# Appendix O Computed variables

The WQM’s computed variables, and the core (lowest order) constituent model class and instance where each is deployed are listed below. Output variable names are also included for cross referencing. Some TUFLOW FV variables are included in the table for completeness. With regard to naming:

• The text “NAME” in variable names is a placeholder for the user defined phytoplankton group name. “WQ_PHYTO_NAME_INT_N_MGL” list in the table would be named “WQ_PHYTO_GREEN_INT_N_MGL” if a user defined phytoplankton group name was “green”

It is recommended that this Appendix be viewed with the left hand pane table of contents hidden. Use the ‘s’ key to toggle this pane on and off. Output computed variable names are exact, and can therefore be copied and pasted directly into output blocks of control files, for example. The exception is phytoplankton variables, where the user specified group name is included within the variable name, so will need to be inserted by the user.

When interrogating three dimensional computed variable results in netcdf format, the stat field of each output file indicates whether or not a 2D cell (and hence its associated 3D column) is wet or dry. The stat field is of dimension [number of 2D cells $$\times$$ number of timesteps] and a value of zero indicates that a 2D cell (and associated 3D column) is dry. Water quality computed variables are reported as zero when 2D cells are dry, so using the stat field to filter out these dry cells is required when post processing results from models where cells wet and dry. Similarly, if viewing netcdf water quality computed variables in QGIS using the TUFLOW Viewer, QGIS’s automatic colour bar (displayed in the layer legend and properties tab) will extend to zero if the model considered includes cells that wet and dry - QGIS does not use the stat field to filter out dry cells when automatically determining colour bar ranges. The user can manually adjust this colour bar range as required. The stat field is, however, used when water quality computed variable results are viewed in plan or curtain mode in the map window when using the TUFLOW Viewer: dry cells are set to be transparent.

Table O.1: TUFLOW FV and WQ Module computed variables
Common name Notation Units Relevant element Atomic number (Z) Atomic weight (M) Output variable name Core constituent model
Dissolved oxygen $$\left[DO\right]$$ mg/L

mmol/m$$^3$$
$$O_2$$ 16 32 WQ_DISS_OXYGEN_MG_L

WQ_DISS_OXYGEN_MM_M3
Oxygen:
O2
Silicate $$\left[Si\right]$$ mg/L

mmol/m$$^3$$
$$Si$$ 16 32 WQ_SILICATE_MG_L

WQ_SILICATE_MM_M3
Silicate:
Si
Ammonium $$\left[NH_4\right]$$ mg/L

mmol/m$$^3$$
$$N$$ 7 14 WQ_AMMONIUM_MG_L

WQ_AMMONIUM_MM_M3
Inorganic nitrogen:
AmoniumNitrate
Nitrate $$\left[NO_3\right]$$ mg/L

mmol/m$$^3$$
$$N$$ 7 14 WQ_NITRATE_MG_L

WQ_NITRATE_MM_M3
Inorganic nitrogen:
AmoniumNitrate
Filterable reactive phosphorus $$\left[FRP\right]$$ mg/L

mmol/m$$^3$$
$$P$$ 15 31 WQ_FRP_MG_L

WQ_FRP_MM_M3
Inorganic phosphorus:
FRPhs
Filterable reactive phosphorus adsorbed $$\left[FRPads\right]$$ mg/L

mmol/m$$^3$$
$$P$$ 15 31 WQ_FRP_ADS_MG_L

Inorganic phosphorus:
Dissolved organic carbon $$\left[DOC\right]$$ mg/L

mmol/m$$^3$$
$$C$$ 6 12 WQ_DOC_MG_L

WQ_DOC_MM_M3
Organic matter:
Labile
Particulate organic carbon $$\left[POC\right]$$ mg/L

mmol/m$$^3$$
$$C$$ 6 12 WQ_POC_MG_L

WQ_POC_MM_M3
Organic matter:
Labile
Dissolved organic nitrogen $$\left[DON\right]$$ mg/L

mmol/m$$^3$$
$$N$$ 7 14 WQ_DON_MG_L

WQ_DON_MM_M3
Organic matter:
Labile
Particulate organic nitrogen $$\left[PON\right]$$ mg/L

mmol/m$$^3$$
$$N$$ 7 14 WQ_PON_MG_L

WQ_PON_MM_M3
Organic matter:
Labile
Dissolved organic phosphorus $$\left[DOP\right]$$ mg/L

mmol/m$$^3$$
$$P$$ 15 31 WQ_DOP_MG_L

WQ_DOP_MM_M3
Organic matter:
Labile
Particulate organic phosphorus $$\left[POP\right]$$ mg/L

mmol/m$$^3$$
$$P$$ 15 31 WQ_POP_MG_L

WQ_POP_MM_M3
Organic matter:
Labile
Refractory dissolved organic carbon $$\left[RDOC\right]$$ mg/L

mmol/m$$^3$$
$$C$$ 6 12 WQ_RDOC_MG_L

WQ_RDOC_MM_M3
Organic matter:
Refractory
Refractory dissolved organic nitrogen $$\left[RDON\right]$$ mg/L

mmol/m$$^3$$
$$N$$ 7 14 WQ_RDON_MG_L

WQ_RDON_MM_M3
Organic matter:
Refractory
Refractory dissolved organic phosphorus $$\left[RDOP\right]$$ mg/L

mmol/m$$^3$$
$$P$$ 15 31 WQ_RDOP_MG_L

WQ_RDOP_MM_M3
Organic matter:
Refractory
Refractory particulate organic matter $$\left[RPOM\right]$$ mg/L

mmol/m$$^3$$
$$C$$ 6 12 WQ_RPOM_MG_L

WQ_RPOM_MM_M3
Organic matter:
Refractory
Phytoplankton $$\left[PHY\right]$$ $$\mu$$g/L

mmol/m$$^3$$
$$C$$ (or Chl a) 6 12 WQ_PHYTO_NAME_CONC_MICG_L

WQ_PHYTO_NAME_CONC_MM_M3
Phytoplankton:
Basic
Cell density $$\rho_{PHY}$$ kg/m$$^3$$ 0 0 0 WQ_PHYTO_NAME_DENS_KG_M3 Phytoplankton:
Basic
Internal nitrogen $$\left[IN\right]$$ mg/L

mmol/m$$^3$$
$$N$$ 7 14 WQ_PHYTO_NAME_INT_N_MG_L

WQ_PHYTO_NAME_INT_N_MM_M3
Phytoplankton:
Internal phosphorus $$\left[IP\right]$$ mg/L

mmol/m$$^3$$
$$P$$ 15 31 WQ_PHYTO_NAME_INT_P_MG_L

WQ_PHYTO_NAME_INT_P_MM_M3
Phytoplankton:
Suspended sediment $$\left[SS\right]$$ mg/L SED_N
Water temperature T $$^o$$C TEMP
Nitrite $$\left[NO_2\right]$$ mg/L
mmol/m$$^3$$
$$N$$ 7 14