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IrrigatorRemainingUsage = Estimateof the total volume of irrigation required to complete crops in the current irrigation season
Assumptions and constraints
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Table 1 — Assumptions and constraints applying to storage flow routing methods
No | Assumption/Constraint |
1 | The crop model has been designed to represent a group of farms and assumes the irrigation behaviour of a group of farms. |
2 | Crops are planted on the same specified date each year of the simulation. |
3 | Crop yield is a linear response to water stress |
Table 1 — Assumptions and constraints applying to storage flow routing methods
| 4 | The areas of crop will be less than or equal to the area of the district |
Parameters/Settings
Data
Refer to the Source User Guide for detailed data requirements and formats.
Input data
The information that users need to provide is summarised in the tables below.required is:
- Daily time series of rainfall
- Daily time series of reference crop evapotranspiration
- Crop factors
- Crop area
Parameters and Settings
District Configuration
| Parameter | Description | Unit | Default | Typical Range | |||||
|---|---|---|---|---|---|---|---|---|---|
Maximum Irrigated Area | Nominal maximum irrigated area. Used in defining the area of fallow. Warning generated if area exceeds this fall | Haha | 0 | 0-500,000 | |||||
Soil Moisture Capacity | The difference in volumetric soil water content between field capacity and permanent wilting point | % | 0 | 10-30 | |||||
Irrigation season start date | The first day on which water can be delivered to irrigators | Calendar date | Irrigation districts – 15 August Private diverters – 1 July | 1/1-31/12 | |||||
Irrigation season end date | The last day on which water can be delivered to irrigators | Calendar date | Irrigation districts – 31 May Private diverters – 30 June |
| 1/1-31/12 |
Climate Configuration
| Parameter | Description | Unit | Default | Typical Range |
|---|---|---|---|---|
Evapotranspiration | Reference crop evapotranspiration, as defined by FAO56. Suggest using SILO data | mm mm/day | 0 | 0-15 |
Average evapo\rationspiration | Average evapotranspiration used for forecasting soil water depletion and demand | mm | 0 | 0-15 |
Rainfall | Rainfall timeseries | mm/day | 0 | 0- |
Average Rainfall | Average rainfall used for forecasting soil water depletion and demand | mm | 0 | 0- |
District Supply Escape
| Parameter | Description | Unit | Default | Typical Range |
|---|---|---|---|---|
Supply Escape Efficiency | The percentage of water supplied to the district that is lost from the supply system | % | 0 | ≥ 0-100 |
Escape Return Efficiency | The percentage of the supply escape that is collected in drainage system and can be recycled | % | 0 | ≥ 0-100 |
District Return Efficiency
Parameter | Description | Unit | Default | Typical Range |
|---|---|---|---|---|
Supply Escape Efficiency | Disabled. The district return efficiency is only applied to return flows | % | 0 | 0-1000 |
Return Effficiency | The amount of all harvested return flows that is passed back to the water user. | % | 0 | ≥ 0 |
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| Parameter | Description | Unit | Default | Typical Range |
|---|---|---|---|---|
Crop | Crop type | - | - | - |
Crop Type | Type of crop being grown – Either Annual or Perennial | - | - | - |
Planting Window | The number of days over which a crop area is planted. This defines the number of uniform size sub-areas for initial watering of cropped area. | days | 1 | 1-30 |
Planting Margin | Defines the time period following planting that the crop will not die as a result of water stress. This prevents crop death if initial planting is delayed. | days | 1 | ≥ 0 |
Crop Soil Configuration
| Parameter | Description | Unit | Default | Typical Range |
|---|---|---|---|---|
Dr- Depth of rootzone | Depth of soil profile that water is extracted for ET. For fallow, this is the depth of soil that soil water will deplete due to evaporation. | mm | 0 | 30-1000 |
p - Depletion Factor | Percentage of total available water that a crop can extract from the root zone without suffering water stress | % | 0 | 50 |
Initial Depletion | Soil water depletion used to initialise a model run | mm | 0 | 0-100 |
Fallow factor | Limit on evaporation from fallow soils. Equivalent of a crop coefficient, but used for fallow. | - | 0 | 0.4-1 |
Crop Planting Decision
| Parameter | Description | Unit | Default | Typical Range | ||
|---|---|---|---|---|---|---|
Decision Type | Allows user to select different methods for specifying the crop area on the planting date. Either a fixed area (which supports expressions and data sources) or a lookup table that relates available water on the planting date to the planted area. |
| Fixed Area |
| ||
Plant Date | Date that the planting decision is made and the crop is planted | Calendar date | 31 May | 1/1-31/12 | ||
Harvest Date | Date crop is harvested. By default this is disabled | Calendar date | n/a | 1/1-31/12 | ||
Under Irrigation Factor | Reduces irrigation application by adjusting the target depletion level. | % | 0 | 0-50 | ||
Area relationship | Defines the crop area as a function of either available water using a lookup table or from an expression or data source |
|
| ML vs ha | Fixed area | 3-14 ML/ha |
Soil Depletion
| Parameter | Description | Unit | Default | Typical Range |
|---|---|---|---|---|
Target Soil depletion | The target soil water depletion that irrigation attempts to maintain. Negative values used for ponded crops | mm | 0 | 150 to 100 |
Opportunistic target soil depletion | Soil water depletion that opportunistic water is used to refill. By default this is disabled. Negative values used for ponded crops | mm | 0 | -150 to 100 |
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| Parameter | Description | Unit | Default | Typical Range |
|---|---|---|---|---|
Start Date | The first day where target levels are modified | Calendar date | 15 March | 1/1-31/12 |
End Date | The last day where target levels are modifed | Calendar date | 30 April | 1/1-31/12 |
Modifier | The amount that crop water use is to be reduced during modifier period. | % | 0 | 0-50 |
Crop Economics - Note: Still Crop Economics functionality is still in prototype stage
| Parameter | Description | Unit | Default | Typical Range | ||
|---|---|---|---|---|---|---|
Yield | Water stress coefficient (Ks) describes the effect of water stress on crop transpiration | % | 0 | 0-100 | ||
Expected Usage | Expected total irrigation requirement for crop for the growing season. This is used to evaluate expected surplus/shortfall of water availability | ML/Hamm | 0 | 5-15 | ||
Gross Margin | Not used and will either be removed or used for other purpose. Could be used to specify maximum yield, thus allowing output of a crop in physical units | Productivity | Multiplier to convert yield into user specified output units | none |
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References
DIPNR (2004), IQQM Reference manual, Version 1.2, NSW Department of Infrastructure Planning and Natural Resources, NSW.
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