Evolving Thinking on Agricultural Water Productivity

Transcription

1 Evolving Thinking on Agricultural Water Productivity Meredith Giordano Going Beyond Agricultural Water Productivity Workshop World Bank, Washington DC December 8, 2014

2 Maria Grazia Bellio/IWMI Karen Coniff/IWMI Karen Coniff/IWMI Presentation Summary Water efficiency to productivity Areas of research Lessons learned

3 Water efficiency to productivity: A shift in IWMI s research focus Rationale: Growing demand for and competition over scarce water supplies: How can we grow more food with less water? Limitations of classical, supply driven indicators: Focus on losses from storage, conveyance, distribution, application No distinction between dry and wet water savings at a basin scale Seckler, 1996 One of the most important yet least appreciated facts about water basins is that a substantial amount of water is recycled between the sources and the sinks.

4 Water efficiency to productivity: A shift in IWMI s research focus Key considerations: The extent to which water is recycled in a basin Whether a basin is open or closed Advocated improved water productivity through: Increase output/unit of evaporated water Reduce losses of usable water to sinks Reduce water pollution Reallocate water from lower to higher value Seckler, 1996

5 Key areas of research 1. Terminologies and definitions. 2. Methodologies and tools to measure water productivity. 3. Applied research to understand opportunities to increase water productivity and save water.

6 1. Terminologies and definitions Classical efficiency Crop ET-effective precipitation/application Application efficiency, minimize losses Net and effective efficiency: Address capture/re-use (and leaching requirements) (Jensen 1967; Keller & Keller 1995) Water productivity: Output of a given system in relation to water consumed Multiple uses and sequential re-use within a basin Multiple sources of water Multiple scales

7 1. Terminologies and definitions Basic Expression: WP = output/water consumed Variations Molden et al Molden Cook et et al. al.,

8 2. Methodologies and tools: Water accounting How much water is actually depleted, where and for what use, compared to that available and the portion diverted? Molden, 1997

9 2. Methodologies and tools: Water accounting Identifies total water depletions. Distinguishes between process and non-process depletions. Estimates low or non-beneficial depletions. Accounts for downstream commitments. Molden, 1997

10 2. Methodologies and tools: Modeling/RS Crop WP, Indo-Gangetic Basin Cai et al Turral, 2006

11 2. Methodologies and tools: Modeling/RS Estimate average current and potential water productivity. Target locations where large improvements in water productivity are possible. Identify entry points to improve water productivity, generate real water savings. Understand the potential consequences. Turral, 2006

12 $/m3 2. Methodologies and tools: Water accounting WP GVPet WP in subdivisions of Rechna Doab Malhi Nokhar Sagar Sadhoke Gujjranwala Shahdara Chuharkana Naushera Sangla Muridke Paccadala Sheikhupura Kot khuda yar Sikhanwala Uqbana Mohlan Aminpur Wer Buchiana Veryam Mangtanwala Tandilianwala Dhaular Tarkhani Kanya Haveli Bhagat Sultanpur Sub-division Ahmad, 2004

13 $/m3 2. Methodologies and tools: Water accounting Tapping uncommitted outflows. WP GVPet WP in subdivisions of Rechna Doab If we know why the values are low or high, then we can determine whether WP can be improved and how, by, e.g Increasing productivity per unit of water consumed Reducing non-beneficial depletion. Reallocating water among uses Malhi Nokhar Sagar Sadhoke Gujjranwala Shahdara Chuharkana Naushera Sangla Muridke Paccadala Sheikhupura Kot khuda yar Sikhanwala Uqbana Mohlan Aminpur Wer Buchiana Veryam Mangtanwala Tandilianwala Dhaular Tarkhani Kanya Haveli Bhagat Sultanpur Sub-division Ahmad 2004

14 3. Applied Research: Water productivity in context Water productivity across time and space Impact of interventions on conservation goals and other development objectives

15 3a. Applied research: Water productivity and place High water productivity levels in one region may be indicative of what is possible, but Crop water productivity, 10 Basins (figures below from Nile and Indus-Ganges basins) Cai et al., 2011

16 3a. Applied research: Water productivity and place location specific factors must be considered. Effect of milk production on rice WP, Krishna Basin, India Krishna Basin, 2004 Biggs, 2004 Key finding: Water productivity values and pathways for improvement must be understood within their specific setting.

17 3b. Applied research: Water productivity and perspective Two systems, two opportunities (to improve WP), two different outcomes. Zhanghe Irrigation System (ZIS), Yangtze River Liuyuankou Irrigation System (LIS), Yellow River Molden et al., 2007

18 3b. Applied Research: Water productivity and perspective Incentives and pressures to save or reallocate water by user group and scale Adapted from Molden et al Adapted from Molden et al Key finding: Policies and strategies for changing water use and management must aim to align the objectives and incentives across user groups/scales, to obtain society-wide goals for improved water use.

19 3c. Applied research: Water productivity and water savings Rice-Wheat Zone, Punjab Province, Pakistan Ahmad et al., 2006 Key finding: Even when technologies decrease applications per unit of crop output, they may not decrease actual water consumption (in fact may increase) unless institutional arrangements are in place to limit demand or reduce available water.

20 3d. Applied research: Water productivity and poverty Development Trajectory, 10 Major River Basins Water Productivity and Poverty, Ganges Basin WP interventions can either reinforce or reduce inter-household inequities. Identifying pre-existing inequities in water access within and among communities will support better targeting of poor communities Kemp-Benedict et al., 2011 Clement et al., 2011 Key finding: There is no simple link between water scarcity, poverty and equity. It is more relevant to understand the influence of water-related variables on poverty together with the livelihood strategies and institutional capacity to manage trade-offs.

21 Key Lessons The concept of water productivity fostered a move from a theoretical discussion on the need to produce more food with less water to a practical discussion (should, where, why, and how?). Proper water accounting is fundamental. Water productivity is not a goal in and of itself. It is one of many factors involved in improving agricultural productivity and supporting poverty alleviation, food security and ecosystem functioning. Single indicators can mask the complexity and trade-offs required to achieve development outcomes. The aim of the workshop is to reach more clarity -- and possibly a more integrative view -- on "agricultural water productivity" and, most likely, broader approaches to help address rising water and food security concerns.

22 Thank you

23 Ahmad, M.D., et al A comparative analysis of crop water productivity of rice-wheat and cotton-wheat rotations in Rechna Doab, Punjab, Pakistan. New directions for a diverse planet. In 4th International Crop Science Congress. Ahmad, M.D., et al Water saving technologies: myths and realities revealed in Pakistan's rice-wheat systems. IWMI Research Report No 108 (IMWI) Cai, X.; et al An assessment of crop water productivity in the Indus and Ganges river basins: Current status and scope for improvement. Colombo, Sri Lanka: International Water Management Institute. 30p Cai, X., et al Producing more food with less water in a changing world: assessment of water productivity in 10 major river basins. Water International 36(1): Clement, F., et al Enhancing water productivity for poverty alleviation: Role of capitals and institutions in the Ganga Basin. Experimental Agriculture 47(S1): Jensen, M.E Evaluating irrigation efficiency. Journal of irrigation and Drainage 93(IR1):83 98 Jensen, M.E Water conservation and irrigation systems. In: Climate-technology seminar proceedings, Colombia, Missouri, October 1977, pp Keller AA, Keller J Effective efficiency: a water use efficiency concept for allocating freshwater resources. Discussion paper 22, Center for Economic Policy Studies, Winrock International. Kemp-Benedict, E., et al Connections between poverty, water and agriculture: evidence from 10 river basins. Water International 36(1): Molden, D Accounting for water use and productivity. IWMI/SWIM Paper No. 1, International water management Institute, Colombo, Sri Lanka, 25 pp Molden, D., et al Agricultural water productivity and savings: Policy lessons from two diverse sites in China. Water Policy 9(S1): Molden, D., et al Improving agricultural water productivity: between optimism and caution. Agricultural Water Management 97(4): Seckler, D Revisiting the" IWMI paradigm:" Increasing the efficiency and productivity of water use. International Water Management Institute (IWMI): Colombo, Sri Lanka