3.1 Simulation Class: DO

3.1.1 Overview

The intent of this simulation class is that it provide a relatively simple entry point to commence water quality modelling. There are many applications for this class. For example it might be used to examine basic oxygen dynamics across seasons in a water supply reservoir or a relatively newly constructed urban lake, or the potential impacts of dense desalination plant return waters on local coastal sediment oxygenation processes.

This simulation class includes only the oxygen model class as mandatory, but given oxygen’s central role in environmental processes, it provides both a solid foundation for fundamental environmental investigations, and a platform from which to expand to more advanced simulation classes. The pathogens model class can be optionally included.

**Simulation Class: DO (as an estuarine example)**

Figure 3.1: Simulation Class: DO (as an estuarine example)

3.1.2 Model Class: Oxygen

The following constituent models are available to select from within the oxygen model class.

3.1.2.1 Constituent Model: O2

The constituent model code and associated computed variables, processes and potentially interacting simulated quantities are provided in Figure 3.2 and Table 3.1. \(\newcommand{\blockindent}{\hspace{0.5cm}}\)

**Constituent model: O2**

Figure 3.2: Constituent model: O2

Table 3.1: Constituent model properties: O2
Computed Variables Units Processes Interacting Quantities
Dissolved Oxygen mg/L or mmol/m\(^3\) Atmospheric Aeration \(\cdot\quad\) Wind speed
\(\cdot\quad\) Dissolved oxygen
Sediment Flux \(\cdot\quad\) Water temperature
\(\cdot\quad\) Dissolved oxygen
\(\cdot\quad\) Sediment properties

In this relatively simple model, the only process requiring parameterisation is the sediment flux of oxygen.

3.1.3 Model Class: Pathogens (optional)

The following constituent models are available to select from within the pathogen model class.

3.1.3.1 Constituent Model: Free

The constituent model code and associated computed variables, processes and potentially interacting simulated quantities are provided in Figure 3.3 and Table 3.2.

**Constituent model: Free**

Figure 3.3: Constituent model: Free

Table 3.2: Constituent model properties: Free
Computed Variables Units Processes Interacting Quantities
Alive Pathogen CFU/100mL Settling \(\cdot\quad\) Settling model
Mortality \(\cdot\quad\) Salinity
\(\cdot\quad\) Temperature
\(\cdot\quad\) Mortality parameters
Light Inactivation \(\cdot\quad\) Light and band splitting
\(\cdot\quad\) DO
\(\cdot\quad\) Inactivation parameters
Attachment \(\cdot\quad\) Attachment parameters
Detachment \(\cdot\quad\) Attachment parameters
Dead Pathogen CFU/100mL Settling \(\cdot\quad\) Settling model
Mortality \(\cdot\quad\) Salinity
\(\cdot\quad\) Temperature
\(\cdot\quad\) Mortality parameters
Light Inactivation \(\cdot\quad\) Light and band splitting
\(\cdot\quad\) DO
\(\cdot\quad\) Inactivation parameters

3.1.3.2 Constituent Model: Attached

The constituent model code and associated computed variables, processes and potentially interacting simulated quantities are provided in Figure 3.4 and Table 3.3. This constituent model is the same as the Free constituent model, but allows for pathogens to attach to sediments.

**Constituent model: Attached**

Figure 3.4: Constituent model: Attached

Table 3.3: Constituent model properties: Attached
Computed Variables Units Processes Interacting Quantities
Alive Pathogen CFU/100mL Settling \(\cdot\quad\) Settling model
Mortality \(\cdot\quad\) Salinity
\(\cdot\quad\) Temperature
\(\cdot\quad\) Mortality parameters
Light Inactivation \(\cdot\quad\) Light and band splitting
\(\cdot\quad\) DO
\(\cdot\quad\) Inactivation parameters
Attachment \(\cdot\quad\) Attachment parameters
Detachment \(\cdot\quad\) Attachment parameters
Dead Pathogen CFU/100mL Settling \(\cdot\quad\) Settling model
Mortality \(\cdot\quad\) Salinity
\(\cdot\quad\) Temperature
\(\cdot\quad\) Mortality parameters
Light Inactivation \(\cdot\quad\) Light and band splitting
\(\cdot\quad\) DO
\(\cdot\quad\) Inactivation parameters
Attached Pathogen CFU/100mL Attachment \(\cdot\quad\) Attachment parameters
Detachment \(\cdot\quad\) Attachment parameters

Neither of the pathogen constituent models have complementary lower order computed variables, and their operation does not influence the concentrations of any other computed variables.

3.1.4 Computed variables

The only mandatory computed variable is this simulation class is dissolved oxygen, and as such the overarching simulation class network diagram is the same as that presented in Figure 3.2. If pathogens are simulated, then the corresponding simulation class network diagram is the (unconnected) aggregation of Figure 3.2 and either Figure 3.3 or Figure 3.4.