TUFLOW CATCH Demo Models

Introduction

A demonstration model and small suite of simulations have been developed to support TUFLOW CATCH users. These simulations:

• Can be used as templates for construction of other TUFLOW CATCH simulations
• Encompass the supported TUFLOW CATCH configurations, and
• Are able to be run without a licence for TUFLOW CATCH, TUFLOW HPC or TUFLOW FV

Descriptions of the model and demonstration simulations follow.

Demonstration Project Area Domain

The demonstration model is located in New Zealand. It uses publicly available base data sets where available (with some of these being modified on occasion), and synthetic data otherwise.

The model domain is simulated under TUFLOW CATCH, which subsequently controls TUFLOW HPC and FV, for a period of 1 week from 01/01/2021 to 07/01/2021.

The catchment (represented by TUFLOW HPC) has:

• An area of approximately 55km^2.
• A relief of approximately 20m.
• Three (synthetic) land uses: urban, forest and agriculture.

The general arrangement of the catchment is presented below.

The receiving waterway, which is a hypothetical lake (represented by TUFLOW FV) has:

• An area of approximately 1km^2
• A maximum depth of approximately 12m
• Two major riverine tributaries
• Two local wastewater treatment plant discharges
• One offtake
• An overflow outlet weir

The general arrangement of the receiving waterway is presented below.

Numerical Models

The TUFLOW HPC catchment runoff / pollutant export and TUFLOW FV receiving water models are described following.

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 Module acceleration.

The pollutant export model in TUFLOW HPC has various forms depending on the TUFLOW CATCH configuration being simulated. Across these various forms, both shear1 and washoff1 methods are deployed, and other pollutant export parameters are set using the guidance provided in the TUFLOW CATCH 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

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 Module acceleration.

Suite of Demonstration Cases

The demonstration model suite includes the following simulations.

TUFLOW CATCH Demonstration Model Catalogue
Simulation Name	Description	Use case	TUFLOW CATCH Configuration
Demonstration_001.tcc	Catchment hydraulic calibration: HPC 2d outlet	Calibration of catchment hydraulic model without receiving model	TUFLOW HPC calibration only
Demonstration_002.tcc	Catchment hydraulic calibration: Pollutant export configuration with constant salinity and temperature timeseries	Calibration of catchment hydraulic model with downstream polygon	Pollutant export
Demonstration_003.tcc	Catchment pollutant calibration: Pollutant export configuration with user pollutant/s Only catchment hydraulic and pollutant export models are to be used, with non-TUFLOW FV pollutants and downstream polygon	Pollutant export
Demonstration_004.tcc	Catchment pollutant calibration: Pollutant export configuration with TUFLOW FV pollutants	Calibration of catchment pollutant export model following 002 calibration, to TUFLOW FV pollutants with downstream polygon	Pollutant export
Demonstration_005.tcc	Linked catchment and receiving model: Integrated configuration with all TUFLOW FV pollutants	Generation of first pass spatially resolved TUFLOW FV HD and pollutant boundaries for subsequent TUFLOW FV calibration initiation	Integrated
Demonstration_006.tcc	Receiving model calibration: TUFLOW FV simulation with preserved inflows	Catchment hydraulic and pollutant modelling complete (or largely so) and TUFLOW FV is to be calibrated without rerunning catchment model	Integrated
Demonstration_007.tcc	Linked catchment and receiving model: Hydrology configuration with salinity and temperature	No pollutant simulation required in TUFLOW - extend 002 above to include TUFLOW FV model	Hydrology

Data Documentation and Download

The demonstration models are fully documented in the TUFLOW CATCH manual. The associated model files are available via the TUFLOW Downloads.