D.3 Numerical models

The TUFLOW HPC, pollutant export and TUFLOW FV models are described following.

D.3.1 TUFLOW HPC

The TUFLOW HPC model has the following general configuration:

• A 2D cell size of 50m, SGS turned on with a sample target distance of 1m
• A synthetic rainfall record applied, with a maximum daily rainfall of approximately 60mm
• Three materials, with one for each land use above
• One soil layer with constant thickness of 0.6m

All simulations use GPU.

D.3.2 Pollutant export

The pollutant export model has various forms depending on the TUFLOW CATCH configuration is simulated. Across these various forms, both Shear1 and Washoff1 methods are deployed, and other pollutant export parameters are set using the guidance provided in this manual. In all cases where applicable:

• Salinity, dissolved oxygen, silicate, adsorbed phosphorus and phytoplankton are set to constant concentrations
• Sediment and particulate organics are prohibited from infiltrating to groundwater
• Water temperature is provided as a timeseries
• Sediment uses the Shear1 method, and all other pollutants use the Washoff1 method

D.3.3 TUFLOW FV

The TUFLOW FV model has the following general configuration:

• Simulation of hydrodynamics, including density (salinity and temperature) driven processes
• Full atmospheric heat exchange simulation
• Sediment transport simulation, with one sediment fraction
• Water quality simulation, using the Organics simulation class
• 3D simulation with 8 z layers and 6 sigma layers
• Three bed materials to define sediment transport and water quality processes

All simulations use GPU.