather than buying multiple licenses for multiple offices.

DSI currently have sales partners in USA, Canada, China, Columbia, Korea, Malaysia and Vietnam. However, we are actively seeking new partners for sales of EFDC_Explorer in other regions. DSI predominantly work with companies that specialize in sales of engineering software and with particular specialization in water resources. If you are interested in becoming a sales partner of DSI please contact us at ee_info@ds-intl.biz and we will provide you with the Sales Partner Application.

Modeling in EE

We recommend you follow this checklist:


A1. Clear statement of study objectives and constraints, including schedule

A2. Area of interest and list of questions/problems to be addressed by modeling defined

A3. Site characteristics, data, and important processes identified

A4. Appropriate model chosen for items A1 to A3

i. Correct equations solved (e.g., 1D/2D/3D, mild slope, hydrostatic assumption)

ii. Important processes included (e.g., long/short waves, rising/plunging flow, stratification/lateral variation)

iii. Computational requirements defined

A5. Data for boundary conditions and validation needs defined and available/acquired

A6. Resources sufficient (i.e., money, time, staff expertise, computer resources, data for boundaries and validation)

A7. Validation criteria established consistent with A1-A6

A8. A1-A7 documented and client concurrence obtained

A9. Tier 1 and Tier 2 Analyses performed

A10. A1-A9 documented and checked by reviewer(s)

Model Setup

B1. Grid sufficiency

i. Boundary locations tested for effect on area of interest and test conditions

ii. Resolution tested by grid refinement test

iii. Bathymetry and features visually checked for accuracy

B2. Boundary conditions established appropriate to A1 – A3

B3. Initial conditions and spin-up shown to be adequate to eliminate transients

B4. B1-B3 documented and checked by separate reviewer(s)

Model Validation

C1. Adjustable parameters set within reasonable ranges of known uncertainty

C2. Model-Prototype agreement consistent with A1-A3 and A7

C3. C1-C2 documented with client concurrence and checked by reviewers(s)

Model Tests

D1. Test conditions consistent with A1-A3

D2. Sensitivity to parameters and plans tested


D3. Results consistent with expectations and other studies and within reasonable ranges

D4. D1-D3 documented with client concurrence and checked by reviewer(s)


E1. Items A-D documented in consistent understandable fashion

E2. Results expressed with appropriate confidence limits and caveats

E3. Interpretation and conclusions are consistent with A1-A3 and E2

E4. Client and reviewer(s) feedback solicited and used to refine report(s)

The model generation process is described in the EFDC_Explorer User Guide. The main points are as follows:

1. Locate a template EFDC.INP file that EFDC_Explorer will use to set many of the standard coefficients and parameters. The user can change any of these later in the model generation process. An EFDC.INP template file is required. A simple EFDC.INP was supplied in the original EFDC_Explorer setup package.

2. Bathymetry is required for the model generation process, but not required for the gridding process. Because the grid generation process is often iterative, it is recommended to skip specifying the "Topographic Information File" and, instead, use the flat bottom option in the "Elevation Options" frame.

3. Select the file containing polygons to trim the model cells (optional). The first polygon in the file should be the main model domain outline. Subsequent polygons in the file are interpreted as cutouts/islands.

4. Set the number of layers.

5. Set the initial water surface elevation. Should be above the flat bottom elevation

6. Set the default bottom roughness height.

7. Select the gridding approach and import or generate a grid. 

8. At this point the "Generate" button should be enabled. If it is still grayed out then there is still an essential piece of information that has not been set. The required inputs vary depending on the gridding option chosen. Press the "Generate" button to create a new EFDC model using the options specified. Even though a project directory is requested, this process does not write the files, only creates the model in memory.

9. When the model generation process is complete, EFDC_Explorer pops up a message informing the user as to how many active cells were created and what the maximum I and J were.

10. The last pop up displayed informs the user to review the model and make sure the I and J orientations are reasonable. For some convoluted grids, the L=2 lower left cell may not be correctly assigned. After reviewing the grid in ViewPlan and determining that the IJ mapping needs to be adjusted, the user can use the IJ mapping tools from the main EFDC_Explorer form to flip either I or J and/or transpose the I and J mapping.

11. Review the generated grid in ViewPlan. Load background images and/or polyline overlays to visually check the grid. View and check grid orthogonality.

12. If the grid is acceptable, then apply the bathymetry to this new grid using the "Bottom Elevations" button on the "Initial" conditions tab on the main EFDC_Explorer form.

13. Review the model grid with bathymetry added to make sure important bathymetric features are properly represented. Check the reasonableness of the CFL timestep.

14. Repeat these steps as necessary to obtain the proper balance of grid resolution, computational speed and other project specific factors.

Please view this step-by-step guide for viewing water quality results as an example of how to do this.

Please view this step-by-step guide for viewing age of water results as an example of how to do this.

Yes, registered users may download the EE Extraction tool from this website. Other options include:

• Use the "Export to Tecplot" feature from the PlanView

• Write your own using the formats shown in the EEXPOUT.FOR subroutine.

Yes, you can review a run in process by:

• Pausing the EFDC execution (pressing any key within EFDC_DSI will pause the execution).

• Checking the "Reload" checkbox.

• Using the ViewPlan or ViewProfile to review the model progress.

• Restart the model, if desired or stop the model run and make adjustments, save and re-run.

• Repeat as needed.

The EFDC Model

DSI have developed their own modified and improved version of EFDC called EFDCPlus (which includes what was formerly EFDC_DSI). Apart from hundreds of vital bugs fixes, the EFDC_DSI version applies dynamic memory allocation so that the user doesn’t need to manually update the array sizes for each model. Moreover, a number of significant new sub-models have been added including internal wind waves, Lagrangian particle tracking, oil spill, ice formation and melt, and the SEDZLJ sediment flume model. Multi-processing has also been integrated into EFDC_DSI which provides significant increases in speed. More detailed information is available here

DSI has developed an improved version of the EFDC code to help deal with pressure gradient errors that occur in simulations that have steep changes in bed elevation. This new version of the code is called the Sigma Zed code, or EFDC_SGZ. This contrasts with the conventional EFDC code which uses a sigma coordinate transformation in the vertical direction and uses the same number of layers for all cells in the domain. See more information on this here.

EFDC_DSI and EFDC_Explorer handles radiation shear stress for the generation of wave induced currents. However, the WEB version of EFDC_Explorer has waves disabled. At present we can only provide you with a presentation showing the capability.

To reduce possible data formatting errors, generate a simple XYZ ASCII data listing and use the DAT file extension. See Section 4.11 of the EE users guide for some more guidance.

There is documentation, examples, source code (for purchased users), as well as a YouTube channel. Simply register on our website for access to these resources. EFDC_Explorer, our pre/post processor, can generate various versions of Cartesian grids and can import a variety of grids from other sources. DSI also has developed CVLGrid, a 2D Curvilinear Grid Generator, that is especially designed to create and edit grids for use in EFDC.

The "Testcases" section of our web page has some small scan flume examples. We have used it to duplicate a number of published papers. That said, EFDC uses a hydrostatic approximation for the vertical flows. Therefore, EFDC is not to be used in cases where there is significant vertical accelerations. High energy gradients and high velocity gradients are not particularly a problem.

Drying depth does not impact results if wetting/drying is turned off. However, the HWET variable is used to shut off boundary conditions if there is too little water.

Yes, EFDC has been used in several real-time systems that DSI have developed. An example of one that is available for public access is the West Lake Real-time Hydrodynamic and Water Quality Model

Yes, it is possible to setup EFDC model on a Windows machine and then transfer the model input files to the Linux system. The Linux system will have different EFDC+ executable than Windows but uses the same input file names and the same extensions of the files. The output generated from Linux can be viewed back in EFDC_Explorer.

WASP7-EFDC Linkage

Dynamic Solutions International (DSI) has developed step-by-step procedures needed to create an EFDC hydrodynamic model results binary file (*.HYD) that is formatted for linkage as an input file to the WASP7 water quality model. The technical memorandums provided on the website provide the information needed and example problems to show the step-by-step procedures needed to successfully create and apply an EFDC project to export a hydrodynamic file (*.HYD) for linkage as an input file for a WASP7 water quality model project. The description contained in the documents assumes that the user has completed the setup of a working EFDC project for a hydrodynamic model and wishes to generate a binary HYD file as input to a WASP7 water quality model. The user is reminded that the EFDC model and the EFDC_Explorer interface includes a fully functioning coupled sediment transport and water quality model in a single EFDC model source code. The EFDC water quality model is comparable to the state variables included in the WASP7 water quality model.

Two example problems are developed by DSI to show how an EFDC model can be setup and linked to a WASP7 water quality model.

Example Problem#1. A 1D river problem for BOD, nitrogen and dissolved oxygen is setup in EFDC as a hydrodynamic, sediment transport and water quality model. The hydrodynamic results file (HYD) is then used to setup the same 1D river problem in WASP7. The results of the EFDC and WASP7 water quality models are compared to a steady state analytical model as a benchmark solution for the 1D river problem.   All input files needed for the EFDC and the WASP7 models are provided for the 1D river problem. (Download Model)

Example Problem#2. A 3D time variable lake model for hydrodynamics, sediment and water quality is setup as an EFDC model. The hydrodynamic results file (HYD) is then used to setup the same 3D lake model in WASP7. All input files needed for the EFDC and the WASP7 models are provided for the 3D lake model problem. (Download Model)

DSI recommends using the EFDC_DSI coupled hydrodynamic and water quality model instead of the EFDC/WASP linkage process because:

  1. The advantage of quicker run times for a decoupled hydrodynamic model from the water quality transport and kinetics is not valid as the WASP code alone runs 3 to 8 times SLOWER than the fully coupled EFDC_DSI model with water quality. See Table 1 for an example.
  2. The pre/post processing tools of EFDC_Explorer significantly streamline the modeling process allowing the user to spend more time in producing a better model rather than spending a lot of time with basic model/linkage mechanics.
  3. For a similarly configured water quality model, the EFDC_DSI results are nearly identical to WASP. See Figure 1.

Figure 1 River 1D dissolved oxygen (D.O.) for the analytical solution compared to the EFDC_DSI and WASP computed results. Note: The results for EFDC_DSI and WASP are nearly identical.

Table 1 EFDC_DSI and WASP runtimes.