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Water Quality and Sediment Parameters

This section is only relevant to Water Quality Simulations.

The Water Quality Simulation Parameters govern how the engine performs the additional water quality calculations during a simulation.

It is not normally necessary to amend the Water Quality Simulation Parameters. The default values have been chosen for optimum accuracy and performance. However, these parameters can be edited if required.

To view and edit water quality simulation parameters, select Model parametersWater quality and sediment parameters from the Model menu. The water quality simulation parameters for the current network are displayed in the Object Properties Window.

Parameters

Database Table Name: hw_wq_params

Space step and Initialisation

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit

Space step multiplier

This is the maximum multiplier of the hydraulic computational mesh size used for the water quality calculations. Its purpose is to reduce the memory requirements for water quality calculations

space_step_multiplier

Long Integer

0

3

1

Number of initial state steps

This parameter is used to control the length of the water quality initialisation period for the system.

Number of initial state steps Description
-1

No initialisation (default).

The simulation engine does not carry out initialisation, the initial concentration in nodes and links is set to zero.

(Run a DWF simulation to generate an initial state for the event.)

0

Timestep initialisation.

The simulation engine sets the initial concentration in nodes and links to zero and then time steps (at the time step specified in the Initialisation timestep field) until the change in concentration at all internal nodes is less than the tolerance defined in the Initialisation tolerance field. These time steps differ from full simulation in that the engine does not perform erosion/deposition (otherwise you would not be able to achieve a steady state).

>0

Number of water quality initialisation timesteps.

The number of time steps performed with the initial water quality inputs to the system after hydraulic initialisation to steady state but before simulation is begun.

The software performs the Water Quality initial state calculation using the hydraulic steady state and the initial water inputs to the network.

Note: The use of a value > 0 is now deprecated, as initialisation does not in general achieve a realistic initial state. The ability to specify a value > 0 is retained for backwards compatibility.

If the water quality simulation is started using the final state of another simulation as the initial state of the new simulation, then this initialisation process does not occur. See Water Quality Simulations.

initial_state_steps

Long Integer

0

-1

-1

Initialisation timestep (s)

If Number of Initial State Steps is zero, the simulation uses this field as the timestep during initialisation.

initialisation_timestep

Double

2

1920

15

Initialisation tolerance

If Number of Initial State Steps is zero, the simulation uses this field as the tolerance during initialisation.

initialisation_tolerance

Double

8

1e-6

0.0000001

Trajectory and Node solver

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit

Switching iterations - trajectory solver

The iteration number at which to perform a single under-relaxation step to assist convergence.

trajectory_switching_iterations

Long Integer 0 20 1

Max iterations - trajectory solver

The maximum number of iterations allowed when generating the velocity used in the mid-point rule

trajectory_max_iterations

Long Integer 0 30 1

Absolute tolerance - trajectory solver

The iterative calculation of the mid-point is considered to have converged if the change in position of the mid-point of the trajectory from one iteration to the next is less than the Absolute Tolerance in metres.

trajectory_absolute_tolerance

Double

8 0.005

0.00000001

Relative tolerance - trajectory solver

The iterative calculation of the mid-point is considered to have converged if the change in position of the mid-point of the trajectory from one iteration to the next is less than Relative Tolerance * Trajectory Length in metres.

trajectory_relative_tolerance

Double

8 0.005

0.00000001

Max iterations - node solver

The maximum number of iterations in the network node solver to generate a Flux-Corrected Transport (FCT) solution

node_solver_max_iterations

Long Integer 0 10 1

Relative tolerance - node solver

The iterative calculation of a Flux-Corrected Transport (FCT) solution is considered to have converged when the change in concentration between two successive iterations is less than Relative Tolerance * Latest Concentration for all nodes.

node_solver_relative_tolerance

Double

8 0.001

0.00000001

Time weighting factor - node solver

The Time Weighting Factor (θ) represents the degree of implicitness in node solver discretisation:

    θ > 0.5 gives unconditional stability

    θ = 0.5 gives second order accuracy

    θ = 1 is recommended for the control of unphysical oscillations

node_solver_time_weighting

Double

3 1.0 0 1

Bed depth calculation

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit

Max iterations - bed depth

Not implemented in this version of InfoWorks ICM

bed_depth_max_iterations

Long Integer 0 20 1

Relative tolerance - bed depth

Not implemented in this version of InfoWorks ICM

bed_depth_relative_tolerance

Double

8 0.05

0.00000001

Deposition limit

The maximum amount of sediment allowed to build up in a conduit, as a proportion of flow depth. Default value is 0.1 (10%). See Sediment. Note that this only applies when erosion / deposition does not affect hydraulics.

Deposition Limit depends on the status of the Erosion / Deposition Affects Hydraulics box on the QM Parameters Dialog (accessed via the Schedule Hydraulic Run View). If the Erosion / Deposition Affects Hydraulic box is not checked, the Deposition Limit specified in the Water Quality Parameters will be used. If the box is checked, a Deposition Limit of 80% of the conduit height is used.

deposition_limit

Double

3 0.1 0 1

Bed d50

The d50 particle size for the sediment bed.

bed_d50

Double

PS 3 1 0.001

Bed specific gravity

The specific gravity of the sediment bed.

bed_s

Double

3 2.6 1

Colebrook-White

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit

Max iterations - Colebrook-White

The maximum number of iterations allowed in the Newton-Raphson non-linear solver for the friction factor in the Colebrook-White equation.

Valid values are: Maximum Iterations > 0

cw_max_iterations

Long Integer

0 20 1

Relative tolerance - Colebrook-White

The Newton-Raphson iteration for the friction factor in the Colebrook-White equation is considered to have converged when the change in the value between two successive iterations is less than Previous Value * Relative Tolerance

Valid values are: Relative Tolerance > 0

cw_relative_tolerance

Double

8 0.01

0.00000001

Washoff

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit

Build-up/washoff model

The type of build-up/washoff model used by the simulation engine.

Database Value

Help Text

Innovyze This is your chosen hydraulic runoff model .See Surface Pollutant Model and Surface Washoff and Gully Pot Flushing for further information.
SWMM SWMM Build-up/Washoff model.

washoff_model

Text 10 Innovyze

Sweep start month

This field is only enabled when the Build-up/washoff model is set to SWMM.

The month that the street sweep schedule started on can be selected from a dropdown list.

sweep_start_month Text 4 JAN
Sweep start day

This field is only enabled when the Build-up/washoff model is set to SWMM.

The day that the street sweep schedule started on.

sweep_start_day Integer 01 1 31
Sweep end month

This field is only enabled when the Build-up/washoff model is set to SWMM.

The month that the street sweep schedule finished on an be selected from a dropdown list.

sweep_end_month Text 4 DEC 1 31
Sweep end day

This field is only enabled when the Build-up/washoff model is set to SWMM.

The day that the street sweep schedule finished on.

sweep_end_day Integer 1 31
Non-attached pollutants

This field is only enabled when the Build-up/washoff model is set to SWMM.

This field contains a series of records defining the non attached pollutants.

The records are entered on the Non-attached pollutants grid which is displayed by clicking on the button.

Database Table Name: hw_na_pollutants

Field Name

Help Text

Database Field

Data Type

Size

Units

Precision

Default

Error Lower Limit

Error Upper Limit

Warning Lower Limit

Warning Upper Limit

Determinant The name of the determinant can be selected from a list. determinant Text 3
Rainfall concentration

The concentration of pollutant in rainfall, in mg/l or 1/l, depending on the determinant.

roundwater_conc Double 0 0 0
Groundwater concentration

The concentration of pollutant in groundwater, in mg/l or 1/l, depending on the determinant.

rainfall_conc Double 0 0

RDII concentration

The concentration of the pollutant in RDII (Rainfall Derived Inflow and Infiltration), in mg/l or 1/l, depending on the determinant.

rdii_conc Double 0 0
Build up only during snowfall A check indicates that the build up of the specified determinate only occurs during snowfall. Unchecked by default. snow_build_up Boolean False
na_pollutants Structure
Potency factors

This field is only enabled when the Build-up/washoff model is set to SWMM.

This field contains a series of records defining the Potency factors.

The records are entered on the Potency factors grid which is displayed by clicking on the button.

Database Table Name: hw_pot_factors

Field Name

Help Text

Database Field

Data Type

Size

Units

Precision

Default

Error Lower Limit

Error Upper Limit

Warning Lower Limit

Warning Upper Limit

Determinant The name of the determinant (co-pollutant) can be selected from a list. determinant Text 4
Sediment fraction The sediment fraction can be selected from a list. sediment_fraction Text 4
Potency factor Fraction of co-pollutant concentration potency_factor Double 0 0 1

pot_factors Structure

1D erosion/deposition model

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit

Erosion/deposition model

Choose the 1D erosion/deposition model used by the simulation engine.

See Conduit Model for further details.

Database Value

Help Text

Ackers-White

Ackers White Model

Velikanov

Velikanov Model

KUL

KUL Model

erosion_model

Text

12 0

Ackers-White

Active layer depth method (1D)

Method of determining active layer depth:

Database Value

Help Text

Explicit Use value specified in the Active layer depth field.
D50 Active layer thickness is calculated as d50 material size multiplied by Active layer depth factor.
D90 Active layer thickness is calculated as d90 material size multiplied by Active layer depth factor.
aldepth_method_1D Text 12 D50

2D erosion/deposition model

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit
Calibration coefficient Calibration coefficient to adjust the 2D sediment carrying capacity of the flow calibration Double 3 1 0
Active layer depth method

Method of determining active layer depth:

Database Value

Help Text

Constant Use value specified in the Active layer depth field.
D50 Active layer thickness is calculated as d50 material size multiplied by Active layer depth factor.
D90 Active layer thickness is calculated as d90 material size multiplied by Active layer depth factor.
aldepth_method Text 12 0 Constant
Active layer depth

Active layer thickness.

Applicable when Active layer depth method is set to Constant. 		aldepth Double Y 3
Active layer depth factor

Multiplying factor for calculating active layer thickness.

Applicable when Active layer depth method is set to D50 or D90.

aldepth_factor Double 3
Model type

Model type of the 2D Erosion-deposition model:

Database Value

Help Text

Total Load 2D Erosion-deposition model includes bed and suspended sediment loads.
Suspended Load

2D Erosion-deposition model includes only suspended sediment load unless bed load is also being modelled.

model_type Text 14 0
Total load model

Total load model used in the 2D Erosion-deposition model.

See 2D Sediment Transport Equations for details.

Database Value

Help Text

Ackers-White Ackers-White model
Ackers-White revised Ackers-White revised model
Engelund-Hansen Engelund-Hansen model
Westrich-Jurashek Westrich-Jurashek model
Van Rijn Van Rijn model
Velikanov Velikanov model
total_load_model Text 20 0 Ackers_White revised
Equilibrium near-bed concentration

Formulation to estimate the equilibrium near bed concentration used for suspended load only calculations in the 2D Erosion-deposition model.

See 2D Sediment Transport Equations for details.

Database Value

Help Text

Van Rijn Van Rijn formulation
Zyserman and Fredsoe Zyserman and Fredsoe formulation
Smith and McLean Smith and McLean formulation
nbconc_method Text 20 0 Van Rijn
Near-bed concentration

Formulation to estimate the near-bed concentration used for suspended load only calculations in the 2D Erosion-deposition model.

See 2D Sediment Transport Equations for details.

Database Value

Help Text

Rouse profile Approximation of the Rouse profile
Lin Lin formulation
nbconc Text 20 0 Rouse profile
Skin friction method

Skin friction calculation method.

See 2D Sediment Transport Equations for details.

Database Value

Help Text

Manning Manning formulation
Manning-Strickler Manning-Strickler formulation
Dawson Dawson formulation
Soulsby Soulsby formulation
Logarithmic Logarithmic formulation
Nikuradse Nikuradse formulation
skinfric_method Text 20 0 Manning
Limit erosion rate Check this option to impose an upper limit on the rate of erosion of suspended load. limit_erosion_rate Boolean 0 0
Max erosion rate

Enabled if Limit erosion rate is checked.

Rate of erosion of suspended sediment will be limited to the value specified.

The limitation will be applied to each sediment fraction in the case of independent fractions, or to the composite erosion rate for dependent fractions.

max_erosion_rate Double ERODERATE 3 0.0
Limit deposition rate Check this option to impose an upper limit on rate of deposition of suspended load. limit_deposition_rate Boolean 0 0
Max deposition rate

Enabled if Limit deposition rate is checked.

Rate of deposition of suspended sediment will be limited to the value specified.

The limitation will be applied to each sediment fraction in the case of independent fractions, or to the composite erosion rate for dependent fractions.

max_deposition_rate Double ERODERATE 3 0.0

2D bed load model

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit
Calibration coefficient Calibration coefficient to adjust the 2D bed load carrying capacity of the flow. bedload_calibration Double 3 1 0
Bed load formula

Bed load formula used in the 2D Bed Load model.

See 2D Sediment Transport Equations for details.

Database Value

Help Text

Meyer-Peter-Müller Meyer-Peter Müller formula
Wong and Parker Wong and Parker formula
Van Rijn Van Rijn formula
Einstein-Brown Einstein-Brown formula
User defined User defined formula
bedload_formula Text 20 0 Meyer-Peter-Müller
Critical Shields method

Method to calculate the critical Shields parameter.

Not applicable if Bed load formula is set to Einstein-Brown.

See 2D Sediment Transport Equations for details.

Database Value

Help Text

User defined Specify a value in the Critical Shields parameter field
Shields curve Critical Shields given by a parameterisation of the Shields curve.
critical_shields_method Text 15 0 User defined
Critical Shields parameter

Applicable if Critical Shields method is set to User defined.

critical_shields Double Y 3 0.047 0
Coefficient K

Applicable if Bed load formula is set to User defined.

k_coefficient Double 3 12, which corresponds to Nielsen method 0
Coefficient A

Applicable if Bed load formula is set to User defined.

a_coefficient Double 3 0, which corresponds to Nielsen method. 0
Coefficient B

Applicable if Bed load formula is set to User defined.

b_coefficient Double 3 1, which corresponds to Nielsen method. 0
Exponent 1

Applicable if Bed load formula is set to User defined.

exp1_coefficient Double 3 0.5, which corresponds to Nielsen method. 0
Exponent 2

Applicable if Bed load formula is set to User defined.

exp2_coefficient Double 3 0.5, which corresponds to Nielsen method. 0
Exponent 3

Applicable if Bed load formula is set to User defined.

exp3_coefficient Double 3 1, which corresponds to Nielsen method. 0
Exponent 4

Applicable if Bed load formula is set to User defined.

exp4_coefficient Double 3 1, which corresponds to Nielsen method. 0
Exponent 5

Applicable if Bed load formula is set to User defined.

exp5_coefficient Double 3 1, which corresponds to Nielsen method. 0
Exponent 6

Applicable if Bed load formula is set to User defined.

exp6_coefficient Double 3 1, which corresponds to Nielsen method. 0

Sediment fraction 1 and Sediment fraction 2

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit
d16 of sf1

Applicable if Model type is set to Suspended load and Equilibrium near-bed concentration is set to Van Rijn.

The d16 particle size of Sediment Fraction 1.

d16_sf1 Double PS 3 0
d35 of sf1

Applicable if Model type is set to Total load and Total load model is set to Ackers-White or Ackers-White revised.

The d35 particle size of Sediment Fraction 1.

d35_sf1 Double PS 3 0

d50 of sf1

The d50 particle size of Sediment Fraction 1

Applicable to all erosion/deposition models

d50_sf1

Double

PS 3 0.001
d84 of sf1

Applicable if Model type is set to Suspended load and Equilibrium near-bed concentration is set to Van Rijn.

The d84 particle size of Sediment Fraction 1.

d84_sf1 Double PS 3 0
d90 of sf1

Applicable if:

  • Active layer depth is set to D90
  • Model type is set to Total load and Total load model is set to Van Rijn.

The d90 particle size of Sediment Fraction 1.

d90_sf1 Double PS 3 0

Specific gravity of sf1

The Specific Gravity of Sediment Fraction 1

Applicable to all erosion/deposition models

s_sf1

Double

3 1

1D settling velocity of sf1

The settling velocity of Sediment Fraction 1

Applicable to all erosion/deposition models

settling_velocity_sf1

Double

3 0

Critical erosion efficiency for sf1

Velikanov model only

eta1_sf1

Double

8

0.00225

0

Critical deposition efficiency for sf1

Velikanov model only

eta2_sf1

Double

8

0.00275

0

Alpha deposition for sf1

Alpha deposition parameter for Sediment Fraction 1

Applicable to KUL model only

alpha_deposition_sf1

Double

5 0

Beta deposition for sf1

Beta deposition parameter for Sediment Fraction 1

Applicable to KUL model only

beta_deposition_sf1

Double

3 1

Gamma deposition for sf1

Gamma deposition parameter for Sediment Fraction 1

Applicable to KUL model only

gamma_deposition_sf1

Double

3 0

Alpha erosion for sf1

Alpha erosion parameter for Sediment Fraction 1

Applicable to KUL model only

alpha_erosion_sf1

Double

5 0

Beta erosion for sf1

Beta erosion parameter for Sediment Fraction 1

Applicable to KUL model only

beta_erosion_sf1

Double

3 1

Gamma erosion for sf1

Gamma erosion parameter for Sediment Fraction 1

Applicable to KUL model only

gamma_erosion_sf1

Double

3 0
Density of sf1 Density of Sediment Fraction 1 dens_sf1 Double DENSITY 3 1700
2D sf1 settling velocity calculation

Method used to estimate settling velocity of Sediment Fraction 1.

See 2D Sediment Transport Equations for details.

Database Value

Help Text

User

Use value specified in 2D sf1 settling velocity.

Van Rijn Van Rijn method
Soulsby Soulsby method
Wu and Wang Wu and Wang method
Hallermeier Hallermeier method
Zanke Zanke method
settling_calc_sf1 Text 12 0 User
2D sf1 settling velocity

Applicable when 2D sf1 settling velocity calculation set to User.

Settling velocity of Sediment Fraction 1.

2D_settling_velocity_sf1 Double SETVEL 3
Corey shape factor of sf1

Corey shape factor of Sediment Fraction 1.

Measures the sphericity of sediment grains.

corey_shape_factor_sf1 Double 3 0.7 0.3 0.9
Porosity of sf1 Porosity of Sediment Fraction 1 porosity_sf1 Double 3 0.375 0 1
Skin roughness parameter of sf1

Skin roughness parameter of Sediment Fraction 1.

Relates the Nikuradse equivalent grain roughness with the sediment diameter.

roughness_sf1 Double 3 2.5 0
Angle of repose of sf1 Maximum angle that sediment can accumulate at and remain stable. repose_sf1 Double ANGLE 2 90 0 90
d16 of sf2

Applicable if Model type is set to Suspended load and Equilibrium near-bed concentration is set to Van Rijn.

The d16 particle size of Sediment Fraction 2.

d16_sf2 Double PS 3 0
d35 of sf2

Applicable if Model type is set to Total load and Total load model is set to Ackers-White or Ackers-White revised.

The d35 particle size of Sediment Fraction 2.

d35_sf2 Double PS 3 0

d50 of sf2

The d50 particle size of Sediment Fraction 2

Applicable to all erosion/deposition models

d50_sf2

Double

PS 3 0.001
d84 of sf2

Applicable if Model type is set to Suspended load and Equilibrium near-bed concentration is set to Van Rijn.

The d84 particle size of Sediment Fraction 2.

d84_sf2 Double PS 3 0
d90 of sf2

Applicable if:

  • Active layer depth is set to D90
  • Model type is set to Total load and Total load model is set to Van Rijn.

The d90 particle size of Sediment Fraction 2.

d90_sf2 Double PS 3 0

Specific gravity of sf2

The Specific Gravity of Sediment Fraction 2

Applicable to all erosion/deposition models

s_sf2

Double

3 1

1D settling velocity of sf2

The settling velocity of Sediment Fraction 2

Applicable to all erosion/deposition models

settling_velocity_sf2

Double

3 0

Critical erosion efficiency for sf2

Velikanov model only

eta1_sf2

Double

8

0.00225

0

Critical deposition efficiency for sf2

Velikanov model only

eta2_sf2

Double

8

0.00275

0

Alpha deposition for sf2

Alpha deposition parameter for Sediment Fraction 2

Applicable to KUL model only

alpha_deposition_sf2

Double

5 0

Beta deposition for sf2

Beta deposition parameter for Sediment Fraction 2

Applicable to KUL model only

beta_deposition_sf2

Double

3 1

Gamma deposition for sf2

Gamma deposition parameter for Sediment Fraction 2

Applicable to KUL model only

gamma_deposition_sf2

Double

3 0

Alpha erosion for sf2

Alpha erosion parameter for Sediment Fraction 2

Applicable to KUL model only

alpha_erosion_sf2

Double

5 0

Beta erosion for sf2

Beta erosion parameter for Sediment Fraction 2

Applicable to KUL model only

beta_erosion_sf2

Double

3 1

Gamma erosion for sf2

Gamma erosion parameter for Sediment Fraction 2

Applicable to KUL model only

gamma_erosion_sf2

Double

3 0
Density for sf2 Density of Sediment Fraction 2 dens_sf2 Double DENSITY 3 1700
2D sf2 settling velocity calculation

Method used to estimate settling velocity of Sediment Fraction 2.

See 2D Sediment Transport Equations for details.

Database Value

Help Text

User

Use value specified in 2D sf2 settling velocity.

Van Rijn Van Rijn method
Soulsby Soulsby method
Wu and Wang Wu and Wang method
Hallermeier Hallermeier method
Zanke Zanke method
settling_calc_sf2 Text 12 0 User
2D settling velocity of sf2

Applicable when 2D sf2 settling velocity calculation set to User.

Settling velocity of Sediment Fraction 2.

2D_settling_velocity_sf2 Double SETVEL 3
Corey shape factor of sf2

Corey shape factor of Sediment Fraction 2.

Measures the sphericity of sediment grains.

corey_shape_factor_sf2 Double 3 0.7 0.3 0.9
Porosity of sf2 Porosity of Sediment Fraction 2 porosity_sf2 Double 3 0.375 0 1
Skin roughness parameter of sf2

Skin roughness parameter of Sediment Fraction 2.

Relates the Nikuradse equivalent grain roughness with the sediment diameter.

roughness_sf2 Double 3 2.5 0

Critical erosion efficiency composite

Velikanov model only

eta1_composite

Double

8

0.00225

0

Critical deposition efficiency composite

Velikanov model only

eta2_composite

Double

8

0.00275

0

Alpha deposition composite

KUL model only

alpha_deposition_composite

Double 5 0

Beta deposition composite

KUL model only

beta_deposition_composite

Double 3 1

Gamma deposition composite

KUL model only

gamma_deposition_composite

Double 3 0

Alpha erosion composite

KUL model only

alpha_erosion_composite

Double 5 0

Beta erosion composite

KUL model only

beta_erosion_composite

Double 3 1

Gamma erosion composite

KUL model only

gamma_erosion_composite

Double 3 0
Angle of repose of sf2 Maximum angle that sediment can accumulate at and remain stable. repose_sf2 Double 2 90 0 90

2D Diffusion coefficients

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit
Diffusion coefficients

Click the button to display the Diffusion Coefficients Grid.

The grid allows one diffusion coefficient to be set per sediment fraction and per dissolved pollutant.

If no diffusion coefficient is specified in this table for a specific pollutant, the 2D engine will only transport it. There will not be any diffusion.

Field Help Text
Pollutant or sediment The type of pollutant or sediment can be selected from a drop-down list.
Diffusion coefficient (m2/s) The diffusion coefficient which is to be applied to the selected pollutant or sediment.

The diffusion coefficients defined in this grid are used by the 2D water quality engine only. See 1D Diffusion for Water Quality Simulations for information about the 1D diffusion coefficients.

dcp Structure 0

Decaying pollutant parameters

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit
Decaying pollutants

Click the button to display the Decaying Pollutants Grid.

The grid allows decay settings for a set of pollutants to be entered.

Field Help Text
Determinant

Select determinant to which decay is to be applied.

Decay type

The following decay types are available:

Decay Type Equation
None -
Linear
Exponential concentration
Exponential time
Exponential both

Where:

  • v is the determinant value, mg/l or cfu/100ml *
  • a is the constant decay rate or maximum decay rate depending on decay type, (mg/l)/day or (cfu/100ml)/day *
  • b is the exponential decay, 1/(mg/l) or 1/(cfu/100ml) *

* depending on the selected determinant

  • c is the exponential decay constant, (1/day)
  • dt is the simulation engine timestep, s
Constant decay rate Parameter used in decay type equations above
Maximum decay rate Parameter used in decay type equations above
Exponential decay Parameter used in decay type equations above
Exponential decay constant Parameter used in decay type equations above
dpp Array

Dissolved oxygen parameters

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit
Calculate reaeration parameters Calculate reaeration rate kair directly as a function of water depth and velocity reaer_calc_params Boolean
Reaeration coefficient Reaeration coefficient reaer_coeff Double RE 3 0.04
Reaeration temperature coefficient Temperature dependency factor for reaeration reaer_temp_coeff Double 3 1.16
Structure aeration coefficient Reaeration coefficient at structures structure_aer_coeff Double 3 0
UOD rate constant at 20C Ultimate Oxygen Demand decay parameter: rate constant at 20°C (day-1) bod5_20c_decay_rate Double PDR 3 0.23
UOD temperature coefficient Ultimate Oxygen Demand decay parameter: temperature coefficient bod5_temp_coeff Double 3 4.7
Organic nitrogen rate constant at 20C Organic nitrogen decay parameter: rate constant at 20°C (day-1) org_nitr_20c_decay_rate Double PDR 3 0.23
Organic nitrogen temperature coefficient Organic nitrogen decay parameter: temperature coefficient org_nitr_temp_coeff Double 3 4.7
Ammonia rate constant at 20C Ammonia oxidation parameter: rate constant at 20°C (day-1) ammonia_20c_decay_rate Double PDR 3 0.26
Ammonia temperature coefficient Ammonia oxidation parameter: temperature coefficient ammonia_temp_coeff Double 3 4.7
Salinity coefficient Ammonia oxidation parameter: salinity coefficient salinity_coeff Double 3 0
Base salinity Ammonia oxidation parameter: base salinity base_salinity Double MCSI 3 0
Suspended solids coefficient Ammonia oxidation parameter: base suspended solids coefficient suspended_solids_coeff Double 3 0
Base suspended solids Ammonia oxidation parameter: base suspended solids base_suspended_solids Double PC 3 0
Base suspended solids factor Ammonia oxidation parameter: multiplication factor for base suspended solids base_susp_solids_factor Double 3 0
Nitrite to nitrate rate constant at 20C Nitrite to nitrate oxidation parameter: rate constant at 20°C (day-1) no2_20c_decay_rate Double PDR 3 1.0
Nitrite to nitrate temperature coefficient Nitrite to nitrate oxidation parameter: temperature coefficient no2_temp_coeff Double 3 5.0

Salt parameters

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit
Constant concentration Salt concentration to be used in the absence of profile data salt_const_conc Double 3 0

Temperature parameters

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit
Heat transfer coefficient Heat exchange coefficient at water surface temp_heat_transfer_coeff Double HT 3 0
Equilibrium water temperature Temperature at which there is no heat transfer between the air and the water temp_equilib_water_temp Double CF 3 20
Constant temperature Water temperature to be used in the absence of profile data temp_constant_temp Double CF 3 20

Coliforms parameters

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit
T90

Time taken for 90% of the original population to decay during the day.

If a rainfall event includes a solar radiation profile, and if the radiation at the current time is non-zero, the specified T90 value will be used in the simulation; otherwise the T90 night value will be used.

If a rainfall event does not include a solar radiation profile, the specified T90 night value will be used in a simulation.

Note that for pre ICM 2021.1 model networks, T90 night = T90.

coliforms_t90 Double HOURS 3 10
T90 night

Time taken for 90% of the original population to decay during the night.

See the description of T90 or further information.

coliforms_t90_night Double HOURS 3 10

User defined process parameters

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit
User defined processes

Click the button to display the Process Definitions Grid.

Each named process may act on one or more determinants; click the button on User processes to create a set of determinants and factors for the process.

Field Help Text
Process name

Identifier for the process

Process type

The following process types are available:

Process Type Equation
Growth Rate = s1 x P x p2(s2-p3) x s3/(s3-p4)
Growth-product Rate = P x p2 x s1 x s2
Equilibrium Rate = P x (p1 - s1)

Where:

  • P is a parameter that is either a constant or a variable selected from the Scaling factor type dropdown list.

    If a constant, P will be p1 for Growth and Growth-product or p2 for Equilibrium

    If a variable:

  • p1 to p7 are coefficients 1 to 7
  • s1 to s6 are concentrations of determinants 1 to 6
Scaling factor type

A scaling factor used in the process. The factor can be set to:

  • Constant
  • Variable
Determinant 1 Determinant used in the process type equations above
Determinant 2

Determinant used in the process type equations above

Disabled if Process type = Equilibrium and Scaling factor type = Constant or Variable

Determinant 3

Determinant used in the process type equations above

Disabled if Process type = Growth-product or Equilibrium and Scaling factor type = Constant or Variable

Determinant 4

Determinant used in the process type equations above

Disabled if Process type = Growth, Growth-product or Equilibrium and Scaling factor type = Constant

Determinant 5

Determinant used in the process type equations above

Disabled if Process type = Growth, Growth-product or Equilibrium and Scaling factor type = Constant

Determinant 6

Determinant used in the process type equations above

Disabled if Process type = Growth, Growth-product or Equilibrium and Scaling factor type = Constant

Coefficient 1

Parameter used in process type equations above

Disabled if Process type = Growth or Growth-product and Scaling factor type = Variable

Coefficient 2

Parameter used in process type equations above

Disabled if Process type = Equilibrium and Scaling factor type = Variable

Coefficient 3

Parameter used in process type equations above

Disabled if Process type = Growth-product or Equilibrium and Scaling factor type = Constant or Variable

Coefficient 4

Parameter used in process type equations above

Disabled if Process type = Growth-product or Equilibrium and Scaling factor type = Constant or Variable

Coefficient 5

Parameter used in process type equations above

Disabled if Process type = Growth, Growth-product or Equilibrium and Scaling factor type = Constant

Coefficient 6

Parameter used in process type equations above

Disabled if Process type = Growth, Growth-product or Equilibrium and Scaling factor type = Constant

Coefficient 7

Parameter used in process type equations above

Disabled if Process type = Growth, Growth-product or Equilibrium and Scaling factor type = Constant

User processes

Click the button to display the User Processes Grid.

The grid is used to create a set of determinants and factors for the process.

Field Help Text
Determinant Water quality determinant to which process is to be applied
Factor Multiplying factor
udp Array

Structure parameters

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit
Structures

Click the button to display the Structures Grid.

Set reaeration coefficients for a set of controls (excluding pumps) in the network. These values override the Structure aeration coefficient in the dissolved oxygen parameters.

sp Array

Dissolved algae parameters

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit
Nitrate uptake (half saturation) Half saturation constant for nitrate uptake phy_n_uptake_half_sat Double PC 3 0.1 0
Phosphate uptake (half saturation) Half saturation constant for phosphate uptake phy_p_update_half_sat Double PC 3 0.014 0
Silicate uptake (half saturation) Half saturation constant for silicate uptake phy_s_uptake_half_sat Double PC 3 0.0 0
Nitrogen to carbon ratio Nitrogen to carbon ratio phy_n_c_ratio Double 3 0.16 0
Phosphorus to carbon ratio Phosphorus to carbon ratio phy_p_c_ratio Double 3 0.024 0
Silicon to carbon ratio Silicon to carbon ratio phy_s_c_ratio Double 3 0.01 0
Gradient below critical temperature Maximum productivity parameter - gradient below critical temperature phy_grad_low_temp Double 3 0.017
Intercept below critical temperature Maximum productivity parameter - intercept below critical temperature phy_int_low_temp Double 3 -0.025
Gradient above critical temperature Maximum productivity parameter - gradient above critical temperature phy_grad_high_temp Double 3 0.037
Intercept above critical temperature Maximum productivity parameter - intercept above critical temperature phy_int_high_temp Double 3 -1.564
Critical temperature Maximum productivity parameter - critical temperature phy_crit_temp Double CF 3 25.0 -100 100
Solar radiation (maximum productivity) Solar radiation for maximum productivity phy_pmax_solar_rad Double SR 3 277.778 0.001
Light extinction factor Light extinction factor due to phytoplankton phy_light_ext_factor Double 3 0.85
Respiration rate at 20C Respiration rate at 20°C phy_resp_rate_20 Double PDR 3 0.02
Respiration Q10 Q10 value for respiration of phytoplankton phy_resp_q10 Double 3 2.2 0.001
Mortality rate Mortality rate constant for phytoplankton phy_mort_rate Double PDR 3 0.1

Detrital carbon parameters

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit
Decay constant at 20C Decay constant at 20°C phy_decay_20 Double PDR 3 0.046
Temperature dependency Factor for temperature dependence phy_temp_dep Double 3 4.7
Settling velocity Settling velocity for detrital carbon phy_sett_vel Double SETTL 3 0..001 0

Adsorbed phosphorus parameters

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit
Adsorption rate at 20C Adsorption rate at 20°C ad_rate_20 Double PDR 3 25.0
Temperature dependence factor Temperature dependence factor temp_dep_factor Double 3 0.0
Saturation adsorption ratio Saturation adsorption ratio of phosphate to mud sat_ad_ratio Double 3 0.05
Half saturation (Langmuir isotherm) Half saturation constant for Langmuir isotherm half_sat_langmuir Double PC 3 0.5 0

Attached algae parameters

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit
Nitrate uptake (half saturation) Half saturation constant for nitrate uptake ben_n_uptake_half_sat Double PC 3 0.1 0
Phosphate uptake (half saturation) Half saturation constant for phosphate uptake ben_p_uptake_half_sat Double PC 3 0.014 0
Silicate uptake (half saturation) Half saturation constant for silicate uptake ben_s_uptake_half_sat Double PC 3 0.0 0
Nitrogen to carbon ratio Nitrogen to carbon ratio ben_n_c_ratio Double 3 0.16 0
Phosphorus to carbon ratio Phosphorus to carbon ratio ben_p_c_ratio Double 3 0.024 0
Silicate to carbon ratio Silicate to carbon ratio ben_s_c_ratio Double 3 0.0 0
Solar radiation (maximum productivity) Solar radiation for maximum productivity ben_pmax_solar_rad Double SR 3 277.778 0.001
Respiration rate at 20C Respiration rate at 20°C ben_resp_rate_20 Double PDR 3 0.02
Respiration Q10 Q10 value for respiration of benthic algae ben_resp_q10 Double 3 2.2 0.001
Mortality rate Mortality rate constant for benthic algae ben_mort_rate Double 3 0.2

Macrophyte parameters

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit
Nitrate uptake (half saturation) Half saturation constant for nitrate uptake mac_n_uptake_half_sat Double PC 3 0.1 0
Phosphate uptake (half saturation) Half saturation constant for phosphate uptake mac_p_uptake_half_sat Double PC 3 0.014 0
Silicate uptake (half saturation) Half saturation constant for silicate uptake mac_s_uptake_half_sat Double PC 3 0.0 0
Nitrogen to carbon ratio Nitrogen to carbon ratio mac_n_c_ratio Double 3 0.16 0
Phosphorus to carbon ratio Phosphorus to carbon ratio mac_p_c_ratio Double 3 0.024 0
Silicate to carbon ratio Silicate to carbon ratio mac_s_c_ratio Double 3 0.0 0
Solar radiation (maximum productivity) Solar radiation required for maximum productivity

mac_pmax_solar_rad

Double SR 3 277.778 0.001
Productivity rate at 20C Productivity rate at 20°C mac_prod_rate_20 Double PDR 3 0.5
Growth Q10 Q10 value for macrophyte growth mac_growth_q10 Double 3 2.2 0.001
Loss by leaching Proportion of dead material that is lost by leaching of nutrients mac_loss_leach Double 3 0.1 0 1
Loss by exudation Proportion of macrophyte production that is lost by exudation of nutrients mac_loss_exude Double 3 0.1 0 1
Seed concentration Seed concentration mac_seed_conc Double WQ_MPA 3 0.0 0
Mortality rate Mortality rate constant for macrophytes mac_mort_rate Double PDR 3 0.05

Hydrogen sulphide parameters

Field Name Help Text Database Field Data Type Size Units Precision Default Error Lower Limit Error Upper Limit Warning Lower Limit Warning Upper Limit
Sulphide flux free flow (M') Sulphide flux coefficient for pipe flowing less than full h2s_free_flow Double RE 5 0.00032 0
Sulphide flux full flow (M) Sulphide flux coefficient for filled pipe h2s_full_flow Double RE 5 0.001 0
Sulphide loss coefficient (m) Coefficient to account for sulphide losses by oxidation and escape to atomsphere. h2s_sulph_loss Double 3 0.64 0
Ionisation coefficient (pK1)

Coefficient determining the relative proportions of H2S and HS- dependent on pH.

A pH value pK1 results in 50% of total sulphides being H2S.

h2s_ion_coeff Double 3 7.0 6.67 7.24
Soluble sulphide percentage Percentage of sulphides that are soluble. h2s_sol_sulph Double 3 80.0 0 100
Parent topic: Water Quality Simulations (InfoWorks)

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