Coping with increased water scarcity: from Efficiency to Productivity

Transcription

1 Coping with increased water scarcity: from Efficiency to Productivity Theib Oweis Director, Integrated Water and Land Management Program, ICARDA, Amman, Jordan Presentation at the 2014 Symposium: Drought in the life, cultures and landscape of the great Plains 1-4, April Lincoln, Nebraska

2 IFPRI Washinton D.C., United States CIMMYT Mexico City, Mexico CIAT Cali, Colombia CIP Lima, Peru Bioversity Rome, Italy WARDA Bouake, Cote d Iviore IITA IBADAN, Nigeria ILRI Nairobi, Kenya ICARDA Aleppo, Syria ICRISAT Patancheru, India IWMI Colombo, Sri Lanka ICRAF Nairobi, Kenya CIFOR Bogor, Indonesia IRRI Los Banos, Philippines ICLARM Penang, Malaysa

3 Temperate dry areas

4 Water scarcity intensifying 1/3 of the world s population live in water scarce areas Many countries with chronic water scarcity Water for agriculture in dry areas is declining Climate change adds to the problems Energy competes Consequences Per capita annual m Water use per liter of biofuel production Liters ET Liters % Agriculture share of total Southern Total available water per capita Agriculture share of water irrigation per capita 1200 Mediterranean Chin a India US Brazil Cubic meter per capita Jordan Arab world World Europe North America % of total water resources

5 New water limited!!!! Surface, mostly tapped Ground, over exploited Marginal-quality, small amounts, environment, health Desalination, costly, environment, transport Water transfer, cost and politics Groundwater level (m below ground surface) Tel Hadya, Syria,

6 The context Water & food Food security- self reliance- self sufficiency Virtual water imports More food needed / less water available Irrigation Efficiency: Can improvements overcome water shortage? Modernizing irrigation systems? New directions & ned for change

7 Conventional coping strategies: insufficient!!! Increasing yield: needs more water Improving irrigation efficiency: only paper savings Modernizing irrigation systems: The fallacy!!! Demand management/ pricing water: not working in developing countries Yield (t/ha) ET (mm)

8 Typical furrow irrigation system

9 Field water balance Precipitation Transpiration Runoff Evaporation Irrigation Drainage Storage Deep percolation Seepage

10 Sprinkler irrigation One can under irrigate No DP / 100% application Eff 50% storage Eff. One can over irrigate 100% storage efficiency 50 % application efficiency

11 Trickle irrigation Under irrigation Application eff. 100% Storage eff. 50% Over irrigation Application eff. 50% Storage eff. 100%

12 Field water balance Precipitation Transpiration Runoff recoverable Evaporation Losses Irrigation Drainage Partially recoverable Quality losses Storage Deep percolation To ground water recoverable Seepage recoverable

13 Issues of irrigation efficiency Reflects the performance of irrigation system (engineering aspects) Ignores recoverable losses??? Nothing to do with the return to water (productivity) Wrongly used to judge the whole farm water management system Huge investment in modernizing irrigation

14 Modernizing irrigation: water savings! Does irrigation modernization save water? YES Does increasing Irrigation Efficiency from 50% to 80% save 30% water? NO How much saving then? Depends on: System changed and system adopted Irrigation management Crops and pattern Mostly in reducing evaporation and non beneficial use Is it worth the cost? Not necessarily

15 Modern systems: productivity Higher productivity is not only associated with water savings. Drip irrigation does: Provide better soil water due to frequent irrigation Fertigation more frequent and uniform Weed control The cost: Investment, Maintenance, Skill Salt accumulation needs periodical flushing Modernizing surface irrigation; ignored option

16 from efficiency to productivity

17 Water productivity: the concept Return WP = Unit of water consumed What return?? Biomass, grain, meat, milk (kg) Income ($) Environmental benefits (C) Social benefits (employment) Energy (Cal) Nutrition (protein, carbohydrates, fat) What water?? Quality (EC) Location (GW depth) Time available Consumed (depleted) Evaporation Transpiration Quality deterioration

18 Nutritional Economic WP Wp Calories/m3 $/m3 Potential water productivity improvement Biological WP kg/m3 Nutritional WP Protein gr/m3 Beef Beaf Lentil Lentil Wheat Wheat Potato 7 Olive Dates Beef Beef Lentil Lentil Wheat Wheat Potato Potato Olive Olive Dates

19 More food with less water It takes a litre of water to produce every calorie, on average

20 Potential WP improvements Reducing evaporation Improving management Enhancing genetic resources Great potential in developing countries

21 Scales and drivers to increase WP At the basin level: competition among uses (Env., Ag., Dom.) conflicts between countries Equity issues At the national level: food security hard currency sociopolitics At the farm level: maximizing economic return Nutrition in subsistence farming At the field level: maximizing biological output

22 20 Tradeoffs between water & land productivity Water productivty (kg/m3 x10) y = x x R 2 = Land productivtiy (t/ha)

23 Potential practices Supplemental irrigation Deficit irrigation Germplasm Cultural practices Water harvesting 2.5 Water productivity Water productivity (kg grain/ha-mm (Kg/m3) (kg/m3) rain) % of rainfall Water productivity (kg/m3) Rain water Evaporation Transpiration Supplemental irrigation water Irrgation water Full irrigation water Spring-sown Rain water Winter-sown N0 0.5 N50 N100 N150 Nitrogen application rate (kg N) No intervention 0 Micro WH Macro WH SI water FI water Rain water Rainfed 33% SI 67% SI Full SI Tel Hadya Jinderis Terbol

24 CC alleviation potential of supplemental irrigation Crop yield based on GCM IPSL-CM4: Ann. Precip: mm SI: mm 6.0 Yield (Mg/ha) Degrees centigrade Temp Increase in irrig. water demand but also increase in yield and WUE! CO Rainfed Supplemental Irrigation Sommer, Hussein & Oweis 2011

25 Conclusion Business as usual Thank you