G.2 Wet deposition of inorganic phosphorus

Wet deposition of inorganic phosphorus includes the pluvial delivery of filterable reactive phosphorus to the water column. A global FRP concentration in rainfall is specifiable. The WQ Module multiplies this concentration by each timestep’s rainfall depth and corresponding model surface area(s) to compute the wet mass flux of FRP over each timestep (Equation (G.2)).

\[\begin{equation} F_{atm-wet}^{FRP} = \left[{FRP}\right]_{rain} \times \text{Timestep rainfall depth} \times \text{Model area} \tag{G.2} \end{equation}\]

\(\left[{FRP}\right]_{rain}\) is the specified rainfall concentration of FRP. This mass is added to the uppermost model layer cells and corresponding changes to ambient FRP concentrations computed.

If rainfall depth is specified as being spatially variable (i.e. by application of multiple atmospheric boundary conditions within TUFLOW FV), then \(F_{atm-wet}^{FRP}\) will correspondingly vary spatially.