US Army Corps of Engineers
Engineer Research and Development Center Website


Published Oct. 29, 2014
Biochemical cycles in the CE-QUAL-ICM

Biochemical cycles in the CE-QUAL-ICM

ADH Mesh grid used in CE-QUAL-ICM application

ADH Mesh grid used in CE-QUAL-ICM application

An Adaptable Water Quality Model with Many Applications

CE‐QUAL‐ICM (or simply ICM) is a flexible, multi‐dimensional water quality model developed by the ERDC Environmental Laboratory and suited for application in lakes, rivers, estuaries and coastal waters. ICM represents multiple biogeochemical cycles, including the aquatic carbon cycle, nitrogen cycle, phosphorus cycle and oxygen cycle. ICM also simulates physical factors, including salinity, temperature and suspended solids. The structure allows variables to be activated or inactivated and facilitates the addition of specific features required by individual projects.

Sub-models Increase Utility

The ICM code was designed for flexibility.  The code is readily modified to incorporate new modules to address new problems.  A library of sub-models, developed for previous applications, is available for additional use.  These sub-models include:

  • Sediment Diagenesis – ICM incorporates a mass‐balance model of diagenetic processes in bottom sediments. Particulate organic matter settling from the water column produces sediment oxygen demand and sediment‐water fluxes of dissolved nutrients.
  • Filter‐Feeding Benthos – ICM incorporates a mass‐balance model of filter-feeding benthos such as oysters and mussels. Filter feeders remove particles from the water column and recycle material to bottom sediments and the water. This feature allows management to project the effect of water quality improvements on living resources and has been used to project effects of living resource restoration on water quality.
  • Toxicants – Organic and inorganic toxicants have been incorporated into one ICM version. This version also incorporates features of the SEDZLJ sediment transport model. This approach is especially useful for hydrophobic contaminants, which partition to organic carbon, since ICM provides a detailed representation of carbon cycling in water and sediments.
  • Submerged Aquatic Vegetation (SAV) – ICM incorporates a SAV production model, which can be configured to represent multiple species of SAV. SAV is linked to the water column and to the bed sediments. This feature is especially useful in determining the management actions necessary to restore depleted SAV beds.
  • Carbonate Cycle - One ICM version incorporates a complete representation of the aquatic carbonate cycle and provides rigorous computations of pH, based on equilibrium chemistry.

Applications in the Field

  • Chesapeake Bay – Multiple versions have been employed here for more than 20 years. In addition to conventional water quality, ICM has been used to examine the potential for oyster restoration, the effect of planktivorous fish on algal blooms, and the relationship between SAV and water quality. Most recently, ICM was used by the Environmental Protection Agency to develop Chesapeake Bay Total Maximum Daily Loads (TMDLs), the most extensive application of the TMDL process to date.
  • San Juan Bay Estuary – This shallow tropical lagoon receives nonpoint‐source pollution from the surrounding urban area. ICM technology was readily adapted to this environment. The model was used to explore the feasibility of improving water quality through physical modifications to the estuary.
  • St. Johns River Florida – ICM was used as an aid in determining TMDLs for the tidal portion of the St. Johns River, which flows through central Florida to the Atlantic Ocean at Jacksonville. Features added to the model for this application include wind‐driven sediment resuspension, nitrogen fixation and toxic effects of salinity on freshwater SAV.
  • Saemangeum Estuary –The South Korean government is undertaking a project to reclaim 400 km2 of land from this estuary through construction of a 33 km seawall across the mouth. The remainder of the water behind the seawall will be converted into a freshwater reservoir. ICM was combined with the Regional Ocean Modelling System (ROMS) hydrodynamic model to help in interpreting and managing the environmental impacts of the development.

Cost, Distribution

The basic version of ICM is available at no cost from the ERDC point of contact listed below.  The distribution packet includes FORTRAN code, a compiled version executable on a Windows PC, and a user’s guide. 


ICM kinetics libraries have been incorporated into the Adaptive Hydrodynamics (ADH) Model. ADH is a state‐of‐the art model that operates on an unstructured mesh of (usually) triangular elements. The unstructured mesh and triangular elements provide optimal resolution in systems of complex geometry. The adaptive mesh and ADH features such as wetting and drying of shallow regions are now available to ICM.

Documentation and References

Cerco, C., and Cole, T. 1993. “Three‐dimensional eutrophication model of Chesapeake Bay,” Journal of Environmental Engineering, 119(6), 1006‐1025.

Cerco, C., and Moore, K. 2001. “System‐wide submerged aquatic vegetation model for Chesapeake Bay,” Estuaries, 24(4), 522‐534.

Cerco, C., and Noel, M. 2004. “Managing for water clarity in Chesapeake Bay,” Journal of Environmental Engineering, 130(6), 631‐642.

Cerco, C., Noel, M., and Kim, S‐C. 2006. “Three‐dimensional management model for Lake Washington: (II) Eutrophication modeling and skill assessment,” Journal of Lake and Reservoir Management, 22(2), 115‐131.

Cerco, C., and Noel, M. 2007. “Can oyster restoration reverse cultural eutrophication in Chesapeake Bay?,” Estuaries and Coasts, 30(2), 331‐343.

ERDC Points of Contact

Questions about CE-QUAL-ICM?
Contact: Dr. Carl F. Cerco, PE.
Phone: 601‐634‐4207