Impact of Climate Change on River Discharge in Namsane River Basin Lao PDR Ketsana XAIYASARN (Mr) Lao NaBonal Mekong CommiDee Secretariat, Lao PDR
IntroducBon o o o o o Lao PDR situate in hearth of Indochina Peninsular Bordered by China to the North, Viet Nam to the East, Cambodia to the South, and Thailand andmyanmar (Burma) to the West and Northwest respecbvely Lay in Mekong River Basin with annual average 35% of the annual flow of the whole Mekong river The Lao PDR has a tropical climate, which is influenced by the southeast monsoon which causes significant rainfall and high humidity The average annual rainfall is about 1300 3 000 mm with average temp 20-27 C
Study Area o Nam Sane river is one the tributaries of the Mekong River o Located in middle part of of LAO PDR o Catchment area of 2,100 km 2, 157 km length o Annual mean temperature ranges from 8 C to 34 C o Annual rainfall range 1,500 3,100 mm and annual average of discharge in Meungkao StaBon is 130 m 3 /s
Some Experience from CC in Laos 1) Water shortage in dry season but too much water in rainy season 2) Many development projected planned in Namsane (3 Hydropower Projects and 50,000 Ha of irrigation planned in Namsane river basin) Flood in Namsane River Basin 05 Aug2015 Water Shortage in Namsane River Basin Feb 2015
Current SituaBon of Namsane River Basin 1400 1200 1000 Discharge (m 3 /s) 800 600 400 1997 2000 2005 2012 200 0 1 9 17 25 33 41 49 57 65 73 81 89 97 105 113 121 129 137 145 153 161 169 177 185 193 201 209 217 225 233 241 249 257 265 273 281 289 297 305 313 321 329 337 345 353 361 Namsane Hydrograph
ObjecBve 1. To analyze climate change condibon in Namsane river basin from 2020 to 2040 2. To assess the impact of climate change on discharge in Namsane river basin towards 2040.
Climate Change Data PreparaBon Climate Data Distribution Systtem GCM: ECHAM 4 Extract Data (Achieve File; txt file) SEA START Analysis Tools Using MS. Excel to Analyse Data ReArrange Data for MS. Excel Down Scale Data Choosing Position Analys Data Rename the FIle Bias Correction (delta change) Data PreparaBon (*.dbf) Input to SWAT Model
Data Input
Methodology Soil and Water Assessment Tool (SWAT) model has been applied to assess the discharge in the study area South East Asia SysTem for Analysis, Research and Training (SEA START) analysis tool has been applied to interpret climate data from ECHAM4 MS. Excel applied for data analysis and chart production
Result on Temperature ProjecBon The future temperature in Namsane River basin will increase slightly towards 2040. Temp ( c) 3 2 1 Temp in upper basin Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean(BL) 16.03 17.97 21.05 22.35 23.30 23.53 23.25 23.01 22.05 20.58 17.63 15.18 Mean (A2) 15.25 18.36 22.98 18.5 25.51 25.51 22.7 21.16 21.17 20.09 17.5 15.42 Mean(B2) 14.89 18.39 22.65 18.56 25.75 25.11 23.18 21.27 21.35 20.14 17.49 15.14 The lower basin of basin will hoder around 1.81 C and the upper basin of the basin will increase around 2.51 C. Temp ( c) 4 3 2 1 Temp in lower basin Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean(BL) 22.69 24.96 26.85 28.70 28.34 27.97 27.66 27.58 27.50 27.12 25.22 23.05 Mean(A2) 22.32 25.43 30.84 25.55 32.84 32.09 28.01 26.77 27.39 27.08 24.90 22.72 Mean(B2) 21.9125.7730.3825.9433.1631.5228.6426.7927.3326.8124.6622.24 10
Future Trend of Rainfall Result on Rainfall ProjecBon Rainfall will increase around 1.5-5% or around 44-134 mm. Future rainfall will decrease in July (rainy season) but will increase in August and September and October Wet season rainfall will increase around 66 Dry season the rain will less than the baseline condibon but no later than 10 mm Rainfall (mm) Rain (mm) 90 80 70 60 50 40 30 20 10 2520 2500 2480 2460 2440 2420 2400 2380 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec BL 12.43 28.09 58.49 127.9 398.9 666.7 785.3 558.4 351.5 51.68 16.85 1.13 A2 10.24 27.31 58.59 128.7 394.9 707.3 715.6 605.2 425.1 93.33 17.82 0.59 B2 4.30 19.57 52.84 130.1 410.1 669.2 665.4 632.4 492.3 83.97 29.00 2.26 Changing Rain in Wet Season BL A2 B2 Rain Rain (mm) Changing Rain in Dry Season 265 264 263 262 261 260 259 258 257 256 255 BL A2 B2 Rain
Projected Change on Mean Monthly Discharge Discharge will decrease in January and February but increased from March to December. The peak of the discharge will shij from July to August and slightly decrease in September to December Discharge (m 3 /s) 450 400 350 300 250 200 150 100 50 Mean Monthly discharge at Meung Kao StaDon 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec BL 21.619 17.246 13.990 17.163 57.310 191.64 392.63 392.84 275.97 100.11 48.739 31.114 4 5 1 8 1 8 4 1 1 3 8 A2 13.511 11.380 21.112 45.879 116.52 269.70 352.05 389.42 328.05 201.29 87.867 35.668 9 8 7 7 9 5 3 6 2 5 B2 15.675 9.6522 15.747 41.695 121.95 250.20 338.07 405.01 368.03 227.19 98.931 40.197 5 2 2 2 4 2 3 8 3 1 7 4 130.03 2
CC Impact on Wet Season A2 Scenario, Discharge will increase at all basin of the basin but decrease in 2030 in upper basin B2 Scenario discharge will increase in 2020 and 2040, but will decrease in middle basin, lower and mouth of the basin in 2025 and 2035. % change % change 8 6 4 2-2 6 5 4 3 2 1-1 - 2 Upper basin (wet season) A2 B2 2020 2025 2030 2035 2040 Lower basin (wet season) A2 B2 2020 2025 2030 2035 2040 % change Middle basin (wet season) 6 5 A2 B2 4 3 2 1-1 - 2 2020 2025 2030 2035 2040 Outlet (wet season) 6 5 A2 B2 % change 4 3 2 1-1 - 2 2020 2025 2030 2035 2040
CC Impact on Dry Season A2 scenario the discharge will increase >100% in 2030 and 2040 (Upper basin), and 2040 (upper, middle and lower part) and decrease in 2020 and 2030 at mouth of the basin. B2 Scenario the discharge will decrease in 2025 and 2030 (outlet). % change % change Upper basin (dry season) A2 B2 20 15 10 5 2020 2025 2030 2035 2040 Lower basin (dry season) A2 B2 20 15 10 5 2020 2025 2030 2035 2040 % change % change 18 16 14 12 10 8 6 4 2 6 5 4 3 2 1-1 - 2-3 Middle basin (dry season) A2 B2 2020 2025 2030 2035 2040 Outlet (dry season) A2 B2 2020 2025 2030 2035 2040
Conclusion The upper part of the basin will be increased up to 2.51 C and 1.81 C in lower part of the basin respecbvely. Rainfall will change lidle around 1.5% - 5% of the total rainfall and July (rainy season) will decrease and will increase in August and September Discharge will also increase in wet and dry season (weder in wet and weder in dry season) Discharge in July will decrease but discharge will increase in August and September (rainy season) Delay in flood season shij from July to August or September
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