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

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

1. Introduction

  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

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

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)

  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

2. Methodology

Flow chart (2.6, 8.5)

  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 Sinhyu Gusu3228 …………

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 ( )  2025s ( ), 2055s ( ), 2085s ( )

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

3. Results and Discussion

  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

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)

Regional comparison   Occurrence the dead storage ProvincesReservoirsHistorical RCP_2.6RCP_ s2055s2085s2025s2055s2085s Gyeonggi Docheok (A) Jungri (B) Gangwon Gungchon Ucheon Chungcheongbuk Geumseong Chupungnyeong Chungcheongnam Sinhyu Gusu Jeollabuk Gongan Songgok Jeollanam Deungam Cheonjeong Gyeongsangbuk Samjeong Jeomgok Gyeongsangnam Daecheon Segajeong

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

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

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

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

4. Conclusions

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

Thank you! Irrigation Australia/7 th Asian Regional Conference

  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 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-

  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 ( ) 2025s ( ) 2055s ( ) 2085s ( ) Climate data (Arora et al, 2011)

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

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