Transcript Document

WASAMED
International Conference on
Water Saving in Mediterranean Agriculture & Future
Research Needs
14-17 February 2007, Bari, Italy
ASSESSING THE SIMDualKc MODEL FOR
IRRIGATION SCHEDULING SIMULATION
IN MEDITERRANEAN ENVIRONMENTS
J. Rolim, P. Godinho, B. Sequeira, Paula Paredes, L. S. Pereira
Agricultural Engineering Research Center, ISA, UTL, Tapada da Ajuda,
1349-017 Lisbon, Portugal, [email protected]
WASAMED
Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
1. Introduction
2. The dual crop coefficient approach
3. SIMDualKc Model structure
4. Model validation
5. Results and discussion
6. Conclusions
WASAMED
Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
1. Introduction
SIMDualKc is a
software tool to
simulate the soil water
balance by computing
ETc and perform soil
water balance
simulation based on
the dual crop
coefficient (Kcb + Ke)
approach.
ETc = (Kcb + Ke) ETo
WASAMED
Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
Model main goals:
• computing crop water requirements and irrigation scheduling,
mainly focusing vegetables and orchard crops, partial cover
crops, mulched soil, high frequency irrigation;
• improve accuracy in irrigation programming;
• making available an accurate and easy to use simulation tool;
• advising irrigators.
SIMDualKc model applies:
• at field level;
• with daily time step;
• to real-time irrigation scheduling when meteorological
data is available, assessing the evolution of the soil water
content
WASAMED
Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
2. Dual crop coefficient approach
The dual Kc approach
(Kcb + Ke) shall
produce more
accurate ETc
estimates for regions
with frequent rainfall,
in high frequency
irrigations, and
partial cover crops.
Partitioning Kc into Ke and Kcb components allows better
following the impacts of wetting the soil by rain or irrigation, as
well as the impacts of keeping part of the soil dry, or using
mulches for controlling soil evaporation.
WASAMED
Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
3. Model structure
The model was developed using a three tiers architecture approach:
database, mathematical model and a graphic user interface (GUI)
Mathematical model
Data Base
Modules:
- Soil
- Climate
- Crop
- Simulations
- Kcb computation
- Kcb adjustment
- Ke computation
- ETc computation
- Soil water balance
Graphical User Interface
Dialog structure
Results
WASAMED
Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
SIMDualKc flowchart
Start
GUI
Yes
No
Stand alone?
Inputs
Abstract
Interface
WINISAREG
Outputs
Abstract
Interface
SIMDualKc
Model
Yes
Yes
No
Stand alone?
GIS?
No
SIMDualKc
Data base
WINISAREG
Data base
HidroGest
Data base
Two abstract interfaces are
used:
 one to link the
computational module
with the GUI or with the
selected model;
 other to connect the
numerical modules to
the database, through
queries that enable to
adapt different
databases to the data
structure of SIMDualKc
including GIS;
WASAMED
Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
SIMDualKc core
algorithm &
methodology (FAO56)
Start
INPUT DATA
Soil; Climate; Crop; Irrigation
Computation of daily Kcb adjusted
Calculation of Kc max
Daily calculation:
fc; fw; few
Daily calculation:
Kr; Ke; Ks
Daily calculation:
E; Kc; ETc
Daily calculation of:
Kc act; Soil water deplection (mm)
End
WASAMED
Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
Main Menu
Soil data menu
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Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
Crop menu
Meteorological data
menu
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Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
Model inputs
climate
+ crop
+ soil
Field representation
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Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
Model
outputs
Kc and
depletion
curves
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Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
Model
outputs
Export table
of results
WASAMED
Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
Model validation
SIMDualKc validation was performed:
 using field and meteorological data collected in various
experimental fields;
 by comparing observed and simulated soil water
content values using a regression through the origin.
 Mediterranean basin
 Portugal (Maize)
 Tunisia (Winter wheat)
 Syria (Winter wheat)
 Italy (Citrus)
 Central Asia (cotton)
Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
WASAMED
TAW
350
300
3 basin irrigation events
250
300
200
OYT
150
100
50
0
159
174
189
204 219
julian day
234
249
y = 0.992x
2
R = 0.900
250
Simulated ASW (mm)
ASW (mm)
Results – Portugal (Maize)
200
150
100
50
0
0
50
100
150
200
250
Observed ASW (mm)
300
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Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
350
2 basin irrigation
events
300
250
300
200
y = 1.0185x
R 2 = 0.847
150
100
50
0
159
174
189
204
219
julian day
234
249
Simulated ASW (mm)
ASW (mm)
Results – Portugal (Maize)
250
200
150
150
200
250
Observed ASW (mm)
300
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Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
300
250
200
200
150
160
100
50
0
320 340 360 14 34 54 74 94 114 134 154 174
julian day
Simulated ASW (mm)
ASW (mm)
Results – Tunisia (Winter wheat)
y = 0.9971x
2
R = 0.9423
120
80
40
0
Supplemental irrigation with
furrow irrigation
0
40
80
120
160
Observed ASW (mm)
200
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Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
140
120
Sprinkler irrigated
100
120
y = 0.9973x
R2 = 0.8243
80
100
60
40
20
0
319 339 359 14
34
54
74
julian day
94 114 134 154
Simulated ASW (mm)
ASW (mm)
Results – Syria (Winter wheat)
80
60
40
20
0
0
20
40
60
80 100
Observed ASW (mm)
120
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Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
180
150
120
120
90
100
60
30
0
305 325 345 365
20
40
60
julian day
80
100 120 140
Simulated ASW (mm)
ASW (mm)
Results – Syria (Winter wheat)
y = 0.9784x
R2 = 0.8658
80
60
40
20
0
Sprinkler irrigated
0
20
40
60
80
Observed ASW (mm)
100
120
WASAMED
Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
140
120
100
140
80
Simulated ASW (mm)
ASW (mm)
Results – Italy (Citrus)
60
40
20
0
150
170
190
210
230
250
270
julian day
290
310
y = 0.9597x
2
R = 0.7533
120
100
80
60
40
20
0
0
Microsprinkler irrigation
20
40
60
80
100
Observed ASW(mm)
120
140
WASAMED
Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
150
100
150
y = 0.9836x
R2 = 0.9312
50
0
96
126
156
186
Julian day
Furrow irrigation
216
246
Simulated ASW (mm)
ASW (mm)
Results – Central Asia (Cotton)
100
50
50
100
Observed ASW (mm)
150
WASAMED
Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
Summary of Results
Crop experiment
Irrigation
method
Regression
coefficient
Determination
coefficient
Maize, Portugal, 3 irrigations
Level basin
irrigation
0.99
0.90
Maize, Portugal, 2 irrigations
Level basin
irrigation
1.02
0.85
Wheat, Tunisia
Furrow irrigation
1.00
0.94
Wheat, Syria, first year
Sprinkler
1.00
0.82
Wheat, Syria, second year
Sprinkler
0.98
0.87
Citrus, Italy
Microsprinkler
0.96
0.75
Cotton, Central Asia
Furrow irrigation
0.98
0.93
WASAMED
Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
Conclusions
1. The SIMDualKc validation show good adherence of model
results to field observations;
2. The model accurately follows the evolution of soil
moisture along the crop season:
• proves to be particularly satisfactory in the simulation of soil
water balance during initial stages of development;
• this indicates that computing ETc with the dual approach is
highly accurate;
WASAMED
Assessing the SIMDualKc Model for Irrigation Scheduling
Simulation in Mediterranean Environments
Conclusions
3. The model shows to be able to support farmers’ advice
as well as to predict ET and irrigation requirements for
planning and environmental studies;
4. The model presents high capability to simulate the soil
evaporation component and constitutes an important
support for irrigation and soil management.
WASAMED
International Conference on
Water Saving in Mediterranean Agriculture &
Future Research Needs
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