1. Irrigation Australia/7 th Asian Regional Conference Assessment of Water Supply Capability in Agricultural Reservoirs according to Climate Change Tuesday 26 June 2012 Na-Young Park, Jin-Yong Choi, Seung-Hwan Yoo, Sang-Hyun Lee Department of Rural Systems Engineering, Seoul National University imny11@snu.ac.kr http://rwiel.snu.ac.kr

2. ContentsContents 2. Methodology 2. Methodology 3. Results and Discussion 3. Results and Discussion 4. Conclusions 4. Conclusions 1. Introduction 1. Introduction

3. 1. Introduction

4.   10% of land area is paddy fields and about 80% of the paddy fields are irrigated in South Korea.   Reservoirs supply about 60% of paddy fields as the main water resources, and others including pumping stations and headworks supply about 40%. Irrigation in South Korea (National Statistical Office, 2010) Paddy field

5.   South Korea’s agricultural reservoirs  Scattered in the nation, aged facilities, various size Agricultural reservoirs in South Korea

6. Climate change and agricultural reservoirs   Agricultural reservoirs have two different operations for irrigation and non-irrigation season  During irrigation season  Supplying stable agricultural water  During non-irrigation season  Storing water for irrigation   Climate change impacts on irrigation requirement  Temperature rising increases evapotranspiration  Possibly increasing irrigation requirement  Increasing rainfall  Opportunity for decreasing irrigation requirement  Altering seasonal rainfall amount and intensity  Increasing or decreasing effective rainfall → Impacts on water supply capability of agricultural reservoirs (Ahn et al., 2002), (KMA, 2009)

7.   To analyze the irrigation water supply capability of agricultural reservoirs - about 10-year design drought return period - for RCP (Representative Concentration Pathways) scenarios - using reservoir water-balance model ObjectivesObjectives

8. 2. Methodology

9. Flow chart (2.6, 8.5)

10.   Case 1: 3~7 year drought return period   Case 2: 10-year drought return period   Selected 16 reservoirs in 8 provinces Study area ProvincesReservoirsReturn period Effective storage Capacity (10 3 ton) Gyeonggi Docheok (A)5701 Jungri (B)10532 Gangwon Gungchon10772 Ucheon5949 Chungcheong nam Sinhyu101317 Gusu3228 …………

11. Climate change data   Emission scenarios  RCP (Representative Concentration Pathways) : 2.6 and 8.5   GCM (General Circulation Model)  CanESM (The second generation Canadian Earth System Model) in CMIP5(Coupled Model Intercomparison Project Phase 5)   Downscaling  CF (Change Factor) : Statistical downscaling   Study period :  Historical (1976-2005)  2025s (2011-2040), 2055s (2041-2070), 2085s (2071-2100)

12. Reservoir Water balance t: time S: Reservoir storage I: Inflow (using tank model) P: Precipitation on reservoir surface R: Release (using FAO Modified Penman) O: Overflow E: Evaporation on reservoir surface Inflow Ground water inflow Effective storage Dead storage Subsurface infiltration △ storage Surface evaporation Surface precipitation Release seepage Spillway overflow   Water balance model

13. 3. Results and Discussion

14.   Trend of temperature at Suwon weather station (Gyeonggi-province: Central region of Korean Peninsula )  Increasing trends during all periods compared to historical records except RCP2.6_2085s Projection of temperature

15. Projection of rainfall   Trend of rainfall at Suwon weather station  Increasing trends during all periods compared to historical records  RCP8.5_2085s showed largest increase of rainfall (295mm)

16. Regional comparison   Occurrence the dead storage ProvincesReservoirsHistorical RCP_2.6RCP_8.5 2025s2055s2085s2025s2055s2085s Gyeonggi Docheok (A)810655419 Jungri (B)1115956721 Gangwon Gungchon-221-14 Ucheon------- Chungcheongbuk Geumseong26431414 Chupungnyeong----5-1 Chungcheongnam Sinhyu-31--1- Gusu77708358816270 Jeollabuk Gongan32----4 Songgok16 12913911 Jeollanam Deungam31----2 Cheonjeong22231718201821 Gyeongsangbuk Samjeong134-823 Jeomgok------- Gyeongsangnam Daecheon----4-- Segajeong----2--

17. Analysis of water supply capability (1)   Reservoir A (case 1) : RCP2.6 scenario Transplanting period Average 10 th percentile

18. Analysis of water supply capability (2)   Reservoir A (case 1) : RCP8.5 scenario Transplanting period Average 10 th percentile

19. Analysis of water supply capability (3)   Reservoir B (case 2) : RCP2.6 scenario Transplanting period Average 10 th percentile

20. Analysis of water supply capability (4)   Reservoir B (case 2) : RCP8.5 scenario Transplanting period Average 10 th percentile

21. 4. Conclusions

22. ConclusionsConclusions   This study analyzed the water supply capability of agricultural reservoirs about 10-year design drought return period for RCP scenarios   Climate change causes  Increasing rainfall amount and temperature  Altering agricultural reservoirs water balance  Demonstrating that rainfall variation in May-June possibly causes irrigation shortage after transplanting period, especially for RCP 2.6_2025s and RCP 8.5_2085s   Future study  Analysis about the reservoir size and demand area and return periods in detail

23. Thank you! Irrigation Australia/7 th Asian Regional Conference

24.   RCP (Representative Concentration Pathways)  Greenhouse gas concentrations were determined by radiation that human activity effected on the atmosphere (IPCC AR5)  ‘representative’: one of several different scenarios that have similar radiative forcing and emissions characteristics  ‘pathways’: time-dependent projections of atmospheric greenhouse gas (GHG) concentrations Climate change data RCPDescriptionPathway shapeSRES RCP 8.5 Rising radiative forcing pathway leading to 8.5 W/m 2 (~1370 ppm CO2 eq) by 2100. RisingA2- A1FA1 RCP 6.0 Stabilization without overshoot pathway to 6 W/m 2 (~850 ppm CO2 eq) at stabilization after 2100 Stabilization without Overshoot A1B RCP 4.5 Stabilization without overshoot pathway to 4.5 W/m 2 (~650 ppm CO2 eq) at stabilization after 2100 Stabilization without Overshoot B1 RCP 2.6 Peak in radiative forcing at ~3 W/m 2 (~490 ppm CO2 eq) before 2100 and then decline (the selected pathway declines to 2.6 W/m 2 by 2100). Peak and decline-

25.   CanESM2(The second generation Canadian Earth System Model)  Fourth version of CCCma (Canadian Center for Climate Modeling and Analysis)  To the IPCC AR4 Under consideration in CMIP5(Coupled Model Intercomparison Project Phase 5)  Study period : Historical (1976-2005) 2025s (2011-2040) 2055s (2041-2070) 2085s (2071-2100) Climate data (Arora et al, 2011)

26. Tank model   Tank model  Typical conceptual rainfall-runoff model  Simulate daily inflow in each reservoir for a data scarce watershed - First Tank : Concept of Surface flow - Second Tank : Concept of Inter flow - Third Tank : Concept of Base flow   Factors  Watershed area  Area of each land use type in watershed

27. Analysis of water supply capability (1)   Reservoir A (case 1) : RCP8.5 scenario 10 th percentile