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River and Stream Water Quality Model (QUAL2K)
WWQTCS Info
QUAL2K (or Q2K) is a river and stream water quality model that is intended to represent a modernized version of the QUAL2E (or Q2E) model (Brown and Barnwell 1987). Q2K is similar to Q2E in the following respects:
One dimensional. The channel is well-mixed vertically and laterally.
- Steady state hydraulics. Non-uniform, steady flow is simulated.
- Diurnal heat budget. The heat budget and temperature are simulated as a function of meteorology on a diurnal time scale.
- Diurnal water-quality kinetics. All water quality variables are simulated on a diurnal time scale.
- Heat and mass inputs. Point and non-point loads and abstractions are simulated.
The QUAL2K framework includes the following new elements:
Software Environment and Interface. Q2K is implemented within the Microsoft Windows environment. It is programmed in the Windows macro language: Visual Basic for Applications (VBA). Excel is used as the graphical user interface.
- Model segmentation. Q2E segments the system into river reaches comprised of equally spaced elements. In contrast, Q2K uses unequally-spaced reaches. In addition, multiple loadings and abstractions can be input to any reach.
- Carbonaceous BOD speciation. Q2K uses two forms of carbonaceous BOD to represent organic carbon. These forms are a slowly oxidizing form (slow CBOD) and a rapidly oxidizing form (fast CBOD). In addition, non-living particulate organic matter (detritus) is simulated. This detrital material is composed of particulate carbon, nitrogen and phosphorus in a fixed stoichiometry.
- Anoxia. Q2K accommodates anoxia by reducing oxidation reactions to zero at low oxygen levels. In addition, denitrification is modeled as a first-order reaction that becomes pronounced at low oxygen concentrations.
- Sediment-water interactions. Sediment-water fluxes of dissolved oxygen and nutrients are simulated internally rather than being prescribed. That is, oxygen (SOD) and nutrient fluxes are simulated as a function of settling particulate organic matter, reactions within the sediments, and the concentrations of soluble forms in the overlying waters.
- Bottom algae. The model explicitly simulates attached bottom algae.
- Light extinction. Light extinction is calculated as a function of algae, detritus and inorganic solids.
- pH. Both alkalinity and total inorganic carbon are simulated. The river’s pH is then simulated based on these two quantities.
- Pathogens. A generic pathogen is simulated. Pathogen removal is determined as a function of temperature, light, and settling.
| Current Version |
2.07 |
|---|---|
Release Date |
March, 2007 |
Operating System |
Windows ME/2000/XP / MS Office 2000 or
Higher |
Intended Audience |
Environmental Engineers/Scientists, Regulatory
Agencies |
Key Words |
aquatic biology, assessment, compliance,
discharge, environmental effects, hydrology, NPS related, NPDES,
point source(s), surface water, test/analysis, TMDL related |
Media |
Surface Water |
Pollutant Types |
Conventional Pollutants (Nitrogen, Phosphorus,
Dissolved Oxygen, BOD, Sediment Oxygen Demand, Algae), pH, Periphyton,
Pathogens |
| File Type/Priority | Filename/Format/Size | File Description |
|---|---|---|
Install/Required |
Q2Kv2_07.zip Containing Spreadsheet Interface, Model Executable and Users Manual 3.5 MB |
This file contains the QUAL2K model and Users Manual. Note that Microsoft Excel 2000 or higher is REQUIRED to use this model. |
Optional |
QUAL2K Fact Sheet -- (PDF, 1 pp., 213KB, about PDF) |
This file contains a Fact Sheet about
the QUAL2K Modeling System in PDF Format. |
Technical Support Center fact sheet (PDF, 2 pp., 733 KB, about PDF)
TMDL fact sheet (PDF, 2 pp., 697 KB, about PDF)