for assistance with the model please contact: prof. …...information on data availabilty on rhmin...
TRANSCRIPT
For assistance with the model please contact: Prof. Luis S Pereira ([email protected]) or Dr. Paula Paredes ([email protected])
First, all mandatory input data are filled
Then optional input data are filled
Finally combine data is created
2. Select the type of soil data used to compute TAW
When necessary, use data/information stored on typical
values
1. Type a soil name
1. SOIL
When using new data click Newwhen modifying data click EditAfter handling data click Save(or Delete all data and re-start)
Always move out with CloseClick < or > to find the file you want
TAW indicative information
Soil water content at saturation, field capacity, wilting point and TAW
Bulk density and pore spacing
1. SOIL
4. Fill in the information for each layer
3. Select the number of soil layers
When soil data is complete move to evaporable soil layer
1. SOIL
1. Select the type of soil data used to compute TEW and REW
When necessary, use data/information stored on typical
values
2. Fill in the information for each layer
3. Save the file
Percentage of clay, silt and sand for main textural classes
TEW from textural classes for commonly used evaporation layer thicknesses (Ze)
REW from textural classes
1. Click here to create a climate file
CLIMATIC DATA
Search stored files
1. Choose an option relative to the introduction of ETo and precipitation data
2. Select data to be inputed
2. Select data to be inputed
3. Information on data availabilty on RHmin and windspeed for Kcb correction for climate
4. Create excel file with all meteo data
The model generates a excel file to input all data identified in the previous window
The first 2 lines cannot be changed because they refer to codes
Example of excel file to be read by the model. This example refer to a case where ETo was already computed and input includes Tmax and Tmin and wind speed to correct Kcb for climate
Example of excel file to be read by the model. This example refer to a case where ETo is to be computed by the model
Always daily data is to be pasted with columns referring to the variables as selected by the model when it generates the file
These excel data files are saved with the name of the weather station as “.txt” (text tab delimited)
IMPORTANT NOTES1. Climatic data files have to always start by the 1st
January and end by 31st December. 2. When data is available for a period shorter than the
year, all days from 1st January to the first day with data and from last day until 31 December need to be filled with 0
3. A file may comprise various years of data but every year has to be filled in full as per above
4. After introducing all data in the excel file the latter is saved save as “.txt” (text tab delimited)”. Close it and re-open to clean the file, which is performed by deleting 5 or more columns at the right and some rows at the bottom. Then check if there are columns or lines with blanks; if so clean again. Last, save again.
A window to create a new weather station shows up . Thus click New station
When the txt file is created click New
2. Fill in the base data relative to the station1. Name the new station
3. Click Next to import data from the txt file to the model
4. In this window
select File path
5. A window shows up asking to select the txt file relative to the new
station. Click OK
6. Select the txt file
and open it
7. Validate your climatic data file, i.e., the model verifies if there are data lacking or it the cleaning of the txt file was not proper
9. Only in case that ETo is computed with estimated Rs, RH and/or wind speed than provide related parameters
8. When the file is validated click OK
10. Click to import weather data
11. Save
Weather data are now available in graphic and table format . Choose data and year
2. Name the new crop3. Choose type of crop
a. b. c.
4.
4.a.
When necessary, use data/information stored on typical
values
CROP CHARACTERIZATION
1. Change an existing crop file or create a new
Indicative lengths of crop development stages
Crop height, maximum root depths and depletion fractions for no stress
To compute the impacts on soil evaporation of soil covered by the crop it is necessary to input the fraction of ground covered by the crop or alternatively the LAI data at specific dates or at the crop growth stages
4.b.
1 2 3
Example of fc for wheat
Measuring LAI in a pea field (randomlysowed)
Measuring LAI in a maize field
Input the Kcb values already taking into account actual crop densityMake appropriated adjustments of Kcb mid and Kcb end to climatic conditions
5.
5.a.
1 2
3
When necessary, use data/information stored on typical
values
Example ofdefault valuesfor basal crop coefficients
Input the Kcb values for full cover conditions
5.b.
5.
1 2
3 4
Information required to adjust Kcb full to crop density
5
1
23
4
Adjustment of Kcb using fc measured at specific dates
5
12
1 2
3
4
Forage crop with multiple cuts
Compute the relative yield losses using the Stewarts water-yield model
1
2
Stewart water-yield approach
The SIMDualKc model allows using the Stweart water-yield
approach to assess the impacts of water stress on yields;
this approach assumes that yield decreases vary linearly
with the evapotranspiration deficits according to a yield
response factor.
c
ay
m
a
ET
ET1K
Y
Y1
Ym maybe observed, estimated from data information collected
from farmers in the study areas, or estimated using the
Wageningen method or by the Agro-ecological zoning (AEZ)
method (Doorenbos and Kassam, 1979; FAO 1996).
𝑌𝑎 = 𝑌𝑚 −𝑌𝑚 𝐾𝑦 𝑇𝑑
𝑇𝑐
An adaptation is to use crop transpiration deficit as the driver for computing yield decreases
IRRIGATION MANAGEMENT
Click < or > to find the file you want
2. Select the irrigation method
1. Type a irrigation option name
3. Select the
fraction of surface wetted by irrigation or input a value if available4. Select the irrigation
timing5. When appropriated
select the limit for the last irrigation
2. When selecting an irrigation methoda default value for the fraction of soil surface wetted by irrigation will appear. This fraction may be changed by the user according to observations
IRRIGATION MANAGEMENT
3. Irrigation timing options: (i) rainfed, (ii) avoid water stress or (iii) deficit irrigation
For ii) and iii) Management allowed depletion thresholds are to be used
Irrigation schedule aiming at avoiding water stress namely during the mid-season which includes flowering and fruits development
Usually crops are not irrigated after reaching maturity. Value depends upon crop management
Moderate stress irrigation Schedule example. Note that during mid-season a very mild deficit is allowed thus, preventing high yield losses
The fixed net irrigation depths depends upon the irrigation method and may be changed along the crop season
IRRIGATION MANAGEMENT
User may select an irrigation depth threshold depending on soil TAW
The model allows evaluating a pre-determined irrigation schedule
1.
2.
When there are water restrictions in terms of amount or periods the model allows integrating that information to simulate an appropriated irrigation schedule
MODEL EXTENSIONS
1.
2.
Precipitation runoff using the curve number approach
CN which depends upon the soil texture and previous cultivated crop
Active ground cover
1.
2.
3.
According to management operations active ground cover condition may be updated along crop season
4.
4a.
4.
4b.
According to management operations active ground cover condition may be updated along crop season
Active ground cover during spring
After herbicide application in late spring
5.
MULCHES
1.
2. 2a.2b.
DEEP PERCOLATION AND CAPILARY RISE
1.
Select one of theoptions for capilary risecomputations
2.
Introduce dates and CR amounts
When necessary, use information stored on typical values
1.
Data from fieldobservations
2.
Capillary risecomputation
DEEP PERCOLATION
aD is the soil water storage value ranging saturation and field capacity bD depends upon the drainability of the soil
1.2.
Soil water contente for 1 m depthrelative to saturation, fieldcapacity and wilting point
DEEP PERCOLATION
INTERCROPPING
1.
2.
3.
4.
Wheat-maize relayintercropping, Hetao, China
Wheat-sunflowerrelay intercropping,
Hetao, China
SOIL AND WATER SALINITY IMPACTS ON CROP TRANSPIRATION
2.
1.
SOIL AND WATER SALINITY IMPACTS ON CROP TRANSPIRATION
2a.
2b.
SOIL AND WATER SALINITY IMPACTS ON CROP TRANSPIRATION
3.
3b.3a.
Crops salinity ECe threshold and b parameter
SOIL AND WATER SALINITY IMPACTS ON CROP TRANSPIRATION
4.
4a.
4b.
SOIL AND WATER SALINITY IMPACTS ON CROP TRANSPIRATION
After creating the appropriated data files you are now ready for combining data and start simulations
Create a new data combination and write a name (do not use a name equal to other in the database)
Select the appropriated file data already created relative to mandatory data
1.
1a.
2.
3.
4.
All other data are optional
5. Save the files combination and
in the following start the simulation
Results are now ready to be explored.
The model shows tabled and graphical presentation of results or user may export the
results selecting ALL RESULTS
Results relative to relative yield losses are only available in the tabled values and not in the txt output file
Results relative to yield decrease
Select a folder to save the txt file
All resultsmay beexported as txt file
The text file may be open in excel and figures may be drawn relative to several model outputs e.g. soil water dynamics, seasonal variation of crop coefficient and evaporation coefficient, seasonal dynamics of available soil water, dynamic of crop transpiration and soil evaporation, …
Kcb adjusted to water stress (Kcb act = Kcb Ks)
Examples of graphicscreated in excel
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27/0
4
04/0
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11/0
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25/0
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08/0
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29/0
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27/0
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31/0
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07/0
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AS
W (
mm
)
TAW
RAW
Simulated and observed available soil waterDynamics, center pivot irrigated maize, Portugal
0
1
2
3
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6
7
8
9
10
27
/…
04
/…
11
/…
18
/…
25
/…
01
/…
08
/…
15
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22
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29
/…
06
/…
13
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20
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27
/…
03
/…
10
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17
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24
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31
/…
07
/…
14
/…
E s, T
c an
d T
cac
t(m
m d
-1)
Crop transpiration and soil evaporationdynamics
0
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80
1000.0
0.2
0.4
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1.0
1.2
1.4
27
/04
04/0
51
1/0
51
8/0
525/0
50
1/0
60
8/0
615/0
62
2/0
62
9/0
606/0
71
3/0
72
0/0
727/0
70
3/0
81
0/0
817/0
82
4/0
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1/0
80
7/0
91
4/0
9
Pre
cip
ita
tio
n,
irri
ga
tio
n (
mm
)
Kc
act
, K
e, K
cb,
Kcb
act
Single Kc, Ke andKcb curves
