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.