1 Module 2 Mekong Resources, Benefits to people, and Planning Issues session 1 : The Mekong and its water resources

2 Module Objective Participants can identify Mekong water/ relate resources, current benefits to basin peoples, potentials for future development, and able to define key issues for planning water resources development.

3 “..the Mekong River Basin and the related natural resources and environment are natural assets of immense value…” 1995 Agreement

4 China Myanmar Laos Thailand Cambodia Viet Nam Discharge: 475 km 3 / year Area: 795,000 km 2 Mekong River Basin Upper Basin Lower Basin Murray-Darling Discharge: 12.6 km 3 / year Area: 1,073,000 km 2

5 Mekong River Basin Upper Mekong Basin (UMB) 18 % of total flow (China 16% & Myanmar 2%) Lower Mekong Basin (LMB) 625,000 km2 82 % total flows Cambodia – 18% Lao PDR – 35% Thailand – 18% Viet Nam – 11%

6 MRB water resource Description ChinaMyaLaoThaiCamV/NTotal Catchment (Km 2 ) 165,00024,000202,000184,000155,00065,000795,000 % of Basin 22%3%25%23%19%8% % of country 4%97%36%86%20% Average Flow (m 3 /s) 2, ,2702,5602,8601,66015,060 Percentage 16%2%35%18% 11%

7 Main regions in the Mekong

8 Main regions Upper Mekong Basin Mekong River Basin For most of its length, it flows Through narrow valleys in the Mountain in China. Upper Basin is narrow, with few tributaries And gives 18% of the total flow

9 Manwan and Dachaoshan dams, Feb km

10 Main regions Upper Mekong Basin Lower Mekong basin Highlands Mekong River Basin

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13 Mekong River Basin Main regions Upper Mekong Basin Lower Mekong Highlands Central/Isan Plateau

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15 Mekong River Basin Main regions Upper Mekong Basin Highlands Central / Isan Plateau Cambodian plain and Great Lake

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17 Mekong River Basin Main regions Upper Mekong Basin Highlands Isan Plateau Cambodian plain and Great Lake Delta

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19 Flow regime

20 Hydrological Regime Hydro. Regime depends on climatic conditions of wet and dry seasons. High water period from Sept – Nov; Low flow period from Feb. – April. Flood season in mainstream and tributaries, from June-July to Nov-Dec accounts for 85-90% of total annual water volume. Peak month of Sept accounts for 20-30% of annual flow.

21 Monsoonal climate dry season November to May wet season June to October 35% 20% Contribution to Mekong flows 16%Climate

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23 The % contribution of flow from China to average monthly flow at … % Flow from China dominates the dry season hydrology of the Lower Mekong Flood season flows mostly originate within Laos and the lower basin The % contribution of flow from China to average monthly flow at …

24 20 m River variability Flooding

25 Extent of flooding in LMB

26 Water quality

27 3 commonly identified water quality issues Sediments in the water Salinity ( NE Thai & VN Delta) Eutrophication

28 Trends in total suspended sediment (TSS) in the Lower Mekong Basin Water quality monitoring

29 TSS before and after filling Manwan Dam

30SalinitySalinity In NE Thailand where there has been concerns for salinity, 4 of 5 sites show a decrease most concern sites in Vietnam (9) show also a decrease. EutrophicationEutrophication Mostly a problem in VN delta – 40 sites in the delta show an increase in phosphorus – 31 site in delta show increase in nitrogen – ( both N & P are parameter used eutrophication )

31 Water quality In summary It is quite good when compare with many other international rivers !