Monetary Assessment on Multiple Functions of Irrigation Water for Paddy Fields in the Asian Monsoon Region March 18, 2009 Kazumi YAMAOKA, PhD International Network for Water and Ecosystems in paddy fields (INWEPF)

1 Background of monetary assessment Multiple functions of irrigation services provide huge benefit to many beneficiaries in addition to farmers. To share the broadened concept of Multiple Uses and Functions (MUFs) of irrigation water by policy makers and tax payers, monetary assessment can be a tool to make its value virtually visible. Flood mitigation, Ground water recharge, Preventing soil from erosion, Bio-diversity Stabilizing downstream river flow, Recreation, and etc. Promoting momentum and sustainable activities which aim at efficient and equitable water use consistent with the regional and socio-cultural needs → Accelerate to achieve MDG’s target Implement appropriate water policy by government Support by NGO and other non-farmers

2 Retardant flow to downstream rivers Multiple Functions of Water Management in Paddy Fields Flood mitigation InfiltrationDrainage Flood mitigation Temporary water storage during heavy rainfall Heavy rain in river basin Drainage canal Diverted water from rivers Irrigation canal Agricultural road Flood mitigation

3 Multiple Functions of Water Management in Paddy Fields Recharge of river flow and groundwater Ground water level Infiltration Drainage River Stabilizing river flow Recharging groundwater Drainage canal Agricultural road Conservation of aqua-ecosystem Re-use or Recycle of water for other sectors/users Irrigation canal Heavy rainfall Rivers Oceans Seas

4 Multiple Functions of Water Management in Paddy Fields Prevention of soil erosion and land slide Levees around paddy fields and standing pool of water in paddy fields protect farm soil from erosion caused by heavy rain. Stabilizing infiltration at moderate level Rain Slope Soil erosion Drainage canal Agricultural road Irrigation canal Rain Direct impact from heavy rain Easing of pore water pressure Prevention of land slide

5 Multiple Functions of Water Management in Paddy Fields The water network (corridor) connecting irrigation canal, paddy fields, ponds and woods is formulated around paddy fields. Through this network, aquatic ecosystem with a rich flora and fauna is formed. Formation of aquatic ecosystem

6 Multiple Functions of Water Management in Paddy Fields Farmers have recognized irrigation canals as a social overhead capital. And their collective water management, such as allocation of water and maintenance of irrigation structures, has inevitably promoted community systems and social capital among them. The water management has also been a base of traditional ceremonies, rituals and cultures with respect or worship to water and the nature. Formation of social capital, culture and traditional events

7 INWEPF, studied a trial calculation of the monetary assessment on 3 major multiple functions ・ Flood mitigation function ・ Groundwater recharge function ・ Soil erosion prevention function Calculation Methodology

8 available water volume stored by paddy field Annual amount of depreciation cost per unit efficient storage capacity of reservoirs (USD/m3/year) (1)Calculation Method: Replacement Cost Method (RCM) (2) Data Collection: Sending the questionnaire to the INWEPF member countries in July, 2008 and January, (But some data couldn’t be collected.) Example: Flood mitigation function Monetary value =×

9 Results of Assessment

10 Results of Study In the next step, refining the assessment and applying it to other functions are expected. Developing the tool for appreciating a holistic value of irrigation systems for rice paddy fields must realize more sustainable rice production in the future and contribute not only to eradicating hunger and poverty but also to solving global issues on food and energy. According to the trial assessment over 17 countries, the annual value of only 3 multiple functions out of various them are more than 800 USD/ha in average in addition to rice production value. Monetary assessment on 3 multiple functions of irrigation water for paddy fields can be carried out by RCM. Because of wide range of beneficiaries on the holistic value, it is important to facilitate sustainable investment by pubic sectors to irrigation systems for paddy fields.

11 (Reference) The way to assess multifunctional roles of paddy fields a) Flood Mitigation function STEP1 Calculation of function volume Efficient capacity STEP2 Calculation of unit monetary value Unit annual monetary value of flood prevention function of paddy fields Monetary Assessment of the Multifunctional Roles of Paddy Fields × available water volume stored by paddy fields calculated by area of paddies, level of height of levee in average, etc Annual amount of depreciation cost per unit efficient storage capacity of reservoirs (USD/m3/year) ×

12 STEP1 Calculation of function volume STEP2 Calculation of unit monetary value Monetary Assessment of the Multifunctional Roles of Paddy Fields × the ground water recharge volume from paddy field out of using ground water volume calculated by area of paddies, daily water requirement rate of paddy fields, annual precipitation, etc Water rate (USD/m3) (price of domestic water) × b) Groundwater Recharge function The groundwater recharge volume Unit substitution cost

13 STEP1 Calculation of function volume STEP2 Calculation of unit monetary value Monetary Assessment of the Multifunctional Roles of Paddy Fields × Different volumes between soil erosion volumes at cultivation abandonment and them as usual (USLE method) calculated by area of paddies, annual precipitation, slop length, steepness, etc Labor cost (USD/m3) × c) Soil erosion prevention function Soil erosion volume prevented Unit labor cost to excavate soil eroded

Aquaculture, duck raising, washing, cleaning, bathing, cooling, gardening, fire fighting, etc. Protect aqua-ecosystem, enhance water-related environment, form landscape, recharge groundwater aquifer, mitigate damage by flood, stabilize downstream river, etc. ･ Provide water from agriculture for domestic use during severe dry spells ･ Increase performance of paddy fields as outflow-retarding reservoirs during extreme floods ･ Create winter sanctuaries for migratory birds ･ Restore groundwater level for downstream city, etc. Multifunctionality of water collectively managed for paddy rice agriculture A. Benefits spread to public society through agricultural activity A-2. Benefits intentionally provided to the public A-1. Benefits automatically generated to the public B. Benefits gained by farmers and local community B-1. Multi-purpose use of water by farmers B-2. Supporting local cultural-religious activities Diagram for categorizing multi-functionality

15 B-1. Multi-purpose use of water by farmers A-1. Benefits automatically generated to the public A-2. Benefits intentionally provided to the public B-2. Supporting local cultural-religious activities Socio-economic development in Asian countries versus value of multifunctionality categorized into four characters