, 57 213 2 WATER RESOURCES PROJECTION AT THE PASAK RIVER BASIN IN THAILAND UNDER A CHANGING CLIMATE 1 2 3 4 5 Y. TACHIKAWA, Y. FUJITA, M. SHIIBA, K. YOROZU and S. KIM 1 ( ) ( 615-854 C1) 2 ( ) J-POWER Generation (Thailand) Co., Ltd. 3 ( 615-854 C1) 4 ( ) ( 615-854 C1) 5 ( ) ( 615-854 C1) A change of water resources in the late 21st century at the Pasak River basin in Thailand is analyzed using a distributed rainfall-runoff model and a rainfall and evapotranspiration output projectedby MRI- GCM3.1S. The main findings are as follows: a projectedmean annual inflow tothepasak Dam reservoir for the near future andthe late 21st century experiments decrease by 3.8% and3.5% comparedwith the present climate experiment; a projectedmean monthly inflow using the output of the late 21st century experiment decreases except from July to September; andto maintain a present dam outflow is difficult in the future under a scenario of the same water demand. Key Words: Climate change, river discharge projection, Pasak river, Thailand, water resources 1. 1) 2, 3, 4) 5, 6) 211 21 (16,291km 2 ) 7) 2. -1 14,52km 2 9 4,86m 36.5m 1994 1999 3. (1) A1B MRI-AGCM3.1S 2km 1 3 ffl 1979 1 23 12 : ffl 215 1 239 12 : ffl 275 1 299 12 : 21-2 APHRODITE 8)
Chao Phraya River basin Pasak River basin -4 25 981mm 986mm 21 127mm.51% 21 4.73% ( ) 21 197mm 177mm 172mm.17.15.14 Pasak Dam 4. 1 2 4 km -1 (HydroSHEDS ) 1979 23 1178mm APHRODITE 953mm 3 6 2 28 117mm -3 25 1163.1mm 21 1199.1mm 1.26% 21 1.8% (2) APHRODITE GAME-T2 9) 1981 1999.1.2 8 9 (1) 1, 11) HydroSHEDS 12) 5m GeoHyMoS 13) HydroSHEDS 13) 14) (2) APHRODITE (1979 1 23 12 ) 1987 1 1 1987 12 31 1 APHRODITE Precipitation [mm] 25 2 15 1 5 Observed data in APHRODITE Precipitation [mm] 16 14 12 1 8 6 4 2 Evapotranspiration [mm] 12 1 8 6 4 2 2 4 6 8 1 12 198 2 22 24 26 28 21 Year 198 2 22 24 26 28 21 Year -2 APHRODITE -3-4
Discharge [m 3 /sec] 16 14 12 1 8 6 4 2 simulated discharge observed discharge 1/1 2/1 3/1 4/1 5/1 6/1 7/1 8/1 9/1 1/1 11/1 12/1 Date 1 2 3 4 5 6 7 8 9 1-5 1987 1-1 n (m 1=3 s) k a (m/s) d s (m) d c (m) fi.6.8 1..4 12-2 Year R Q p N s R Q T e R v 1981 126 328.81 1.13 2 1.13 1982 947 795.83 1.5-8.92 1983 928 851.92.79 4 1. 1984 973 576.82.7-6.87 1985 16 787.85 1.6-7.96 1986 829 174.28 1.68 27 1.7 1987 Λ 99 996.95.99-7.99 1988 937 419.53.65-9.97 1989 867 181 -.15 1.55 126 1.27 199 928 731.82.63-1.88 1991 874 658.72.68-3.71 1992 733 294.74.73-14.97 1993 735 237.78.55 16.86 Λ :, R : APHRODITE (mm), Q p : (m 3 /s), N s : Nash, R Q : ( / ) (%), T e : ( ) (day), R v : ( / ) (%) -5-1.3m 1=3 s -2 APHRODITE 1986 1989 2m 3 /s Nash Nash.7 1.±.1 Precipitation [mm] ly mean Discharge [m 3 /sec] 7 6 5 4 3 2 1 1 2 Simulated inflow using rainfall and evapotranspiration in present-day climate experiment Simulated inflow using APHRODITE rainfall and evapotranspiration in present-day climate experiment Observed inflow 3 4 5 6 7-6 APHRODITE Daily mean discharge [m 3 /sec] 9 8 7 6 5 4 3 2 1 1/1 2/1 standard deviation standard deviation standard deviation 3/1 4/1 5/1 6/1 7/1 8/1 9/1 1/1 11/1 12/1 Date -7 (3) APHRODITE 1979 23 25 25 25-6 APHRODITE 5 1-2 APHRODITE (4) 21 25-7 25 7 8 21 9 1 21 7 8 9 1 8 9 1 11 12
Change ratio 1.2 1.8.6.4.2 1 8 6 4 2 96 Upper rule curve 96 86 Lower rule curve 82 75 7 7 65 617 67 55 6 5 4 37 4 35 25 25 22 25 25 2 Montly loss (MCM) 5 4 3 2 1 1 2 3 4 5 6 7 8 9 1 11 12 1 2 3 4 5 6 7 8 9 1 11 12 1-1 1 2 3 4 5 6 7 8 9 1 11 12-8 -9-1 (1999 21 ) -8 25 21 7 8 25 3.8% 21 3.5% 5. ( -9 ) (1) i j S i;j I i;j O i;j L i;j S i;j = I i;j O i;j L i;j (1) L i;j 21 1 29 12 L i;j -1 L i;j 3 24.4MCM(24.4 m 3 ) ( 182.59km 2 ) 1 4.3mm/day 3 2.6mm/day 92.5km 2 2.6mm/day 1mm/day 1.8mm/day 4.4mm/day 15 1 5-5 -1 Observed storage 1 13 25 37 49 61 73 85 97 19-11 ( ) (2) a) i j Ii;j P 21 ( -8 ) I N i;j ;IF i;j r N;P j = Ii;j N =IP i;j ; rf;p j = Ii;j F =IP i;j ; j =1; ; 12 Ii;j O ;i = 21; ; 29 21 ^I i;j N ; ^I i;j F ^I i;j N = rn;p j Ii;j O ; ^IF i;j = r F;P j Ii;j O j =1; ; 12 (2) (1) 9 (18 ) -11 ( ) 3 b) 9
4 3 2 1-1 -2-3 -4-5 1 13 25 37 49 61 73 85 97 19 121 133 145 157 169 181 193 25 217 229 241 253 265 277 289-12 ( ) -3 ( ) a b c a b c 6.42.62-18.3 12 -.23 -. 69.1 7.92.46-14.4 1.68.6 31.1 8 1.3 -.12-32.1 2 1.76 -.6 12.1 9.91.5-498.7 3 1.8 -.16 168.6 1.91.59-559.7 4 -.9.39-66.9 11.81.48-399. 5.4.23 9.3 Ii;j P Ii;j O r O;P j = Ii;j O =IP i;j ; j =1; ; 12 ~I P i;j = ro;p j I P i;j ; ~ I N i;j = r O;P j I N i;j ; ~ I F i;j = r O;P j I F i;j (3) i =1; ; 25 25-12 21 8 96MCM c) 2 i j O i;j I i;j S i;j O i;j = a j I i;j + b j S i;j + c j (4) 1999 21 a j b j c j O i;j I i;j S i;j MCM a j b j c j MCM ly discharge (MCM) 18 Simulated discharge 16 Observed discharge 14 12 1 8 6 4 2 1 13 25 37 49 61 73 85 97 19 (a) 12 Simulated storage Observed storage 1 8 6 4 2 1 13 25 37 49 61 73 85 97 19 (b) -13 (21 29 ) -3 7 11 a i 1. 12 3 c i -13 (4) b) (4) -14 25 2 (4) -15 1 21 4.8% 6.1%
9 8 7 Present-day climate experiment Near future climate experiment Future climate experiment (A)2324689 6 5 4 3 2 1 1 13 25 37 49 61 73 85 97 19 121 133 145 157 169 181 193 25 217 229 241 253 265 277 289 31-14 ( ) ly mean outflow (MCM) 6 5 4 3 2 1 Observed outflow 1 2 3 4 5 6 7 8 9 1 11 12-15 6. 7) 21 21 4.8% 6.1% 21 1) S. Kusunoki, R. Mizuta, and M. Matsueda : Future changes in the East Asian rain bandprojected by global atmospheric models with 2-km and 6- km gridsize, Climate Dynamics, 37(11-12), pp. 2481-2493, 211. 2),,,,, :,, 67(1), pp. 1-15, 211. 3),,,,, :,, 52B, pp. 573-586, 29. 4) P. A. Jaranilla-Sanchez et al. : Integrated modeling of climate change impacts in the Yoshino River basin, Japan for basin management planning, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 68(4), pp. I 133-I 138, 212. 5) T. Nakaegawa, C. Wachana andkakushin Team-3 Modeling Group: First impact assessment of hydrological cycle in the Tana River Basin, Kenya, under a changing climate in the late 21st Century, Hydrological Research Letters, 6, pp. 29-34, 212. 6) T. Ogata et al. : Past andfuture hydrological simulations of Chao Phraya river basin, Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 68(4), pp. I 97-I 12, 212. 7) P. B. Hunumumbura and Y. Tachikawa: River discharge projection under climate change in the Chao Phraya River Basin, Thailand, using the MRI- GCM3.1S dataset, Journal of the Meteorological Society of Japan, 9A, pp. 137-15, 212. 8) : APHRODITE's Water Resources, http:// www.chikyu.ac.jp/precip/ ( 212/9/3). 9) : GAME-T2 Data Center, http://hydro.iis.u-tokyo.ac.jp/game- T/GAIN-T/index.html ( 212/9/3). 1),,, :,, 621/II-47, pp. 1-9, 1999. 11),,, :,, 691/II-57, pp. 43-52, 21. 12) USGS : HydroSHEDS, http://hydrosheds.cr.usgs. gov/ ( : 212 9 3 ). 13) :, http://hywr.kuciv.kyoto-u.ac.jp/geohymos/geohy mos.html ( : 212 9 3 ). 14),, :,, 48, pp. 7-12, 24. 212.9.3