EPA Environmental Research Laboratory
College Station Road
Athens, Georgia 30613
Introduction: The Enhanced Stream Water Quality Model (QUAL2E) is applicable to well mixed, dendritic streams. It simulates the major reactions of nutrient cycles, algal production, benthic and carbonaceous demand, atmospheric reaeration and their effects on the dissolved oxygen balance. It can predict up to 15 water quality constituent concentrations. It is intended as a water quality planning tool for developing total maximum daily loads (TMDLs) and can also be used in conjunction with field sampling for identifying the magnitude and quality characteristics of nonpoint sources. By operating the model dynamically, the user can study diurnal dissolved oxygen variations and algal growth. However, the effects of dynamic forcing functions, such as headwater flows or point source loads, cannot be modeled with QUAL2E. QUAL2EU is an enhancement allowing users to perform three types of uncertainty analyses: sensitivity analysis, first order error analysis, and Monte Carlo simulation.
Purpose: The QUAL2E Windows interface was developed to make the model more user friendly. It provides input screens to facilitate preparing model inputs and executing the model. It also has help screens and provides graphical viewing of input data and model results.
Three examples with data sets are included which illustrate how to use the Windows interface to: enter the model's inputs, run the model, and plot its results. The first example is a simulation of three water quality constituents: temperature, dissolved oxygen, and ultimate carbonaceous BOD. An index screen provides easy access to the 24 input screens. After entering the data and other inputs in the input screens, users can execute the model. Graphics are accessed by clicking on the Graphics button. Three types of graphics are available: the drainage system's computational element network, flow vs. distance, and water quality constituents vs. distance. The second example illustrates how the Windows interface facilitates doing QUAL2EU uncertainty analyses. The last example preforms a dynamic (diurnal) simulation.