Aquatic ecosystem connectivity, ecosystem processes, and watershed integrity under Mekong dam development International Conference on Watershed Management Chiang Mai March 2011 Nikolai Sindorf, WWF Conservation Science Program Trang Dangthuy, WWF Greater Mekong Program Office
Methodology highlights develop a science backed environmental narrative that guides strategic decision making on dam impacts and connectivity, work towards a globally applicable template test river network connectivity visualizations on the Mekong with a focus on dam development propagate an ecosystem inclusive, basin wide, approach to dam development
Approach 1. Aquatic ecosystem classification captures relevant basin wide processes incorporates essential migration triggers open sourced, transparent, replicable 2. Connectivity visualization upstream downstream network analysis allows multiple scales globally replicable to any river system 3. Dam locations location based; not data based configuration of multiple dams, river system perspective 4. Consistent connectivity metric network algorithm; no environmental valuation comparative and scalable not a silver bullet; part of much broader assessment
Elevation RiverKarsts Slope length mainstem > 3,000yes m tributary > 100no m <stream 100 m Classifier Association, representative of: elevation temperature, climate, geography, plateau, upstream / downstream relations, ice / snow, delta / tidal influences slope elevation drop in rivers, erosion / sediment rates, temperature, cascades / rapids, local runoff, vegetation karsts chemistry, caves, endemism river length scale, seasonality, discharge, floodplains / wetlands, river landscape interaction + + + Aquatic ecosystem classification
Ngom Qu Za Qi Zi Qu Qingshuilang Shah Yangbi Nam Loi Nam Mae Ing Nam Tha Nam Ou Nam Khan Nam Chi Nam Mun Tonle Sap Nam Loei Songkhram Stung Sen Nam Ngum Nam Cadinh Se San Se Bang Hien Sre Pok Se Kong Siem Bok Delta Names based on FAO database, 2009, revised
Mekong connectivity schematic (duplicates removed) Nam Ou Nam Ngum Nam Chi, Nam Mun Sekong, Sesan, Srepok Tonle Sap Delta
Connectivity applied to dams and large tributaries Our dam database contains over 50 of the largest or most prominent dams in the basin, and includes hydropower and agricultural dams, it excludes a large amount of smaller, agricultural dams.
Connectivity applied to dams and large tributaries In our initial analysis we found out that the current layout of dams blocks 40 % of the Mekong.
Jinhhong Nam Ou Nam Ngum Songkhram Nam Theun Nam Mun Nam Chi Sedone Sekong Sesan Srepok Tonle Sap
Mekong connectivity schematic Dam locations (manual) Nam Ou Nam Theun Nam Ngum Nam Chi, Nam Mun Tonle Sap Sekong, Sesan, Srepok Delta
Connectivity applied to dams and large tributaries Number of connected ecosystems 1 2 3 4 6 11
Current configuration of the Mekong, with over larger 50 dams Number of connected ecosystems 13 12 11 10 9 8 7 6 5 4 3 2 1 Using a network connectivity algorithm we were able to determine that currently 46 % of ecosystem connectivity is preserved in the Mekong according to this ecosystem classification 0 10 20 30 40 50 60 70 80 90 100 Percentage of total system length (perennial streams)
Impacts on Mekong wide ecosystem connectivity Project name Capacity Impact on connectivity Sayaboury 1,260 MW Nam Theun 2 1,070 MW Se San cascade 1,540 MW
Jinhhong Nam Ou Sayaboury Nam Ngum Songkhram Nam Theun Nam Mun Nam Chi Tonle Sap Sekong Sesan Srepok Plei Krong Yali Se San 3 Se San 3a Se San 4 Se San 4a
Connectivity applied to dams and large tributaries Sayaboury Nam Theun 2 Number of connected ecosystems 1 2 3 4 6 11 Se San Cascade
Sayaboury Nam Theun 2 Number of connected ecosystems 1 2 3 4 6 11 9 Se San Cascade
Impacts on Mekong wide ecosystem connectivity Project name Capacity Impact on connectivity Sayaboury 1,260 MW 5.0 % decrease Nam Theun 2 1,070 MW 0.8 % decrease Se San cascade 1,540 MW 1.2 % decrease Overall ecosystem connectivity is very vulnerable to dam development on the main stem; the reproduction of ecosystem processes in the Mekong is extremely sensitive to the impacts of main stem dams because of its layout; a very long main stem fed by relative short tributaries
Conclusions and recommendations Work towards an open, consistent and reliable database of all existing dams in the Mekong basin, include planned dams Dams on the mainstream have disproportional impacts on the connectivity o f the ecosystems, compared to tributary dams Incorporate ecosystem processes connectivity as a guideline in basin wide dam planning
Thank you The methodology, analysis, and maps in this presentation are under copyright of WWF 2011, and need to be properly referenced and acknowledged when being reused. Please contact us at: trang.dangthuy@wwfgreatermekong.org nikolai.sindorf@wwfus.org http://www.worldwildlife.org/science/projects/freshwater/freshwater.html http://wwf.panda.org/what_we_do/where_we_work/greatermekong/