Hydrodynamics

US EPA describes EFDC as “a state-of-the-art hydrodynamic model that can be used to simulate aquatic systems in one, two, and three dimensions. It has evolved over the past two decades to become one of the most widely used and technically defensible hydrodynamic models in the world.”  DSI has continued the development of EFDC since 1998 continuously improving the hydrodynamics and model stability while also decreasing runtimes.

Temperature

Water temperature is one of the most important physical characteristics of surface waters impacting density effects as well as thermal effects on water quality kinetics and solubility. 

EFDC+ provides a range of options to accurately simulate surface heat exchange and solar radiation attenuation in the water column.  Multiple computed evaporation options are available to better represent your system.

Salinity

Variations in salinity often impact estuarine stratification more than variations in temperature. In hundreds of studies EFDC+ has been shown to successfully predict the response of rivers and estuaries to ocean salinity due to seasonal changes in fresh water inflow and human activities, such as harbor and ship channel deepening.

Hydraulic structures

To produce a realistic simulation of actual physical conditions, you may need to account for man-made structures such bridges, sluice gates, culverts, pipes, and/or weirs.  You can simulate these structures using a standard lookup table approach or use the enhanced EFDC+ feature that uses standard hydraulic equations of typical hydraulic structures to calculate the appropriate flow for each time step.

Dye flowing through a sluice gate.

Internal Wind-waves

An advantage of EFDC+ over the EPA version of EFDC is the addition of a wind-wave sub-model is that it has been incorporated into EFDC+ hydrodynamic model. This allows for temporally and spatially varying wave conditions to be directly coupled to the EFDC+ hydrodynamics. These impacts can optionally impact just the bed shear stress or you can also model wave generated currents by the inclusion of the radiation shear stresses on the water column.

Wave Action

Waves action can have a significant impact on hydrodynamics and sediment transport. EFDC+ can be linked to external wave modeling results or wind generated waves can be internally computed.

External Wave Linkage

EFDC+ allows linkage to external wind models. EFDC+ has been enhanced to efficiently link to SWAN model output. As with the internal wind wave sub-model, you can optionally include or exclude wave generated currents.