Downstream Hydrological Impacts of Hydropower Development in the Upper Mekong Basin


The Mekong River Basin in Southeast Asia is experiencing extensive hydropower development. Concerns have been raised about the consequences of the development for the ecosystems, livelihoods and food security in the region. The largest planned hydropower dam cascade in the basin, the Lancang-Jiang cascade, is currently under construction and already partly built into the Upper Mekong Basin, China. In this paper we assess the impact of the Lancang-Jiang cascade on downstream hydrology by using a combination of a hydrological model and a reservoir cascade optimization model. The hydrological changes were quantified in detail at the Chiang Saen gauging station in Thailand, the first gauge station downstream from the cascade, and in lesser detail at four other downstream locations in the Mekong mainstream. We found that on average the Lancang-Jiang cascade increased the December–May discharge by 34–155 % and decreased the July–September discharge by 29–36 % at Chiang Saen. Furthermore, the Lancang-Jiang cascade reduced (increased) the range of hydrological variability during the wet season (dry season) months. The dry season hydrological changes were significant also in all downstream gauging stations, even as far as Kratie in Cambodia. Thus the Mekong’s hydrological regime has been significantly altered by the Lancang-Jiang cascade, but what the consequences are for ecosystems and livelihoods, needs further study.

This is a preview of subscription content, access via your institution.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7


  1. Adamson P (2001) The Potential impacts of hydropower developments in Yunnan on the hydrology of the lower Mekong. International Water Power and Dam Construction 53:16–21

    Google Scholar 

  2. ADB (2004) Cumulative impact analysis and Nam Theun 2 contributions: Final report. Prepared by NORPLAN and EcoLao for Asian Development Bank (ADB). Accessed 16 September 2010

  3. ADB (2008) Lao People’s Democratic Republic: Preparing the Cumulative Impact Assessment for the Nam Ngum 3 hydropower project. Prepared by Vattenfall Power Consultant AB in association with Ramboll Natura AB and Earth Systems Lao for Asian Development Bank (ADB). Accessed January 2012

  4. Bunn S, Arthington A (2002) Basic principles and ecological consequences of altered flow regimes for aquatic biodiversity. Environ Manag 30:492–507

    Article  Google Scholar 

  5. Delgado J, Apel H, Merz B (2010) Flood trends and variability in the Mekong river. Hydrol Earth Syst Sci 14:407–418

    Article  Google Scholar 

  6. Delgado J, Merz B, Apel H (2012) Climate-flood link for the lower Mekong River. Hydrol Earth Syst Sci 16:1533–1541

  7. Dingman S (2002) Physical hydrology, 2nd edn. Waveland Press, Illinois, 600

    Google Scholar 

  8. Driessen P, Decker J, Spaargaren O, Nachtergaele F (eds.) (2001) Lecture notes on the major soils of the world. Food and Agriculture Organization of United Nations (FAO)

  9. Dugan P (2008) Mainstream dams as barriers to fish migration: international learning and implications for the Mekong. Catch Culture 14:9–15

    Google Scholar 

  10. Dugan P, Barlow C, Agostinho A et al (2010) Fish migration, dams, and loss of ecosystem services in the Mekong Basin. Ambio 39:344–348

    Article  Google Scholar 

  11. FAO (2003) WRB map of world soil resources. Food and Agriculture Organization of United Nations (FAO), Land and Water Development Division.

  12. GLC2000 (2003) Global Land Cover 2000 database. European Commission, Joint Research Centre

  13. Grumbine R, Xu J (2011) Mekong hydropower development. Science 322:178–179

    Article  Google Scholar 

  14. Grumbine R, Dore J, Xu J (2012) Mekong Hydropower: drivers of change and governance challenges. Front Ecol Environ 10:91–98

    Article  Google Scholar 

  15. Hoanh C, Jirayoot K, Lacombe G, Srinetr V (2010) Impacts of climate change and development on the Mekong flow regime, First assessment - 2009. MRC Technical Paper No. 29 Mekong River Commission, Vientiane, Lao PDR. Accessed January 2012

  16. Hortle K (2007) Consumption and the yield of fish and other aquatic animals from the lower Mekong Basin. Mekong River Commission Technical Paper 16, Mekong River Commission, Vientiane. Accessed January 2012

  17. HydroChina (2010) Map of planned and existing hydropower projects. Accessed 16 September 2010

  18. ICEM (2010) MRC Strategic Environmental Assessment (SEA) of hydropower on the Mekong Mainstream. Hanoi, Viet Nam. Accessed January 2012

  19. Jarvis A, Reuter H, Nelson A, Guevara E (2008) Hole-filled SRTM for the globe Version 4. CGIAR-CSI SRTM 90 m Database

  20. Johnston R, Kummu M (2012) Hydrological modelling in the Mekong Basin: a review. Water Resour Manag 26:429–455

    Article  Google Scholar 

  21. Junk W, Wantzen K (2004) The flood pulse concept: New aspects, approaches and applications – An update. In: Welcomme R, Petr T (eds.) Proceeding of international symposium on the management of large river for fisheries. RAP Publications 2004716, FAO, Bangkok 2:117–140

  22. Junk W, Bayley P, Sparks R (1989) The flood pulse concept in river-floodplain systems. In: Dodge D (ed.) Proceedings of the international large river symposium (LARS). Canadian Special Publication of Fisheries and Aquatic Sciences 106:110–127

  23. Junk W, Brown M, Campbell I et al (2006) The comparative biodiversity of seven globally important wetlands: a synthesis. Aquat Sci 68:400–414

    Article  Google Scholar 

  24. Keskinen M, Kummu M (2010) Impact assessment in the Mekong: review of strategic environmental assessment (SEA) & cumulative impact assessment (CIA). Water & Development Publications, Aalto University. TKK-WD-08. 48 p. Accessed January 2012

  25. Keskinen M, Chinvanno S, Kummu M, Nuorteva P, Snidvongs A, Varis O, Västilä K (2010) Climate change and water resources in the Lower Mekong River Basin: putting adaptation into the context. J Water Clim Change 1:103–117

    Article  Google Scholar 

  26. Keskinen M, Kummu M, Käkönen M, Varis O (2012) Mekong at the crossroads: next steps for impact assessment of large dams. Ambio 41:319–324

    Article  Google Scholar 

  27. Kingston D, Thompson J, Kite G (2011) Uncertainty in climate change projections of discharge for the Mekong River Basin. Hydrol Earth Syst Sci 15:1459–1471

    Article  Google Scholar 

  28. Koponen J, Lauri H, Veijalainen N, Sarkkula J (2010) HBV and IWRM Watershed Modelling User Guide. MRC Information and Knowledge management Programme, DMS – Detailed Modelling Support for the MRC Project. Accessed January 2012

  29. Kummu M (2008) Spatio-temporal scales of hydrological impact assessment in large river basins: the Mekong case. PhD Thesis, Water Resources Research Unit, Helsinki University of Technology. 92+ app. p 112

  30. Kummu M, Sarkkula J (2008) Impact of Mekong River flow alteration on Tonle Sap flood pulse. Ambio 3:185–192

    Article  Google Scholar 

  31. Kummu M, Varis O (2007) Sediment-related impacts due to upstream reservoir trapping, the Lower Mekong River. Geomorphology 85:275–293

    Article  Google Scholar 

  32. Kummu M, Lu XX, Wang JJ, Varis O (2010) Basin-wide sediment trapping efficiency of emerging reservoirs along the Mekong. Geomorphology 119:181–197

    Article  Google Scholar 

  33. Labadie J (2003) Generalized dynamic programming package: CSUDP. Documentation and user guide, version 2.44. Accessed January 2012

  34. Labadie J (2004) Optimal operation of multireservoir systems: state of the art review. J Water Resour Plann Manag 130:93–11

    Article  Google Scholar 

  35. Lamberts D (2008) Little impact, much damage: the consequences of Mekong River flow alterations for the Tonle Sap ecosystem. In: Kummu M, Keskinen M, Varis O (eds.) Modern myths of the Mekong. Water & Development Publications, Helsinki University of Technology, pp. 3–18

  36. MRC (2005) Overview of the hydrology of the Mekong Basin. Mekong River Commission (MRC), Vientiane, Lao PDR

  37. MRC (2009a) Economic, environmental and social impact assessment of basin-wide water resources development scenarios, Assessment methodology. Mekong River Commission (MRC) technical note, Vientiane Lao PDR. Accessed January 2012

  38. MRC (2009b) Hydropower dam database. Mekong River Commission (MRC), Vientiane Lao PDR.

  39. MRC (2009c) Mekong river basin 1:50’000 vector data. Mekong River Commission (MRC), Vientiane Lao PDR

  40. MRC (2010) State of the basin report 2010. Mekong River Commission (MRC), Vientiane, Lao PDR. p 232

  41. MRC (2011) Assessment of basin-wide development scenarios, Basin Development Plan Programme, Phase 2. Mekong River Commission (MRC), Vientiane, Lao PDR Accessed January 2012

  42. MRCS/WUP-FIN (2003) Modelling Tonle Sap for environmental impact assessment and management support. Final report, WUP-FIN Phase I, Mekong River Commission and Finnish Environment Institute consultancy consortium, Phnom Penh. Accessed January 2012

  43. NASA (2010) Tropical rainfall measuring mission (TRMM). NASA, Goddard Space Flight Center.

  44. NCDC (2010) Global Surface Summary of the Day (GSOD). US National Climatic Data Center.

  45. Nilsson C, Berggren K (2000) Alterations of riparian ecosystems caused by river regulation. BioScience 50:783–792

    Article  Google Scholar 

  46. Nilsson C, Reidy C, Dynesius M, Revenge C (2005) Fragmentation and flow regulation of the world’s large river systems. Science 308:405–408

    Article  Google Scholar 

  47. Peel M, Finlayson B, McMahon T (2007) Updated world map of the Köppen-Geiger climate classification. Hydrol Earth Syst Sci 11:1633–1644

    Article  Google Scholar 

  48. Qiu J (2010) China drought highlights future climate threats. Nature 465:142–143

    Article  Google Scholar 

  49. Rani D, Moreira M (2010) Simulation-optimization modeling: a survey and potential application in reservoir systems operation. Water Resour Manag 24:1107–1138

    Article  Google Scholar 

  50. Sarkkula J, Keskinen M, Koponen J, Kummu M, Richey J, Varis O (2009) Hydropower in the Mekong region: what are the likely impacts upon fisheries? In: Molle F, Foran T, Käkönen M (eds) Contested waterscapes in the Mekong region - Hydropower, livelihoods and governance. Earthscan. pp. 227–249

  51. Sarkkula J, Koponen J, Lauri H, Virtanen M (2010) IWRM modelling report. Detailed Modelling Support (DMS), Information and Knowledge Management Programme, Mekong River Commission. Accessed January 2012.

  52. Saxton K, Rawls W (2006) Soil water characteristic estimates by texture and organic matter for hydrological solutions. Soil Sci Soc Am J 70:1569–1578

    Article  Google Scholar 

  53. Stone R (2010) Severe drought puts spotlight on Chinese dams. Science 327:1311

    Article  Google Scholar 

  54. Stone R (2011) Mayhem in the Mekong. Science 333:814–818

    Article  Google Scholar 

  55. Surian N (1999) Channel changes due to river regulation: the case of Piave River, Italy. Earth Surf Process Landforms 24:1135–1151

    Article  Google Scholar 

  56. Västilä K, Kummu M, Sangmanee C, Chinvanno S (2010) Modelling climate change impacts on the flood pulse in the Lower Mekong floodplains. J Water Clim Change 1:67–86

    Article  Google Scholar 

  57. World Bank (2004) Modelled observations on development scenarios in the Lower Mekong Basin, Mekong Regional Water Resources Assistance Strategy. Prepared for the World Bank with Mekong River Commission cooperation. p. 142. Accessed June 2012

  58. WUP-FIN (2008) Hydrological, environmental and socio-economic,modelling tools for the Lower Mekong Basin impact assessment. WUP-FIN Phase II, Mekong River Commission and Finnish Environment Institute consultancy consortium, Accessed January 2012

  59. Yi J, Labadie J, Stitt S (2003) Dynamic optimal unit commitment and loading in hydropower systems. J Water Resour Plann Manag 129:388–398

    Article  Google Scholar 

Download references


The authors would like to thank the Mekong River Commission for providing the discharge data for the study. The authors are grateful to Prof. Olli Varis, Dr. Marko Keskinen, Aura Salmivaara and Mirja Kattelus for their support. Timo Räsänen received funding from the RYM-TO Graduate School and Maa- ja Vesitekniikan Tuki ry. and Matti Kummu received funding from the postdoctoral funds of Aalto University. The research was also supported by Academy of Finland (project 133748).

Author information



Corresponding author

Correspondence to Timo A. Räsänen.

Electronic supplementary material

Below is the link to the electronic supplementary material.


(PDF 536 KB)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Räsänen, T.A., Koponen, J., Lauri, H. et al. Downstream Hydrological Impacts of Hydropower Development in the Upper Mekong Basin. Water Resour Manage 26, 3495–3513 (2012).

Download citation


  • Hydrological impact assessment
  • Hydrological modelling
  • Dynamic programming
  • Hydropower operation
  • The Mekong Basin
  • Yunnan