Water Quality and Ecosystem Modeling

For more than 35 years, HydroQual (and its predecessor firm Hydroscience) has been in the forefront in the development and application of mathematical models to address the impacts of pollutant discharges on water quality and ecosystem health. The earliest receiving water models of estuarine systems were developed by one of HydroQual’s (and Hydroscience’s) co-founders, Donald J. O’Connor (1962, 1966). Another HydroQual co-founder, Robert V. Thomann (1963) was the first to develop and apply finite difference techniques (which form the basis for almost all of today’s receiving water modeling frameworks) to estuarine water quality models. O’Connor and Thomann, together with another HydroQual co-founder, Dominic DiToro, were among the first to construct modern eutrophication models (1971, 1974).

HydroQual has long been recognized nationally as innovators and developers of water quality modeling tools and computer codes. Many of the computer codes developed by HydroQual staff have become the common frameworks used by many in the modeling community. These include:

  • WASP (Water quality Analysis Simulation Program) – a generalized water quality analysis simulation program for the simulation of BOD/DO, nutrients, and phytoplankton
  • WASTOX (WASP-Toxics) a variant of the WASP program used to simulate fate and transport of toxic chemcials
  • RCA (Row Column AESOP) – a generalized water quality/ecosystem model, built on the WASP framework, but capable of being linked to 1-D, 2-D, or 3-D modern hydrodynamic models
  • SFM (Sediment nutrient Flux Model) – a framework for evaluating the interactions between the deposition of water column organic matter to the sediment bed, diagenesis, and the flux of resulting end-products (SOD and nutrients) to the overlying water column
  • BLM (Biotic Ligand Model) – a tool used to develop site-specific criteria for toxic metals
  • SYNOP – statistical rainfall analysis program

DiToro, D.M., D.J. O’Connor, and R.V. Thomann, 1971. A dynamic model of the phytoplankton population in the Sacramento San Joaquin Delta. Adv. Chem. Ser. 106, Am. Chem. Soc., Washington, D.C., pp 131-180.

O’Connor, D.J., 1962. Organic pollution of New York Harbor - Theoretical considerations. J. WPCF, 34(9), pp 905-919.

O’Connor, D.J., 1966. An analysis of the dissolved oxygen distribution in the East River. J. WPCF, 38(11), pp 1813-1830.

Thomann, R.V., 1963. Mathematical model for dissolved oxygen. J. Sanit. Engr. Div. ASCE, Vol. 89, SA5, pp 1-30.

Thomann, R.V., D.M. DiToro, and D.J. O’Connor, 1974. Preliminary model of Potomac Estuary phytoplankton. J. Envir. Engr. Div., ASCE, 100, EE3.

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