Qual2K
Description:
QUAL2K simulates flow and water quality in simple rivers and
streams. It is typically used to assess the environmental
impact of multiple pollution discharges along rivers. Pollutants
can come from point sources such as industrial wastewater,
municipal sewers and stormwater. Pollutants can also come
from non-point sources such as agricultural or urban runoff,
and commercial activity such as forestry, mining and construction.
The model is commonly applied to support NPDES wastewater
discharge permit applications, TMDL studies on riverine systems,
and environmental impact statements for proposed development.
Capabilities:
A wide range of chemical and biological pollutants
within a river can be modeled, including carbonaceous biochemical
oxygen demand (CBOD), nitrogen and phosphorus species, suspended
solids, algae, pathogens, phytoplankton and detritus. Physical-chemical
processes simulated by the model include water quality
kinetics, chemical equilibrium, advection, dispersion, settling,
and interactions with the atmosphere (reaeration) and riverbed
(sediment oxygen demand). Water quality parameters
predicted throughout the modeled river domain include dissolved
oxygen concentration, pH, salinity and temperature, in addition
to the various pollutant quantities.
Limitations:
• One-dimensional: The river is assumed to
be fully-mixed in the vertical and lateral directions.
• Steady-state: Pollutant inputs and predicted
water quality parameters cannot evolve over time (i.e., days
or weeks), although they can vary on a diurnal cycle (i.e.,
hourly variations repeated every day).
Basic Inputs:
• River hydraulics: Channel length, elevation,
widths, slopes, roughness, for a series of discrete segments
along river domain. Flow rates for the river entering the
model, and for each pollution source.
• Rates and constants: For processes to be
simulated, e.g., CBOD decay coefficients, reaeration rate,
algal growth rate, turbulent eddy diffusivity, settling velocity.
• Pollutant source quality: Dissolved oxygen,
CBOD, nitrogen and phosphorus species, alkalinity, pH, etc.
Basic Output:
A series of graphs showing river profiles of water quality
parameter values along each modeled segment. Each water quality
parameter is shown on a separate graph.
How to Run the Model:
The model is written in MS Windows Visual Basic, and Excel
is used as the graphical user interface. All input and outputs
are organized in a series of worksheet tabs, and it is very
simple to use.
1) Enter input data into the various light
blue tabs. If available, enter observed data (e.g., for model
calibration) into the various yellow tabs.
2) In the first light blue “QUAL2K” tab, enter
a filename and directory path for saving your input data.
3) Click on the “Run” button located within any
input tab. This saves the input data, runs the model, and
generates the steady-state output profiles in tabular format
(green tabs) and graphical format (pink tabs). Output diurnal
cycles are contained in the dark blue tabs.
Developer: QUAL2K was developed by the United States Environmental Protection Agency (USEPA), which maintains a model website and publishes a Fact Sheet and Users Manual.
Faculty Contact: Gavin Gong
Application: Evaluating
a proposed treated municipal wastewater discharge into the
Housatonic River near new Milford, CT (CIEE E4252).
