Transcript Diapositivo 1 - CIHEAM,Istituto Agronomico Mediterraneo

DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE
WITH CENTER-PIVOT SPRINKLER SYSTEMS
Valín Sanjiao M.I.; Santos Pereira L.
Agricultural Engineering Research Center, Institute of Agronomy, Technical University of Lisbon.
WATER SAVING IN MEDITERRANEAN AGRICULTURE & FUTURE RESEARCH NEEDS
CIHEAM, Mediterranean Agronomic
Institute of Bari, Italy
DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH
CENTER-PIVOT SPRINKLER SYSTEMS
THE MODEL
Conceptual structure
Start
Design new
systems
Gross
irrigation
requirements
Evaluation of
operating systems
Input data field
Hydraulic
simulation
Computation of
emitters chart
Computation of
performance indicators
Occurrence of
runoff
N
Acceptable runoff?
End
Y
Spans
Emitters
Systems
DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH
CENTER-PIVOT SPRINKLER SYSTEMS
THE MODEL
Gross irrigation requirements
DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH
CENTER-PIVOT SPRINKLER SYSTEMS
THE MODEL
Hydraulic simulation
DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH
CENTER-PIVOT SPRINKLER SYSTEMS
THE MODEL
Selection the emitter chart
Compare
DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH
CENTER-PIVOT SPRINKLER SYSTEMS
THE MODEL
Calculation of the application rate
Run off
DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH
CENTER-PIVOT SPRINKLER SYSTEMS
THE MODEL
Performance indicators
DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH
CENTER-PIVOT SPRINKLER SYSTEMS
MODEL APPLICATION
Performance indicators in field evaluations
The results analyzed herein refer to field evaluations of centerpivot systems in operation in Alentejo (Portugal)
DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH
CENTER-PIVOT SPRINKLER SYSTEMS
MODEL APPLICATION
Performance indicators in field evaluations
Main problems were:
i)
high working pressure, ranging from 476 kPa to 555 kPa, much
above recommended pressure for systems with FSPS emitters;
ii)
high wind drift and evaporation losses due to small diameter of
droplets as a result of high functioning pressure of emitters; and
iii) application rates excessive relative to soil infiltration rates.
These problems result of poor design, mainly relative to the selection
of spray heads which were not in agreement with the existing
characteristics of the pressurized distribution network and the
characteristics of the soils and relief in the area.
DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH
CENTER-PIVOT SPRINKLER SYSTEMS
MODEL APPLICATION
Performance indicators obtained in DEPIVOT
The model DEPIVOT was used to simulate alternatives to the existing systems
L (m)
U (m/s)
Pp (kPa)
Qs (m3/h-1)
hf (kPa)
Y (mm)
UD (%)
CU (%)
Lucefecit
H233/4/5
440
2.5
325
248.5
44.0
9.0
92.3
97.1
Lucefecit
H116
168
3.14
200
42.6
4.6
94.8
96.8
Vigia
333
3.5
180
140.0
38.7
8.9
95.3
97.2
DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH
CENTER-PIVOT SPRINKLER SYSTEMS
CONCLUSIONS
The operation pressure is excessive
Runoff was
also often
produced
due to high
application
rates
Field evaluations of center-pivot
systems have shown that these
systems are often poorly
designed and the selection of
emitters is often inappropriate
Friction losses observed were often greater than 20% of
the operation pressure
Small drops
that easily
evaporate or
are drawn by
the wind
DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH
CENTER-PIVOT SPRINKLER SYSTEMS
CONCLUSIONS
The model DEPIVOT was conceived to support farmers in selecting new
systems and improving the existing ones.
DEPIVOT shows that it is possible to:
• achieve much better performances;
• reduce the operating pressure and save energy;
• control wind drift and evaporation losses,
• control runoff
The beneficial water
use.