Concepts of water productivity

for irrigated saline lands

Water Management and use of crop simulation models AquaCrop

2-13 October 2016

Richard Soppe

• Innovation

• Partnership

• Impact

Outline

- crop water productivity

- economical water productivity

- water delivery efficiency

- irrigation efficiency

- other efficiencies

Crop water productivity

-The production of biomass, or yield, per unit water consumed

-Thus not related to irrigation water delivery, but related to

the consumed water Evaporation + Transpiration

- Can be related to total biomass production, or to actual yield.

Crop water productivity

)(

)(

)/(

3

3

mpirationevapotransactualET

kgyieldcropmarketableY

mkgtyproductiviwatercropCWP

ET

YCWP

act

act

act

act

Wheat - example

Economic water productivity

-The value of production (income – cost) per

unit water consumed

Remote sensing based

Economic water productivity

0 1 2 3 4 5CWP Fresh Banana (kg/m3)

0

0.01

0.02

0.03

norm

alized n

um

ber

of

pix

els

(-)

-3 -2 -1 0 1 2 3Economic cwp (R/m3)

0

0.005

0.01

0.015

0.02

0.025

norm

alized n

um

ber

of

pix

els

(-)

400 800 1200 1600ETa (mm)

0

0.004

0.008

0.012

0.016

0.02

norm

alized n

um

ber

of

pix

els

(-)

400 800 1200 1600ETa (mm)

0

0.004

0.008

0.012

0.016

0.02

norm

alized n

um

ber

of

pix

els

(-)

340 740 1140ETa (mm)

Areas with lowest

bio-physical cwp

first out of prod

Areas with lowest

economic cwp

first out of prod

Quota per hectare

targets largest per

hectare users first

Use is reduced

proportionally, i.e.

in an equal way

Irrigation efficiency

- Many different definitions. Always think about HOW to use it.

- Which indicator gives us what information?

H Fairweather - ‎2009

Soil and water balance, water flow in

saturated and unsaturated soil, infiltration

rates, hydraulic conductivity

Water Management and use of crop simulation models AquaCrop

2-13 October 2016

Richard Soppe

Water fluxes in an irrigated field

7

Salt accumulation as a result of evaporation

Water fluxes transporting salts

1. Irrigation sources

2. Deep percolation

3. Drainage out of the field

4. Internal drainage from the root zone

5. Regional groundwater to the drain

6. Groundwater upflow into the root zone

7. Evapotranspiration of water and salt transport to soil surface

Daily salt load into and out of

the San Joaquin Valley

Salinity at a regional scale

Water and salt balance

I x ECi

P

ET

Root

zone

Watertable

R* (= R - G) x ECe

Schematic Lysimeter

Schematic Lysimeter

RAIN + IRRIGATION

GROUNDWATER UPFLOW

DRAINAGE

EVAPOTRANSPIRATION

Daily ground water contribution

Soil Water Sensors

Soil water measurements

NO GROUND WATER

GROUNDWATER

Shallow depth (60 cm) =

dry

Deeper depth (100 cm) =

wet

Crop water requirement and implications for

water demand

Water Management and use of crop simulation models AquaCrop

2-13 October 2016

Richard Soppe

• Innovation

• Partnership

• Impact

Outline

- Crop water requirement

Evapotranspiration…

Crop coefficients

Reality

- Water demand implications

• Innovation

• Partnership

• Impact

Evapotranspiration

PAGE 6

FAO 56

Reference evapotranspiration equation

a

s

a

aspan

r

r

r

eecGR

E

1

ceresisairbulkr

ceresissurfacebulkr

tconscpsycometri

densityairmean

airofheatspecificc

airofdeficitpressurevaporee

fluxheatSoilG

radiationNetR

iprelationshetemperaturpressurevaporsatofslope

fluxheatlatentE

a

s

a

p

as

n

tan

tan

tan

PAGE 19

FAO 56

Reference evapotranspiration - measurements

ETref - ICBA

Evapotranspiration calculations

Water Management and use of crop simulation models AquaCrop

2-13 October 2016

Richard Soppe

ET ref – daily time step

PAGE 24

][tanhom

][

][

][

][22

][2

][

][

34.01

273

900408.0

1

1

1

12

12

2

2

CkPatconsetricpsyc

CkPacurvepressurevapourslope

KPapressurevapouractuale

KPapressurevapoursaturatione

smheightmatspeedwindu

CheightmatetemperaturairT

daymMJdensityfluxheatsoilG

daymMJsurfacecroptheatradiationnetR

u

eeuT

GR

ET

a

s

n

asn

O

Calculation exercise – input parameters

PAGE 67

Dubai, 9 Oct 2016

35

25

30

30

1.8

30

0.243

0.067

1.612

0.692

0.191

5.529

Calculation exercise - vpd

PAGE 67

35

25

5.623

3.168

4.486

75

25

2.376

1.406

1.891

2.594

Calculation exercise – radiation

PAGE 6825.10

283Oct

0.8

35

25

1.891

30.8

20.0223.12

0.86615.4244.21

38.7541.480.147

0.866 0.8194.9910.4

10.44.25

Calculation exercise – ETref

PAGE 68

0.692*4.25=2.94

0.191*5.529*2.594=2.74

5.7

Calculation exercise – ETref

http://extension.uidaho.edu/kimberly/2015/06/ref-et-reference-evapotranspiration-calculator/

A unique Center of Excellence

looking at Agriculture for Tomorrow

Thank youFor more information and ICBA publications visit

www.biosaline.org

International Center for Biosaline Agriculture (ICBA) is an international, non-profit organization that aims to strengthen agricultural productivity in

marginal and saline environments through identifying, testing and facilitating access to sustainable solutions for food, nutrition and income security.