MECARMetodologia para a Estimativa do Consumo de
Água de Rega em PortugalMethodology to Estimate the Irrigation Water
Consumption in Portugal
Pedro Leão de SousaTiago Mora Jorge
Technical University of LisbonHigh Institute of Agronomy
Center of Tropical Studies for DevelopmentStatistics Portugal
Target
To evaluate the amount of irrigation water used in each farm, by crop, during the crop year of 2009Difficulties
The farmers usually doesn't recorded the applied irrigation water
The meteorological conditions along the country presents a strong variation
The farm characteristics, in which concerns technological development, size and crops, are scattered
The skill of each farmer to handle and manage their irrigation system is quite different
To overcome these difficulties
Our team is developing a Methodology to Estimate the Irrigation Water Consumption in Portugal (MECAR), respecting and fitted to the national agriculture specificity.
This methodology includes
The use of a simulation model (ISAREG)
The meteorological data of evapotranspiration, precipitation and soil moisture content
The soil characteristics
The irrigation systems efficiency
ISAREG is a simulation model developed in the Technical University of Lisbon / High Institute of Agronomy by Prof. J.L. Teixeira (1994)
In which concerns the available evapotranspiration of the country, it was defined a set of influence zones, in view the application of the model results for each farm, inside each one of these zones
Meteorological Station
Center C1 – C20
North N1-N15
South S1 – S14
For each area of influence are run simulations with ISAREG, for the main type of soils
Finally, for each area of influence and type of soil the model is applied for each one of the crops cultivated in the area.
Temporary Crops PermanentCrops
For one zone of influence it is foreseen a number of simulations, in accordance with the following example:
Zone of influence N1
Crops Soilsmellon sandylettuce loamcorn claypotatoetomatoebeanorangepearpeachpasture
Number 10 3
Total number of runs
30
Expanding this exercise to the country:
ZONENumber of
simulations
North N1-N15 450
Center C1 – C20 600
South S1 – S14 420
Total number of simulations 1470
With the results of all these simulations can be
built a table with the form:
Influence Zone
Administrative área
Soil type
CropWater crop
consumption per ha
C1 Wcons N1 S C1
C2 Wcons N1 S C2
… …
Cn Wcons N1 S Cn
C1 Wcons N1 L C1
C2 Wcons N1 L C2
… …
Cn Wcons N1 L Cn
C1 Wcons N1 C C1
C2 Wcons N1 C C2
… …
Cn Wcons N1 C Cn
C1 Wcons N2 S C1
C2 Wcons N2 S C2
… …
Cn Wcons N2 S Cn
C1 Wcons N2 L C1
C2 Wcons N2 L C2
… …
Cn Wcons N2 L Cn
C1 Wcons N2 C C1
C2 Wcons N2 C C2
… …
Cn Wcons N2 C Cn
N2
Freguesia N2f1 Freguesia N2f2
…. Freguesia N2fn
Sandy
Loam
Clay
Sandy
Loam
Clay
N1
Freguesia N1f1 Freguesia N1f2
…. Freguesia N1fn
(Small administrativeunit)
These values of water crop consumption have to be corrected upon the irrigation system efficiency
For a given irrigation system are considered 3 efficiency levels:
Level 1 – Low efficiencyLevel 2 – Intermediate efficiencyLevel 3 – High efficiency
Qualification factors (QF)
[1]
Relative weights
(RW)
[2]
Practical example
QF
[3]
Weighed level
[2]x[3]
Final weighed
level (FWL)
Legal personality
of holding
(1 to 3)
10
Single producer
110
2,35
Farmer age
(1 to 3) 15
Age 45-64
2 30
Farmer instruction
(1 to 3)35
Secondary school
270
Agricultural training area
(1 to 3)40
Practical agriculture
course
3
120
Irrigation system efficiency evaluation
Level 1 – Low efficiency FWL < 1,5
Level 2 – Intermediate efficiency 1,5 ≤ FWL < 2,5
Level 3 – High efficiency 2,5 ≤ FWL 3,0
Level of efficiency and irrigation efficiency
The irrigation efficiency (Ei) in a given farm must be obtained by the product of the maximum irrigation efficiency (Eimax) and a factor of correction (Fc) fixed as 0,7; 0,85 and 1, according to:
Level 1 – Low efficiency Eimax x 0,7
Level 2 – Intermediate efficiency Eimax x 0,85
Level 3 – High efficiency Eimax
In the example presented and for a sprinkler irrigation system, with a potential maximum efficiency (Eimax) of 75%:
FWL = 2,35 Level 2 (Fc=0,85) Ei = 75 x 0,85 = 63,75 %
Influence Zone
Administrative área
Soil type Crop
Water crop consumption
per ha
C1 Wcons N1 S C1
C2 Wcons N1 S C2
… …
Cn Wcons N1 S Cn
C1 Wcons N1 L C1
C2 Wcons N1 L C2
… …
Cn Wcons N1 L Cn
C1 Wcons N1 C C1
C2 Wcons N1 C C2
… …
Cn Wcons N1 C Cn
Sandy
Loam
Clay
N1
Freguesia N1f1 Freguesia N1f2
…. Freguesia N1fn
Farm xy
Crop C2
Wcons N1 S C2 4750 m3/ha
Area C2 = 3,5 ha
Wfc = 16 625 m3
Ei
63,75 %
Real Wfc = Wfc/Ei
16 625 /0,6375 = 26078 m3
The simulation model ISAREG will be previously used with a set of 20 years of meteorological data to generate all the information above mentioned.
It is foreseen that some field observations will be carried out during the Spring 2009 to validate this methodology.
At the beginning of 2010, if possible, all the information achieved with the model for the average meteorological data (set of 20 years), will be corrected with simulations based on meteorological data of year 2009.