Hydraulics/Hydrodynamics

Dynamic Solutions LLC specializes in the application, development, and calibration of multi-dimensional hydraulic and hydrodynamic models. We are recognized national leaders in the use and application of the Environmental Fluid Dynamics Code (EFDC). Dynamic Solutions is the sole developer of the USEPA-licensed EFDC_Explorer pre- and post-processor software for EFDC. To enhance efficiency, Dynamic Solutions has developed many computer applications to automate several components of the model development process including: input file preparation; digital elevation model development; grid design and development; and post processing, including animation, of model results. This capability benefits our clients by reducing time and cost in model development, calibration and post processing/presentation of model results.

Modern, advanced hydrodynamic models simulate water temperature, salinity, velocity, turbulent diffusivity, and water surface elevation in time-dependent one, two or three- dimensional flow regimes. In addition to typical flow conditions, hydrodynamic and hydraulic models may also be used to simulate the effects, and consequences, of rare events such as dam failures or large storm events for risk evaluations of flood conditions. Hydrodynamic models are now routinely interfaced with sediment transport, water quality, eutrophication and toxic chemical fate models to provide transport data for the simulation of contaminant fate and transport in surface water systems.

Dynamic Solutions staff members are instructors in the theory of hydraulics and hydrodynamic models in universities and in workshops for practicing engineers. Our detailed understanding of the capabilities and limitations of specific models ensures appropriate site-specific applications to achieve the greatest benefits from each modeling project. Dynamic Solutions uses many hydraulic and hydrodynamic models including:

• EFDC (Environmental Fluid Dynamics Code)
  
• TABS
  
• HEC-2
  
• UNET
  
• HEC-RAS
  
• FLDWAV 2.0

Selected examples of our hydraulic and hydrodynamic modeling experience are described in the following project descriptions:

Hawaiian Point Source Stormwater Discharge Model. Dynamic Solutions developed a complex 3-dimensional hydrodynamic and water quality (salinity) model of the coastal waters of Hawaii. The objective of the project was to simulate the nearshore response of the salinity field to storm-induced freshwater inflows from NPDES-permitted municipal wastewater effluent discharge into the coastal ocean off Hawaii. Dynamic Solutions used the Environmental Fluid Dynamics Code (EFDC) and the EFDC_Explorer pre- and post-processor to build and calibrate a 3D model of hydrodynamics and salinity. The model incorporated the effects from freshwater inputs, tidal forcing and wind forcing. The model results were used to evaluate the storm-induced reduction of salinity and the potential adverse impacts to nearshore coral reefs.

Suwanee River and Estuary Hydrodynamic and Salinity Model. Dynamic Solutions LLC was contracted by the U.S. Geological Survey to provide EFDC_Explorer pre- and post-processor training, development of computational grid and digital elevation model and EFDC support for the development of a 3-dimensional hydrodynamic and water quality model of salinity of the Suwanee River, estuary and nearshore ocean. The Suwanee River, a shallow tidally influenced river located in northwestern Florida, discharges into the Gulf of Mexico. The domain of the EFDC model included 15 miles of the Suwanee River, ~28 miles of shore line and extended ~18 miles offshore into the Gulf of Mexico and Suwanee Sound. The model was successfully calibrated to historical records of flow and salinity.

Cahokia Restoration Modeling, USACE St. Louis District. Dynamic Solutions associates developed a HEC-RAS unsteady flow hydraulic model for the bottomland diversion canal and channel portion of the Cahokia watershed. A hydrologic model (HEC-HMS) was also developed for this 113 square mile watershed with sub-basins of the watershed in the 1 to 5 square mile range. The project also included the use of GEO-HMS and GEO-RAS. The drainage system was very complex due to many roadway culverts, bridge crossings, diversion structures, pump stations, spoil bank berms, and off channel storage areas with flap gate outlets, etc. The model is being used to better manage stormwater runoff up to the 100-year storm and restore stage fluctuations similar to the natural system that occurred before the federal levees were built to protect the interior area to the 500-year storm.

Reelfoot Lake Hydraulic Model, USACE Memphis District. Dynamic Solutions associates developed a UNET model of Reelfoot Lake, Tennessee and the Running Bayou downstream tributary channel to the junction with the Obion River. A continuous simulation watershed rainfall and runoff model (HUXRAIN) developed by the Memphis District USACE was used to compute 40 years of lake inflow data as well as downstream tributary flows.

Pictou Estuary Hydrodynamic and Sediment Transport Model, Nova Scotia
Dynamic Solutions LLC used the Environmental Fluid Dynamics Code (EFDC) to develop a 3-dimensional hydrodynamic and sediment transport model of the Pictou Estuary in Nova Scotia. The model was developed as a part of an evaluation of wasteload allocations and the water quality impacts of pollutant sources to the estuary. The Pictou Estuary receives freshwater inflows, is approximately 3.1 miles long and 2.5 miles wide. The estuary ranges in depth from 1 to 15 meters. The main objective of the study was to evaluate the feasibility and potential water quality impacts of restoring tidal flow to a section of the estuary currently isolated by a dam. Dynamic Solutions used EFDC to simulate hydrodynamics, sediment transport and sediment resuspension and deposition. A range of tidal conditions were simulated to allow prediction of suspended solids in the water column and the thickness of sediment bed deposition outside the isolated lagoon area.

Upper Housatonic River Hydrodynamic, Sediment Transport, and PCB Fate Model.
Dynamic Solutions used the Environmental Fluid Dynamics Code (EFDC) to develop a 3-dimensional advanced hydrodynamic, sediment transport, and toxic chemical model of t he Upper Housatonic River in western Massachusetts for remediation assessments of polychlorinated biphenyls (PCBs). To date, this was the most complex and sophisticated application of EFDC ever attempted by a modeling team. Prior to Dynamic Solutions’ involvement with this project, EFDC was primarily applied for much larger water bodies such as the coastal ocean, estuaries, bays, and large rivers. As part of the effort for the Housatonic River modeling project, Dynamic Solutions first independently evaluated the EFDC code for EPA through a series of reviews including the equations, algorithms, and methods used in the EFDC code; comparisons of model results to analytical benchmark tests; and comparisons of model results to various data sets collected in the laboratory and field. Dynamic Solutions coordinated significant code modifications with the developer of the EFDC code to include dynamic time-stepping and thus allow reduced computational run-times during hydrodynamic simulations of flow, sediment transport, and PCB fate in a narrow, highly meandering river like the Housatonic River. This work also required the simulation of rare out-of-bank storm events that resulted in wetting and drying of the floodplain. Our modeling approach for hydrodynamics, sediment transport, and PCB fate was evaluated and accepted by a peer review team of surface water modeling experts.