Global debate on irrigation water use

Transcription

1 INCREASING or REDUCING IRRIGATION WATER Global debate on irrigation water use Increasing by 15-20% for food security or Reducing by 10% for eco-environment What to do? Global issues on the water saving in rice paddy WWF-2 focused on irrigation efficiency for food production: Through improving irrigation efficiency! Saving irrigation water and diverting to drinking, ecosystem water! Conserving water than developing as pressure on environment! WWF-3 focused on multi-function of paddy irrigation : Possible to increase food production without increasing irrigation water? Multi-function of paddy farming should be preserved for culture and ecology How to reduce the water use while preserving the current eco-system? WWF-4 focused on integrated water resources management : Still irrigation water is most responsible for the over-consuming water Integrated water resources management was recommended O & M cost should be covered by private sector than by public sector 1

2 Foundation of INWEPF and PAWEES Irrigated rice farming in the paddy has been developed in the Asian monsoon region not only to provide stable food security, but also to maintain the multifunctionality such as culture, ecology, and environment in the rural society But, the social effects of irrigated paddy and the economic values of multifunctionality are not clearly defined, because of a lack of reliable data and suitable evaluation techniques After having the multifunctionality session in WWF-3 in Kyoto 2003, the INWEPF and PAWEES were officially founded The purpose of PAWEES is to study multi-functionality of irrigated paddy fields in acadedmic way and propagate its importance to the Western countries where cultivating dry crops and not being familiar with rice farming PAWEES has annual conference and publishes quarterly academic jounal PWE The purpose of INWEPF is to study the food security and poverty alleviation, sustainable water use and share the partnership Its activities affect the decision makers of national policy to allot a proper amount of budget for agriculture and reflect the facts to the world trade negotiation of agricultural products 6th PAWEES Conference and Agenda meeting Agenda1: Engineering Accreditation system for Agricultural Engg Education in paddy farming regions Agenda2: Establishment of new agricultural engineering category in the APEC engineering system Agenda3: Upgrading the PWE (Paddy and Water Environment) journal Agenda4: Textbook for Agricultural Engineer Ethics and Ecological Engineering in Paddy farming 2

3 Connect, Contact, Tai Cheol, Kim ( ) 6th INWEPF Steering meeting and symposium Date:16-18 November 2009 Venue: JICA Research Institute, Tokyo Participant:16 member countries, 2 int l organization with 100 person Steering meeting WG1: multiple role of paddy fields (by Malaysia) WG2: Vision, policy and informatio n dissemination (by Korea) WG3: Contribution to technical coo peration (by Japan) 3

4 Bangladesh, Cambodia, China, India, Indonesia, Japan, Korea, Laos, Malaysia, Myanmar, Nepal, Pakistan, Philippines, Sri Lanka, Taiwan, Thailand, Vietnam Report in the WG-CROP, ICID Saving irrigation water and/or Conserving eco-system in rice paddy 2011 Oct 18 Tai Cheol, Kim Professor, Chungnam National University, Korea 4

5 WATER BALANCE IN THE PADDY Watershed area : 376 sq km Benefit area : 8,788 ha Storage capacity : 47MCM to investigate how much water is applied, wasted, and can be saved In the district of Yedang reservoir for 30yrs (Kim, 2004) Year Rain fall Inflow Run off ratio Amount of irrigation water (8,788ha) Unit mm 10 3 m3 % 10 3 m3mm % Rain in irri season ( mm ) Eff rain fall ( mm ) ET ( mm ) Percola -tion ( mm ) Net duty of water ( mm ) Water applied ( mm ) , ,740 1,285 1,224 1,111 1,094 1,191 1, , , , , , , , , , , ,508 71,105 69, ,998 83,037 95,217 67,042 69, , , , , ,528 1, , ,475 1,198 1,175 2,311 1,636 1,571 1,139 1,244 1,874 1,794 Mean 1, , , ,383 5

6 Average annual water balance in the paddy field Evapo-transpiration 659 mm Precipitation 946mm (Eff581) Surface runoff 365 mm Irrigation 1,565 mm Return flow 995 mm? Target to save or conserve Percolation 1,487mm Deep Percolation mm R i v e r Intake Rain ET 1,565mm Total amount of water = 2,146 (100%) Eff rainfall (581) = Rainfall(946) Flood flow(365) Total amount of water 2,146 = 1, Cropping & facilities 995 Return flow Percolation 995 (46%) Flood flow 365 Ground water Target to save : Managing water of 995mm for cropping and facilities circulated as returned flow is blamed as wasted water, but it is functioning to improve the ecosystem services 6

7 Inlet of irrigation canal Outlet of drainage canal Waste of water or sound circulation for eco-system? Managing water of 995mm is circulating the paddy fields continuously and functioning to purify water quality, conserve ecosystem, and recharge groundwater in watershed scale 7

8 Waste of water or Sound circulation for eco-system (100mil m3 ) Safe freq Area 10,000 ha Evapotranspirat ion Percolation water in plot Eff rainfall Net water required Facility managing Supplied by facility Total irrigation water use Return water Broad water required 10 yr yr Irrigated 5 yr yr yr Total Non-irrigated (153) * Sub-total Irrigated upland Non-irrigated 838 Sub-total Total ALTERNTIVES for WATER SAVING or MULTIFUNCTION In the case 1, it is currently to supply water with ET of 659mm, percolation of mm, and management of 995mm which has a function of return flow and conserve the present sound eco-system (more water, more rice & eco-system and to avoid the damage of repeated cultivation) In the case 2, it is enough to supply water with ET and percolation of mm essential to rice paddy farming But, there is no return flow and so no water is available to conserve the present sound eco-system (less water, poor rice taste & poor eco-system) In the case 3 of most extreme, it is enough to supply water only with ET of 659mm which is actually consumed by the rice plant In this case, sprinkler irrigation is available for upland rice and/or dry crops (less water, less rice and poor taste & eco-system) In case of 4, to find out the amount of target to save ranging from max 995mm to a certain optimal amount (less water, more rice & eco-system and to avoid the damage of repeated cultivation) 8

9 Case 1 Case 2 Case 3 Case 4 We are afraid paddy is converted into upland & the eco-system is totally changed Wisdom based on Land & Water (JIID, 2003) After WTO, cultivated paddy has been reduced by half in Taiwan, drastic change of the eco-system such as loss of scenery & landscape and groundwater level & land subsidence 1,600 species of insect inhabit a paddy field near the Omiya suburbs in Japan Wisdom based on Land & Water (JIID, 2002) 1,600 species of insect inhabited in paddy field 100 or more species of insect inhabited in dry field near the Omiya suburbs in Japan near the Omiya suburbs in Japan 9

10 Response on the water balance from agricultural sector It is true that continuous flooding irrigation in paddy fields consumes lot of water much more than it needs But, it is also true that only irrigation techniques that farmers have adapted to the local conditions through a long process of trial and error in the history have been succeeded to the descendants Supplied water is not wasted, but circulate and reuse repeatedly It contributes tes a lot to conserve e eco-system stem services in the watershed Consequently, farmers are maintaining the continuous flooding irrigation adapted to environments in the history Values of the eco-system services in paddy The 21 st century is called Water century or Century of ecology Paddy irrigation have multiple roles not only food production, but also flood control, ground recharge, soil erosion mitigation, landscape, air & water purification, and regional water supply such as fire fighting or waterway Furthermore, paddy irrigation has played a significant role for sound hydrological cycle and wide range of amenities related to community, culture and environment Water for eco-system services increase its importance in water management related to tackling climate change, conserving biodiversity and other issues 10

11 Improving the eco-system services Natural environment and rural culture in Asian monsoon region are closely related to paddy irrigation agriculture Seasonal irrigation practices not only determine the hydrologic regime, but also form the aquatic environment affluent in biodiversity, the beautiful landscape in seasons, and the history and culture of the society in the watershed Especially under the recent changes of the situations, ie urbanization by rapid economic growth, and increase of extreme drought and flood risks by the climate change, it is important for all the stake holders including farmers to make necessary actions for enhancing the environment, the eco-system services, and the traditional cultures Table Valuation on Multi-functionality of Paddy Farming in Korea : physical and conservation functions only (unit: 100 million KRW) Items of multifunctionality Eom (1993) RDA (1994) Oh (1995) Yoon (1996) KREI (2001) Park (2003) Flood control 15,824 16,000 8,655-13,305 14,057 Water storage - - 9,839 10,073 11,427 23,857 Improving water quality 59,615 59,611 12,325-11,946 3,887 Soil erosion control 667~ 2,061 2,173-19,047 4,532 1,648 Waste disposal Atmosphere purification 27,979~ 56,869 56,773 46,246 3,076 22, ,705 Reducing temperature - 2, ,062 Keeping nature scenery - 3, Total (billion US$) 104~

12 How much and how to save irrigation water? The issue to debate is how much water could be reduced out of managing water without reducing yield and how much agricultural water can be saved while conserving the sound eco-system services and rural amenity? Paddy field irrigation has the Multifunctional roles" of recharging groundwater, mitigating floods, providing a domestic water supply and water for fish farming, passing on traditional culture, protecting biodiversity, forming aquatic landscapes, environmental services and other socio-economic effects Since paddies consume only some of the water withdrawn, it is important to improve recycling so that seepage from paddies can be reused downstream Deliberate research and discussion should be carried out SUMMARY and RECOMMENDATION 1) Irrigation in paddy field has the Multifunctional roles" of recharging groundwater, mitigating floods, providing domestic water supply, water for fish farming, passing on traditional culture, protecting biodiversity, forming aquatic landscapes, environmental services, and other socio-economic effects 2) Vitalizing the Rural Improvement Act to keep the agricultural water right and to develop the rural water for more amenity 3) What is the optimal amount of irrigation water for saving and rural water for conservation of eco-system? 4) Practical strategy and incentives system for farmers voluntarily to save water 5) Conserving the eco-system by the irrigation networks to boost up green tourism 6) How much irrigation water in rice paddy can be saved while conserving/improving the eco-system services should be investigated 12

13 CONSERVING ECO-SYSTEM Agriculture + Water + Eco-system = Amenity? Prof Kim s equation 13