PDM Descriptor Data Fields
Simulations using PDM functionality can only be run if the PDM option is enabled on your licence.
PDM Descriptor data can be edited on either the PDM Descriptor Grid Window of the Subcatchments Grid or the PDM Descriptor Property Sheet.
This table describes all the data fields used to define a PDM Descriptor object.
Common Data Fields Fields that are common to the majority of objects can be found in the Common Fields topic.
PDM Descriptor Data
Database Table Name: hw_pdm_descriptor
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Field Name |
Help Text |
Database Field |
Size |
Precision |
Default |
Error Lower Limit |
Error Upper Limit |
Warning Lower Limit |
Warning Upper Limit |
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| Descriptor ID | Name of the PDM Descriptor object. | descriptor_id | Text | 64 | 0 | ||||||||||||||||||||||||
| Rainfall and evaporation |
Method used to calculate rainfall and evaporation:
|
re_type | Text | 50 | 0 | Standard | 0 | 0 |
0 |
0 |
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| Rainfall factor | Multiplying factor to be applied to measured rainfall to obtain an average rainfall across the catchment. | rainfac | Double | 3 | 1 | 0 |
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| Evaporation exponent | Exponent in evaporation function. | be | Double | 3 | 2.5 | 0 |
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| Infiltration rate parameter | Enabled when Rainfall and evaporation set to Infiltration or Infilt_frozen | kinf | Double | I | 3 | 0 | 0 | ||||||||||||||||||||||
| Frozen infiltration rate parameter | Enabled when Rainfall and evaporation set to Infilt_frozen | kfreeze | Double | 3 | 0 | 0 | |||||||||||||||||||||||
| Frozen time constant | Enabled when Rainfall and evaporation set to Infilt_frozen | kt | Double | 3 | 0.5 | 0 | |||||||||||||||||||||||
| Soil moisture distribution |
Method used to calculate soil moisture distribution:
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smd_type | Text | 50 | 0 | Pareto | 0 | 0 |
0 |
0 |
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| Minimum storage capacity | Minimum storage capacity in the catchment. | cmin | Double | SC | 3 | 1.5 | 0 |
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| Maximum storage capacity | Maximum storage capacity in the catchment. | cmax | Double | SC | 3 | 75 | 0 |
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| Pareto exponent |
Exponent of Pareto distribution controlling spatial variability of store capacity. Enabled when Soil moisture distribution is set to Power. |
b | Double | 3 | 1 | 0 | |||||||||||||||||||||||
| Recharge/runoff |
Method used to calculate recharge and runoff:
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rr_type | Text | 50 | 0 | Standard | 0 | 0 |
0 |
0 |
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| Ground recharge time constant |
Groundwater recharge time constant. Enabled when Recharge/runoff set to Standard. |
kg | Double | 3 | 1000 | 0 |
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| Soil tension storage capacity |
Threshold storage below which there is no drainage; water being held under soil tension. Enabled when Recharge/runoff set to Standard. |
St | Double | SC | 3 | 0 | 0 |
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| Recharge function exponent |
Exponent of recharge function. Enabled when Recharge/runoff set to Standard. |
bg | Double | 3 | 1 | 0 |
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| Initial soil moisture proportion of max | Enabled when Recharge/runoff set to Splitting or Split_unrest. | theta | Double | 3 | 0.7 | ||||||||||||||||||||||||
| Surface flow runoff proportion |
Runoff factor controlling the split of rainfall to surface and groundwater storage routing when no soil recharge is allowed. Enabled when Recharge/runoff set to Splitting or Split_unrest. |
alpha | Double | 3 | 0.4 | 0 | 1 (Splitting only) | ||||||||||||||||||||||
| Baseflow store runoff proportion |
Proportion of runoff entering the baseflow store. Enabled when Recharge/runoff set to Split_unrest. |
beta | Double | 3 | 0 | ||||||||||||||||||||||||
| Groundwater deficit ratio threshold | Enabled when Recharge/runoff set to Demand_based. | alpha_d | Double | 3 | 0.5 | 0 | |||||||||||||||||||||||
| Maximum recharge rate | Enabled when Recharge/runoff set to Demand_based. | qsat_d | Double | I | 3 | 2 | 0 | ||||||||||||||||||||||
| Groundwater demand factor exponent | Enabled when Recharge/runoff set to Demand_based | beta_d | Double | 3 | 1 | ||||||||||||||||||||||||
| Surface store |
Method used to calculate surface storage:
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ss_type | Text | 50 | Linear_cascade | 0 | 0 |
0 |
0 |
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| Linear reservoir 1 time constant | Linear reservoir time constant | k1 | Double | 3 | 10 |
0.00025 (Linear cascade) 0 (surface storage except linear cascade) |
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| Linear reservoir 2 time constant | Enabled when Surface store set to Linear_cascade | k2 | Double | 3 | 0 | 0.005 |
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| Interflow |
Method used to calculate interflow (lateral flow through soil layers). If Interflow is set to a value other than None, Recharge and runoff must be set to Standard and Soil moisture deficit must be set to Pareto.
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if_type | Text | 50 | 0 | None | 0 | 0 |
0 |
0 |
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| Interflow time constant |
Enabled when Interflow set to choice other than None. |
ki | Double | 30 | 3 | 30 | 0 | ||||||||||||||||||||||
| Interflow factor | Enabled when Interflow set to choice other than None | fi | Double | 3 | 0 | 0 | 1 | ||||||||||||||||||||||
| Baseflow store |
Method used to calculate baseflow
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bs_type | Text | 50 | 0 | Cubic | 0 | 0 |
0 |
0 |
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| Baseflow time constant |
Constant used for all baseflow modelling methods. The metric unit used for the baseflow time constant is: h mm^(M-1), where M is the exponent in the baseflow storage equation |
kb | Double | 3 | 500 | 0 |
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| Time delay | Constant time delay applied to output flow | tdly | Double | 3 | 0 | 0 |
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