Basic Modelling Concepts

Introduction

In the workflow of 3Di we distinguish a schematisation and a simulation template.

3Di Modelling Concepts

Fig. 67 The modelling concepts of 3Di

In general, the schematisation contains all information that 3Di needs for preprocessing, e.g. to create a calculation grid, and subgrid tables.

3Di Modelling Concepts part 2

Fig. 68 The modelling concepts of 3Di

The converted schematisation we call a 3Di model.

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When building a schematisation, a user has more than one version. Online we support different versions of the same schematisation. For every version, or revision, a 3Di model can be created

3Di Modelling Concepts part 4

This 3Di model needs information to run, which are initial conditions or events (e.g. rain).

To run a simulation, a user can use a simulation template or select a 3Di model and add all information required to run a simulation.

We provide all models of a simulation template based on the sqlite.

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3Di Modelling Concepts part 6

Together the ThreeDiModel, Scenario Information or Simulation Template form a Simulation

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The simulation template can either be used as is, or can be run with changes and stored as a new simulation template.

Schematisation

A detailed overview of a schematisation is given in this paragraph. It consists of:

General rasters:

  • dem_file

  • frict_coef_file

  • interception_file

Simple infiltration rasters:

  • infiltration_rate_file

  • max_infiltration_capacity_file

Interflow rasters:

  • hydraulic_conductivity_file

  • porosity_file

Ground water rasters

  • equilibrium_infiltration_rate_file

  • groundwater_hydro_connectivity_file

  • groundwater_impervious_layer_level_file

  • infiltration_decay_period_file

  • initial_infiltration_rate_file

  • leakage_file

  • phreatic_storage_capacity_file

1D elements:

  • channels

  • pipes

  • manholes

  • connection nodes

  • structures: o weirs o culverts o orifices o pumps

  • location (node id) & type (e.g. water level / discharge / etc) of boundary conditions

  • dem averaging

  • impervious surfaces & mapping

  • surfaces

  • dem refinement

  • cross section locations

  • levees & obstacles

GridSettings

  • use_2d: bool

  • use_1d_flow: bool

  • use_2d_flow: bool

  • grid_space: float

  • dist_calc_points: float

  • kmax: int

  • embedded_cutoff_threshold: float = 0.05

  • max_angle_1d_advection: float = 90.0

TableSettings

  • table_step_size: float

  • frict_coef: float

  • frict_coef_type: InitializationType

  • frict_type: int = 4

  • interception_global: Optional[float] = None

  • interception_type: Optional[InitializationType] = None

  • table_step_size_1d: float = None # actual default is set in __post_init__

  • table_step_size_volume_2d: float = None # actual default is set in __post_init__

Simulation template

A simulation template consists of:

Simulation settings:

aggregation settings ()

numerical settings

  • pump_implicit_ratio: 0,

  • cfl_strictness_factor_1d: 0,

  • cfl_strictness_factor_2d: 0,

  • convergence_cg: 0,

  • flow_direction_threshold: 0,

  • friction_shallow_water_depth_correction: 0,

  • general_numerical_threshold: 0,

  • time_integration_method: 0,

  • limiter_waterlevel_gradient_1d: 0,

  • limiter_waterlevel_gradient_2d: 0,

  • limiter_slope_crossectional_area_2d: 0,

  • limiter_slope_friction_2d: 0,

  • max_non_linear_newton_iterations: 0,

  • max_degree_gauss_seidel: 0,

  • min_friction_velocity: 0,

  • min_surface_area: 0,

  • use_preconditioner_cg: 0,

  • preissmann_slot: 0,

  • limiter_slope_thin_water_layer: 0,

  • use_of_cg: 0,

  • use_nested_newton: true,

  • flooding_threshold: 0

physical settings

  • use_advection_1d: 0,

  • use_advection_2d: 0

time step settings

  • time_step: 0,

  • min_time_step: 0,

  • max_time_step: 0,

  • use_time_step_stretch: true,

  • output_time_step: 0

Initial Water in the simulation:

  • initial_groundwater (file / global setting)

  • initial_waterlevels (file / global setting)

  • saved state

Events:

  • Dem edit

  • Breach

  • Laterals

  • DWF

  • structure controls:

    • table

    • time

    • memory

Forcings:

  • Rain

  • Wind

  • Inflow 0D (impervious surfaces & surfaces)

Workflow

In the 3Di workflow a user creates a schematisation. This schematisation consists of sqlite & rasters. The simulation template is extracted from the spatialite. The name of the simulation template is the same as the name in global settings.