Flow in drainage systems frequently exceeds the sum of stormwater runoff and domestic and trade inflows. This residual flow is usually attributed to infiltration, which enters the system through cracks. Unlike runoff, which responds to a rainfall event in minutes, infiltration inflows have a much slower response. There are two main types of infiltration:
- Rainfall-induced infiltration results from soil water infiltrating directly into the network. This has an effect on flow within hours or days of the storm.
- A proportion of rainfall percolates deeper into the groundwater reservoir and in the weeks or months following the storm the groundwater level may be sufficiently high to cause groundwater infiltration.
The Ground Infiltration object defines the fixed groundwater characteristics of the subcatchment.
This table describes all the data fields used to define a Ground Infiltration object.
Fields that are common to the majority of objects can be found in the Common Fields topic.
Ground Infiltration Data
Database Table Name: hw_ground_infiltration
|
Field Name |
Description |
Database Field |
Size |
Precision |
Default |
Error Lower Limit |
Error Upper Limit |
Warning Lower Limit |
Warning Upper Limit |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Ground infiltration ID |
A unique identifier for the ground infiltration record. This field is used to associate a Ground Infiltration ID with a particular subcatchment. |
ground_id |
Text |
64 |
|
0 |
|
|
|
|
|
||||||
|
Soil depth |
An estimate of the soil depth. |
soil_depth |
Double |
|
Y |
3 |
10.0 |
0 |
|
|
|
||||||
|
Percolation coefficient |
A time coefficient, determined by calibration from existing data. It is recommended that the value should be between 0.1 and 10 |
percolation_coefficient |
Double |
|
TD |
3 |
1.0 |
0 |
|
|
|
||||||
|
Baseflow coefficient |
A time coefficient, determined by calibration from existing data. It is recommended that the value should be between 100 and 10000 |
baseflow_coefficient |
Double |
|
TD |
3 |
1.0 |
0 |
|
|
|
||||||
|
Infiltration coefficient |
A time coefficient, determined by calibration from existing data. It is recommended that the value should be between 0.1 and 10 |
infiltration_coefficient |
Double |
|
TD |
3 |
1.0 |
0 |
|
|
|
||||||
|
Percolation threshold |
The percentage saturation level of the soil at which water starts to percolate downwards |
percolation_threshold |
Double |
|
|
3 |
50.0 |
0 |
|
|
|
||||||
|
Percolation percentage infiltrating |
The percentage of percolation flow that infiltrates directly into the drainage network. |
percolation_percentage |
Double |
|
|
3 |
5.0 |
0 |
100 |
|
|
||||||
|
Porosity of soil |
A coefficient representing the porosity of the soil (upper storage reservoir) |
soil_porosity |
Double |
|
|
3 |
50.0 |
0 |
100 |
|
|
||||||
|
Porosity of ground |
A coefficient representing the porosity of the ground (lower storage reservoir) |
ground_porosity |
Double |
|
|
3 |
50.0 |
0 |
|
|
|
||||||
|
Baseflow threshold level |
The groundwater level at which secondary infiltration occurs. |
baseflow_threshold |
Double |
|
Y |
3 |
|
|
|
|
|
||||||
|
Baseflow threshold type |
The Baseflow Threshold Level can be either an absolute value (relative to Model Datum) or a level relative to the chamber floor of the node to which the subcatchment drains.
|
baseflow_threshold_type |
Text |
8 |
|
0 |
Relative |
|
|
|
|
||||||
|
Infiltration Threshold Level |
The level of the groundwater storage reservoir at which groundwater infiltration occurs. It is recommended that the Infiltration Threshold Level should be between 0 and 5 m above the Baseflow Threshold. |
infiltration_threshold |
Double |
|
Y |
3 |
|
|
|
|
|
||||||
|
Infiltration threshold type |
The Infiltration Threshold Level can be either an absolute value (relative to Model Datum) or a level relative to the chamber floor of the node to which the subcatchment drains.
|
infiltration_threshold_type |
Text |
8 |
|
0 |
Relative |
|
|
|
|
||||||
| Evapotranspiration type |
The type of evapotranspiration can be set to either:
|
evapotranspiration_type |
Text |
|
|
8 |
Linear |
|
|
|
|
||||||
| Evapotranspiration depth |
The depth where evapotranspiration stops. |
evapotranspiration_depth |
Double |
|
Y |
3 |
|
0 |
|
|
|
||||||
| Jan evapotranspiration factor | The evapotranspiration factor applied to January. | evapotranspiration_fac_Jan |
Double |
|
|
3 |
1.0 |
0 |
1 |
|
|
||||||
| Feb evapotranspiration factor | The evapotranspiration factor applied to February. | evapotranspiration_fac_Feb |
Double |
|
|
3 |
1.0 |
0 |
1 |
|
|
||||||
| Mar evapotranspiration factor | The evapotranspiration factor applied to March. | evapotranspiration_fac_Mar |
Double |
|
|
3 |
1.0 |
0 |
1 |
|
|
||||||
| Apr evapotranspiration factor | The evapotranspiration factor applied to April. | evapotranspiration_fac_Apr |
Double |
|
|
3 |
1.0 |
0 |
1 |
|
|
||||||
| May evapotranspiration factor | The evapotranspiration factor applied to May. | evapotranspiration_fac_May |
Double |
|
|
3 |
1.0 |
0 |
1 |
|
|
||||||
| Jun evapotranspiration factor | The evapotranspiration factor applied to June. | evapotranspiration_fac_Jun |
Double |
|
|
3 |
1.0 |
0 |
1 |
|
|
||||||
| Jul evapotranspiration factor | The evapotranspiration factor applied to July. | evapotranspiration_fac_Jul |
Double |
|
|
3 |
1.0 |
0 |
1 |
|
|
||||||
| Aug evapotranspiration factor | The evapotranspiration factor applied to August. | evapotranspiration_fac_Aug |
Double |
|
|
3 |
1.0 |
0 |
1 |
|
|
||||||
| Sep evapotranspiration factor | The evapotranspiration factor applied to Septemeber. | evapotranspiration_fac_Sep |
Double |
|
|
3 |
1.0 |
0 |
1 |
|
|
||||||
| Oct evapotranspiration factor | The evapotranspiration factor applied to October. | evapotranspiration_fac_Oct |
Double |
|
|
3 |
1.0 |
0 |
1 |
|
|
||||||
| Nov evapotranspiration factor | The evapotranspiration factor applied to November. | evapotranspiration_fac_Nov |
Double |
|
|
3 |
1.0 |
0 |
1 |
|
|
||||||
| Dec evapotranspiration factor | The evapotranspiration factor applied to December. | evapotranspiration_fac_Dec |
Double |
|
|
3 |
1.0 |
0 |
1 |
|
|