Probe for Windows: Scheduling
- Cyclic (flood): Water applied when the active root Zone water content (RZ1) falls to stress.
- Continous (drip): The Active Root Zone water content (RZ1) is maintained at a Target
- The amount of water that needs to be delivered in next 7 days to reach the Target
- The Target is (normally) the average of UPPER and LOWER limits.
- Schedule amount = (Target - Current + CDWU - Rain ) * Delivery Factor
- See Crop Daily Water Use, predicted rain and Deliver factor for details
- The calculations are done each day.
- If 'chop to full' ON, any rain that takes RZ1 above FULL is assumed to be wasted, and RZ1 will be set to FULL
- The amount can be restricted by the Maximum Pumping Rate
Crop Daily Water Use
Crop Daily Water Use (CDWU), or Soil Water Depletion Rate, can be calculated from one of...
- Probe
Rate-of-change of measured soil moisture. CDWU = Probe DWU
- Estimated
Calculated from the site formula when readings are posted, but the user can chnage the value.
If the value has been changed, this value will be used CDWU = EstimatedDWU
If the value has not been changed, the formula will be re-calculated each day CDWU = SiteFormula * CropFactor * SoilFactor
- Historical
Calculated each day using the site formula. CDWU = SiteFormula * CropFactor * Soilfactor
- Crop
Calculated each day using the crop formula. CDWU = CropFormula * CropFactor * SoilFactor
- Keydata
Calculated each day from a keydata row formula. CDWU = KeydataFormula * CropFactor * SoilFactor
- Forecast
ET from a forecast weather service, or other weather data. CDWU = Forecast ET * CropFactor * SoilFactor
For the remainder of the season (after the next irrigation), CDWU is calculated from...
- Probe, Estimated, Forecast: CDWU = SiteFormula * CropFactor * SoilFactor
- Historical, Crop, Keydata: same formula
Current State
- Summary of current state of the site
- Upper and Lower limits see dwu files (site-specific)
- Check formula - allows formulas to be checked
- <Output> exports Upper/Lower/ET values to csv files for checking
Gains
- Total of all irrigations and rainfalls in the season
- Depth (mm) and Volume (Kl)
- Proportion applied by rain v irrigation
- Efficiency (delivered/applied) of irrigations and rainfall
Delivery
- Continous/drip
- Row spacing etc
- Max delivery hours per day - will limit schedule amount
- Calculates volume from mm
- Cyclic/flood
- Delivered Volume
- Position
- Area of the site allows volumes to be calculated
- Delivery factor - allows for discrepancies between calculated amounts and the amount required for this site
- Delivery rates are calculated from area and delivery rate.
Historical DWU
- Global formula and value (global)
- Site Formula and value (site-specific)
- Calculated and posted to EstDWU as readings uploaded and posted.
- Can also be used to schedule irrigations
- The global formula will be used if there is no site formula
Options
- Available water expressed as % between stress and full - shown on graph. (global)
- Crop type (site-specific)
- Annual - stress = lower (varying)
- Permanent - stress = refill (constant)
- Target-on-top - target shading is more important that stress shading
Mode Options
- Mode - see above (site-specific)
- Crop factor - a value (default=1), values in a
.kc file, or a formula used to calculate Crop Daily Water Use (site-specific)
- Chop gains to full point - RZ1 noter allowed above full point (site-specific)
- Schedule amounts below 5mm are can be set to zero (global)
Scheduling Options
- ProbeDWU - Handle problems if being used to schedule irrigations.(global)
- If a keydata DWU formula is being used to schedule, the key data row needs to be selected (site-specific)
- Weather (site-specific)
- Soil Factor (site-specific)
- Schedule can be shown up to the end of season (local)
- The calculated Schedule Amount can be saved as a key data item, so that the relationship between scheduled, delivered and effective can be graphed and assessed. (site)
- Editing needs to be enabled before values can be changed (local)
Local settings are saved on the PC, and can be different for each PC on a network
Global settings are saved in the shared\ folder, and will be the same for every PC
Sites settings are saved with the site (although could be global)
All below here being edited...
Prediction calculations also use..
- Predicted rain: use (site-sepecific)
- Chop gains to Full point (site-sepecific)
Prediction Variables available for reports here
Amount of water that should be applied
- Cyclic
- Continuous
- Amount required to reach target, total mm in 7 days
- Target-Current + CDWU
- Limited by max pumping rate
Crop water use (DWU) = Evaluate(SiteDWUFormua) * K-Soil Correction
ET/DWU formulas
- Allows for variation as a function of date - dwu details
- Can also include both ET and canopy terms e.g. blenheim.et * shiraz.ca
- Can also be a function of soil moisture status relative to full/refill/pwp (but see k-Soil below).
K Soil Correction
Adjusts DWU depending on the current value of RZ1 relative to FULL and REFILL.
1 = FULL; 0 = REFILL; -0.1 = 10% of (FULL - REFILL) below refill.
Adjustment factor and constant assumed to be dependant on soil type, so the correction factors are saved in a 'KS' file.
e.g. the file SAND.KS (below)
------------------------
Relative, Factor, Constant
1.0, 3.0, 0
0.0, 1.0, 0
-0.1, 0.8, 0
-0.2, 0.0, 1
------------------------
Will adjust the value of dwu depending on the value of soil moisture relative to FULL and REFILL...
| RZ1 below.. | and above.. | Corrected DWU |
|---|
| FULL | DWU = 3*DWU (through-drainage) |
| FULL | REFILL | DWU = DWU (normal) |
| REFILL | 10% below REFILL | DWU = 0.8 * DWU (some stress) |
| 10% below REFILL | 20% below REFILL | DWU = 1 mm/day (high stress) |
The .ks file can also be used to allow for through-drainage when RZ1 is above FULL.
Lower and Upper limits
The Upper and Lower limits are the required maximum and minimum values of RZ1.
- Allow for varying upper and lower limits to be entered as a function of date.
- Values can be specified in either...
absolute mm relative to FULL or REFILL
or relative to FULL and REFILL (or PWP).
Rain
Predicted rainfall scenarios can be used.
GD Note: 'Scenarios' saved in PRWIN2.INI; rainfall data in 'RA' or weather file.
- Rainfalls 'senarios' are in files, with date and amount in mm.
- Actual weather station output files can be used.
- A 'Low' scenario could be generated by analysing rainfall records for the area, over many seasons, and selecting (or generating) a 'low probability' year.
- A 'minimum' amount can be specified.
- Predictions for different rainfall scenarios are saved separately in table 'SCHEDULE'.
Total amounts required for whole season
The effective amount required at each irrigation is calculated as above
Totals for the season are calculated and saved in table SCHEDULE
The required delivered amount = EffectiveAmount * FACTOR4 (to allow for losses in system)
Total volume required (kl) is calculated from TotalDelivered * Wet Area
Wet Area = Area * ( RowSpace / WetWidth )
The calculated crop water use, corrected for K-Soil, is totalled and saved.
Fields in table SCHEDULE - available for GPT, SPT or RPT formulas.
| Field | Description |
|---|
| SeasonID | Identifier for season (join to YEARS.ID) |
| SiteID | Identifier for site (join to SITES.SITE) |
| RainScenarioID | Identifier for rainfall scenario. |
| SEFFIRRI | Total mm that will be effective. |
| SDELIVIRRI | Total mm required to be delivered. |
| SNUMIRRIS | Total number of irrigations. |
| STOTALVOLUME | Total volume required in Kl (mm * WetArea). |
| SEFFRAIN | Total effective rain (delivered less wastage from over full point) |
| SDELIVRAIN | Total rain from scenario (less amounts below lower limit) |
| SNUMRAINS | Total number of rainfalls used in scenario. |
| STOTALDWU | Cumulative total crop daily water use. |
MS Access can be used to generate summary reports across all farms in a region
Details about each individual gain (irrigation) is saved in table SCHDETAIL.
These fields are not available in Prwin, but can be used in Access to re-create the season simulation.
| Field | Description |
|---|
| SeasonID | Identifier for season. |
| SiteID | Identifier for site. |
| RainScenarioID | Identifier for rainfall scenario. |
| DATE | Date of gain |
| GAINTYPE | 2=Irrigation' 3=Rain; 4= EndOfDripPeriod; 15=EndofSeason |
| EffectiveAmount | Effective gain (mm) |
| DeliverAmount | Amount that should be delivered (mm) |
| UpperAmount | Calculated value of Upper formula |
| LowerAmount | Calculated value of Lower formula |
| DWU | Calculated value of crop water use |
| KS | KSoil correction factor used |
| LowestRZ1 | Value of RZ1 just before the gain |
| HighestRZ1 | Value of RZ1 just after the gain |
Predicting next irrigation
The next irrigation is calculated with various options
RDI Factor
Only used to correct the DWU used to predict the next irrigation, but not subsequent irrigations.
e.g. Amount required = DWU * Evaluate(RDIFactor) * 7.
Drip: Calculation of Schedule Amount and Date
The schedule amount is the volume of water required to reach a target soil moisture in 7 days time
The target soil moisture can be either tab: 'mode options'
- do nothing
- target = middle of Upper and Lower
- below lower: target= lower
above upper: target= upper
between lower and upper: do nothing
soil moisture depletion rate, or daily water use
sm = crop et * crop.kc * soil.ks
Crop et (tab: scheduling options)
- PDWU - use the actual, measured, rate of soil mositure depletion
but if too low or too high can revert to a formula
if calculating the rest of the season, use either EstDWU, or Historical DWU
- EstDWU - the value from the site 'historical formula', but the value can be changed by the user
- Historical - the value from the site formula, but the value can not be chaged by the user
- Crop - the value from a formula for the Crop - the value can not be changed by the user
- Keydata - the value from a formula entered in a keydata row
- Forecast - the average forecast et over the next 7 days - see Forecast
amount required = rise/fall to target, less predicted rain
AmountRequired = Target - Current - ForecastRain
application rate will be soil depletion rate - amountrequired/day
rate need to apply water
ApplicationRate = DecisionDWU + (AmountRequired) / (7 days)
If ApplicationRate < 0 Then
too wet ! DWU too low to dry out soil to reach target !
have to fall at dwu only, with zero delivered
ApplicationRate = 0
If ApplicationRate > MaxApplicationRate
pump cannot deliver
ApplicationRate = MaxApplicationRate
if 'chop to full' ON, the soil moisture will not be allowed to go above the full point (fiekld capacity)
any additional water will be assumed to be lost to through-drainage or surface runoff
calculate the rate RZ1 needs to fall/rise to hit target
if in manual mode, 'fd_ScheduleAmount' is how much *will* be applied
this needs reducing by factor2 to get 'effective gain in soil'
AmountRequired = (ScheduleAmount / Factor2) - ForecastRain
Final...
.EffectiveAmount = RequiredAmount
.DeliverAmount = RequiredAmount * Factor2
if DeliverAmount < Reasonable
DeliverAmount = 0
---
ReadingsMenu/Scheduling
Check: Show Untill !!!
global settings saved in shared\prwin2.ini
OutputNegativeAsZero, and value
flood: schedule date= 'today'
% available mode FUll/REFILL, FULL/PWP
local settings saved in App.Path\prwin2.ini
plot lines on graph checkboxes
dateFormat default= "h:mm d mmm yyyy")
'days ahead for plotting graph
default=10
allow editing
saved in Site
Upper, Lower limits