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.
QUAL2K Model Information
Current Version |
1.0 |
Release Date |
December 1, 2003 |
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 |
File Download Information
Install/Required |
QUAL2K-Setup.EXE -- Self Extracting Windows Installation File
4.3 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 Format) -- PDF File
207 KB |
This file contains a Fact Sheet about the QUAL2K Modeling System in PDF Format. |
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