The tradeoffs between water savings and GHG emissions

in irrigated agriculture

Shahbaz Mushtaq, Tek Maraseni, and Kate Reardon

SmithAustralian Centre for Sustainable Catchments

University of Southern Queensland

Presentation Outline

• Background, aims and objectives

• Methods: integrated modelling framework

• Results and discussions

• Conclusions and recommendations

• Further research

Background

• Significant concerns about the longer term impact of climate change and climate variability on water availability.

• Government’s water and environmental policies (such as new MDB plan and water buyback) further increasing pressure on irrigators.

• The conversion of surface irrigation systems to more efficient pressurised systems has been heralded as an integral way of increasing water use efficiency.

• But pressurised irrigation technologies may increase energy consumption and greenhouse gas (GHG) emissions

• Policy conflicts: Water for the Future program and possible introduction of Carbon Tax/ETS

o To quantify the tradeoffs between water savings, economic impact and GHG emissions due to technological change in the irrigation industry

o Specific objectives are:

To estimate a range of water saving for different crops using hydrological modeling;

To quantify GHG emissions as a result of new irrigation technologies using both case studies & general approach; &

To determine the tradeoffs between water savings, economic impacts, energy consumption & GHG emissions by developing & analyzing irrigation transformation scenarios

Objective

Integrated Modelling Framework

Integrated framework for assessing trade-offs between water savings, economics, energy use and GHG emissions

Energy and GHG evaluation

Hydrological Modelling

Cost and & benefits evaluation

Integrated EconomicAnalysis

Tradeoffs between water saving, energy

use and GHG emission and economic profit

Field experiment, SWAP modelling, reviews and farmers assessment about possible water savings

Whole farm GHG modelling:• Irrigation technology change

and application• Farming practices and inputs

Net Present Value, Benefit Cost Ratio (BCR), and Break-even Water Savings

Application of the Integrated Framework

• Crop/field level approach: Focused on major crops for generalised analyses of water and energy use, productivity and economics associated with the adoption of new irrigation technologies.

• Farm level case study approach: Five case studies were undertaken to road test the integrated framework involving finer-scale farm-level variability and to inform the more generalised integrated analysis associated with the adoption of new irrigation technologies.

• National scale approach: Using more generalised outcome from crop level analysis, three nationwide irrigation scenarios were developed (without incorporating changes in inputs and practices)

Key Results 1:

Generalised Crop level Water, GHG and Economic

Evaluation

Potential Water Savings

Source: SWAP modelling; Khan et al. (2004a; 2008a); Khan & Abbas (2007); ACIL Tasman (2003); Rendell McGuckian (2002); Qureshi et al. (2001), Jackson (2009); Reynolds & Jackson (2007); EconSearch (2005); O'Neill et al. (2008) Harris (2007); Wood & Finger (2006); Foley and Raine (2001); DPI NSW (2010); Hickey et al. (2006)

GHG Estimates

Economic Evaluation

Crop Level Summary

• Only changes in irrigation technology were considered.

• A range of water savings is achievable, with high-end savings possible with best practice management.

• Conversion of irrigation technology can be economically viable except in the case of grain crops.

• Inclusion of a GHG emission value reduces the economic gain but this was not as influential as water savings, yield gains and labour savings.

Key Results 2:

Farm level detailed case studies approach

Case studies characteristics

Integrated tradeoffs matrix

Case Study Summary Whole farm GHG modelling considers two levels of GHG impacts

(i) changes in irrigation technology change (‘irrigation-related emissions’), and

(ii) changes in irrigation technology change plus associated changes in farming practices and inputs (‘total emissions’)

The use of new irrigation technologies may increase irrigation related emissions but decrease total emissions

Trade-offs were apparent when conversion to the pressurised irrigation system was evaluated in terms of irrigation related emission, except when hand-shift & role-line irrigation systems were replaced with pressurised irrigation systems.

But, when total emissions were considered, net reduction in GHG was observed (synergies), due to changes in the input use.

N.B. reduction in agrochemical-related emissions may have been due in part to new experience with precision agriculture

Key Results 3:

Nationwide irrigation transformation scenarios

(without considering changes in farm level inputs)

Nationwide Irrigation Transformation Scenarios Details

Scenario 1: Reducing the total area of surface irrigation systems from 44% during 2008-09 to 25% and replacing it with drip irrigation (40%) and sprinkler irrigation systems (60%);

Scenario 2: Reducing the total irrigation area under old inefficient labor & energy intensive portable & hose sprinkler irrigation systems from 16% during 2008-09 to 8% and replacing it with drip (50%) & sprinkler (50%) irrigation systems.

Scenario 3: Increasing the drip irrigation area on horticultural crops from 13.3% during 2008-09 to 20% of the total irrigated area.

Scenario 1: Trade-offs between water saving, energy use & GHG emissions

Scenario 2: Trade-offs between water saving, energy use & GHG emissions

Scenario 3: Trade-offs between water saving, energy use & GHG emissions

Irrigation technology transformations scenario summary

Only changes in irrigation technology were considered.

Two of the three scenarios tested showed tradeoffs between water savings and GHG emissions, with water savings through conversion of irrigation systems increasing both energy consumption and GHG emissions

Significant benefit in terms of water savings and GHG reduction can be achieved when replacing older inefficient and energy-intensive systems, such as hand shift and roll-line sprinkler systems

Conclusion & Policy Implications

• Modernisation of irrigation technology alone cannot deliver multiple benefits unless farming systems are optimised to include irrigation management and input management to reduce GHG emission.

• We suggest priority should be given, in the implementation of on-farm infrastructure investment policy, to replacing older inefficient and energy-intensive sprinkler irrigation systems such as hand shift and roll-line.

• The tradeoffs analysis illustrates a critical point, that both mitigation and adaptation need to be evaluated at the same time in order to optimise economic investments in irrigation technologies while managing climate change.

Further research

A comprehensive study of water consumption and GHG emissions across full cropping rotations is necessary.

Quantification of N2O emissions factors for a number of crops with different irrigation technologies is crucial.

Research which investigates soil carbon levels through the soil profile under different irrigation technologies is required.

In 4 out of 5 case studies, the adoption of new irrigation technology reduced farm inputs & thus GHG emissions. Whether the reduction is due to new irrigation technology or experience (precision farming) should be investigated.

National Water Commission Case study farmers Reviewer of the project report

Acknowledgements

Thank you