MEKONG BASIN RESEARCH (SE-ASIA)

Climate

The Tibetan plateau has been identified as a tipping point for climate change impacts as accelerated glacier and snow melt causes a positive feedback accelerating the melting process by the enlarged dark rocky ground attracting more heat.
During the low flow season in April and May, 75-95% of the Mekong runoff in Vientiane originates in Tibet and during the peak flow months from July to September over 50%. Changes in snow melt driven hydrology in Tibet will hence significantly impact downstream hydrology and especially the dry season flow (Adamsonn, 2006). This strong vulnerability of the Mekong hydrology towards climate change impacts requires profound research on the climate-hydrology interactions under different scenarios.

The ENSO phenomenon and its impact on climate variability in the Mekong region

The El Niño–Southern Oscillation (ENSO) is a well-known phenomenon. In South East Asia it is leading to low rainfall rates during el Niño years and higher precipitation in la Niña years (AchutaRao and Sperber, 2002; Räsänen & Kummu, 2012). Räsänen and Kummu (2012) analysed the correlation of the ENSO phenomenon with recent climate variations in the Mekong Basin for rainfall data (149 precipitation stations, 1981-2005) and discharge (six Mekong gauging stations, 1910-2008) using spatial GIS analyses and statistical methods, such as linear correlations, spectral analysis and stochastic regression models. They detected that the hydrological dynamics of the Mekong River were significantly influenced by ENSO events, especially the hydrological processes in the southern and central part of the basin. The precipitation and discharge data correlated particularly in the decay years of ENSO events decreasing during El Niño years with shorter annual flood periods and increasing during La Niña years with longer flood periods. Furthermore, they found out that the correlation between ENSO and the hydrological processes of the Mekong changed a lot in the period 1910-2008. From 1910 to 1940 and from 1975 to 2008 a strong correlation in the data could be observed, whereas between 1940 and 1975 low correlations were recorded (Räsänen & Kummu, 2013).
The irregular (every 2-7 years) El Niño and La Niña years originate in the tropical Pacific and are accompanied by interactions between the ocean and the atmosphere of the tropical Indian and Pacific Oceans. They have clear signals in sea surface temperature (SST), atmospheric pressure patterns and a varying strength of the Pacific trade winds. While El Niño years account for higher sea surface temperatures and lower air pressure in the Eastern Pacific, La Niña conditions are generated by cold sea surface temperatures originating in the tropical Pacific (Mc Phaden et al., 2006; Tudhope et al., 2001). Higher El Niño SSTs lead to higher evaporation rates and hence to above-average rainfall in the eastern Pacific and South America during winter and late spring. At the same time, it causes droughts in eastern Australia, South East Asia and storms along the equator. Measuring sea surface temperature and atmospheric pressure is considered as a suitable tool to predict El Niño and la Niña events and hence precipitation more than several months ahead (Montecinos & Aceituno, 2003). For the Mekong Basin, it is suggested to have a high potential for prediction of ENSO induced hydro-meteorological extremes, ENSO index values from December-February explained approximately 50% of the 562 inter-inter-annual variation of the Mekong’s following year discharge (Räsänen & Kummu, 2013).

 

References and further reading:

Adamson, P. T., Rutherfurd, I. D., Peel, M. C. Conlan, I. A. (2009) The Hydrology of the Mekong River,The Mekong: Biophysical Environment of an International River Basin, Academic Press Elsevier, 53-76.

ADB (2011) Lower Mekong Basin Component Flood Vulnerability Indices,TA-7276-REG Supporting Investments inWater-Related Disaster Management, Draft final report Asian Development Bank, 1-59.

Beechham, R., Cross, H. (2005) Modelled Impacts of Scoping Development Scenarios in the Lower Mekong Basin, Mekong River Commission, Cited by: MRC (2009d), Hydrological and Flood Hazards in the Lower Mekong Basin, Mekong River Commission Secretariat, Vientiane, Lao PDR, 1-324. 

Boucharel, J., Dewitte, D., du Penhoat P., Garel, B., Yeh, S.-W., Kug, J.-S. (2011) ENSO nonlinearity in a warming climate, Climate Dynamics 37: 2045–2065, DOI 10.1007/s00382-011-1119-9.

De Bruijn, K. M. (2005) Resilience and Flood Risk Management, A Systems Approach Applied to Lowland Rivers, Delft University Press, Delft, Netherlands.

Delgado, J. M., Merz, B., Apel, H. (2010) Flood trends and variability in the Mekong River, Hydrology and Earth System Sciences, 14, 407-418.

Doyle, T., Day, R., Michot, T. (2010) Development of sea level rise scenarios for climate change assessment of the Mekong Delta Vietnam, U.S. Geological Survey Open File Report 2010-1165, 110 p.

FIVAS (2007) Ruined Rivers, Damaged Lives, The Impact of the Theun-Hinboun Hydropower Project on Downstreams Communities in Lao PDR, FIVAS, Oslo, Norway, pp 66.

Flato, G. M., Boer, G. J., Lee, W. G., Mac Farlane, N. A., Ramsden, D., Reader, M. C., Weaver, A. J. (2000) The Canadian centre for climate modelling and analysis global coupled model and its climate, Clim Dyn 16: 451–467.

Fox, J., Vogler, J. B., Sen, O. L., Ziegler, A. L., Giambelluca, T. W. (2009)  Land cover and land use change Southeast Asia.

Fu, K. D., He, D. M., Lu, X.X. (2008)  Sedimentation in the Manwan reservoir in the Upper Mekong and its downstream impacts, Quaternary International, 186, 91-99.

Gao, G. Y., Fu, B. J., Lü, Y. H., Liu, Y., Wang, S., Zhou, J. (2012) Coupling the modified SCS-CN and RUSLE models to simulate hydrological effects of restoring vegetation in the Loess Plateau of China, Hydrology and Earth System Sciences, 16, 2347-2364.

GFDRR (Global Facility for Disaster Reduction and Recovery) (2011) Vulnerability, Risk Reduction, and Adaptation to Climate Change - Cambodia, World Bank, Washington, D.C.

Giorgi, F., Mearns, L. O. (2002) Probability of regional climate change based on the Reliability Ensemble Averaging (REA) method, Geophysical Research Letters, 30(12), June 2003.

Government of Lao PDR (2009) National Adaptation Programme of Action to Climate Change, Lao People’s Democratic Republic Peace Independence Democracy Unity Prosperity.

Gowing, J., Tuong, T., Hoanh, C. T., Khiem, N. (2006) Social and environmental impact of rapid change in the coastal zone of Vietnam: an assessment of sustainability issues, Environment and Livelihoods in Tropical Coastal Zones: Managing Agriculture–Fishery–Aquaculture Conflicts, CAB International, Wallingford, UK 48–60.

Grimsditch, M. (2012) 3S Rivers under Threat. Understanding new Threats and Challanges from Hydropower Development to Biodiversity and Community Rights in the 3S River Basin, 3S Protection Network and International Rivers, 1-78.

Grumbine, E., Dore, J., Xu, J. (2012) Mekong Hydropower: Drivers of Change and Governance Challenges, Front Ecol Environ, 10(2), 91-98.

Halls, A. S., Burnhill, T. J., Kshatriya, M. (2009) Modelling the Cumulative Barrier and Passage Effects of Mainstream Hydropower Dams on Migratory Fish Populations in the Lower Mekong Basin, MRC Technical Paper No 25, Vientiane, p. 103.

Hannaford, J., Lloyd-Hughes, B., Keef, S., Parryand, C., Prudhomme (2011) Examining the large-scale spatial coherence of European drought using regional indicators of precipitation and streamflow deficit, Journal for Hydrological Processes 25, 1146–1162, DOI: 10.1002/hyp.7725.

Hoanh, C. T., Guttman, H., Droogers, P., Aerts, J. (2003) ADAPT: Water, climate, food and environment under climate change, The Mekong basin in Southeast Asia, International Water Management Institute, Mekong River  Commission, Future Water, Institute of Environmental Studies. Colombo, Phnom-Penh, Wageningen.

Hoanh, C. T. et al. (2012) Modelling to support land and water management: experiences from the Mekong River  Delta, Vietnam, Water International, 37:4, 408-426.

IPCC (2012) Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation. A Special Report of Working Groups I and II of the Intergovernmental Panel on Climate Change [Field, C.B., V. Barros, T.F. Stocker, D. Qin, D.J. Dokken, K.L. Ebi, M.D. Mastrandrea, K.J. Mach, G.-K. Plattner, S.K. Allen, M. Tignor, and P.M. Midgley (eds.)], Cambridge University Press, Cambridge, UK, and New York, NY, USA, 582 pp.

Ishidaira, H., Ishikawa Y., Funada S., Takeuchi K. (2008) Estimating the evolution of vegetation cover and its hydrological impact in the Mekong River Basin in the 21st Century, Hydrol. Process, 22, 1395–1405.

Jiang, Y., Liu, J., Cui, Q., An, X., Wu, C. (2011) Land use/land cover change and driving force analysis in Xishuangbanna Region in 1986–2008, Frontiers of Earth Science.

Johns, T. C. et al. (2003) Anthropogenic climate change for 1860 to 2100 simulated with the HadCM3 model under updated emissions scenarios, Climate Dynamics, 20(6), 583-612.

Johnston, R., Lacombe, G., Hoanh, C. T., Noble, A., Pavelic, P., Smakhtin, V., Suhardiman, D., Pheng, K. S., Sze, C. P. (2010) Climate change, water and agriculture in the Greater Mekong Subregion, Colombo, Sri Lanka: International Water Management Institute, 60 p. (IWMI Research Report 136), doi:10.5337/2010.212.

Keskinen, M., Kummu, M. (2011) Impact Assessment in the Mekong–Review of Strategic Environmental Assessment (SEA) & Cumulative Impact Assessment (CIA), Espoo: Aalto University.

Keyantash, J. A., Dracup J. A. (2004) An aggregate drought index: Assessing drought severity based on fluctuations in the hydrologic cycle and surface water storage, Water Resources Research, 40(9).

Kite, G. (2001) Modeling the Mekong: hydrological simulation for environmental impact Studies, Journal of Hydrology 253, 1-3.

Mainuddin, M., Kirby, M., Hoanh, C.T. (2011) Adaptation to Climate Change for Food Security in the lower Mekong Basin, CSIRO (Commonwealth Scientific and Industrial Research Organisation), Canberra.

Mc Avaney, B. J. et al. (2001) Model Evaluation, J.T. Houghton, Y. Ding, D.J. Griggs, M. Noguer, P.J.v.d. Linden, X. Dai, K. Maskell and C.A. Johnson (Editors), Climate Change 2001: The Scientific Basis, Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change Cambridge University Press, Cambridge, UK, 471–524.

Mc Phaden, M. J.,  Zebiak, S. E., Glantz, M. H. (2006) ENSO as an Integrating Concept in Earth Science,  Science 15 December 2006: 314 (5806), 1740-1745. DOI:10.1126/science.1132588.

Montecino, A., Aceituno, P. (2003) Seasonality of the ENSO-Related Rainfall Variability in Central Chile and Associated Circulation Anomalies. American Meterological Society, 16, 281-296.

MMRC (2012) Working Paper 2011-2015, The Impact and Management of Flood and Droughts in the Lower Mekong Basin & the Implication of possible Climate Change, Flood Management and Mitigation Programme, p. 130.

Müller, D. (2004) From agricultural expansion to intensification: Rural development and determinants of land-use change in the Central Highlands of Vietnam, Tropical Ecology Support Programme (TOEB), Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ), F-VI/6e.

Randall, D. A. et al. (2007) Climate Models and their evaluation, in: S. Solomon, D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (Editors), Climate Change 2007: The Physical Basis, Cambridge University Press, Cambridge, UK, 590‐648.

Räsänen, T. A., Kummu, M. (2012) Spatiotemporal influences of ENSO on precipitation and flood pulse in the Mekong River Basin, Journal of Hydrology, doi: http://dx.doi.org/10.1016/j.jhydrol.2012.10.028.

Rerkasem, B. (2011) Climate Change and GMS Agriculture, in: Rayanakorn K (Eds.), Climate Change Challenges in the Mekong Region, Chiang Mai University Press, Chiang Mai.

Senevirathene, N., Mony, K., Samarakoon, L., Hazarika, M. K. (2011) Land use/land cover change detection of tonle sap watershed, Cambodia, AIT, Pathumathani, Thailand, 1-6.

Singh, A. S. (2007) Agriculture and Rural Development in the Greater Mekong Sub-Region, The Important Nexus, CUTS Hanoi Resource Centre, Hanoi.

Trisurat, Y., Alkemade, R., Verburg, P. H. (2010) Projecting Land-Use Change and Its Consequences for Biodiversity in Northern Thailand, Environmental Management 45(3), 626–639.

UNDP (2011) Mainstreaming Drought Risk Management - a primer, UNON Printshop, Nairobi United Nations Office at Nairobi (UNON), Publishing Services Section, ISO 14001:2004-certified/March 2011.

Vastila, K., Kummu, M., Sangmanee, C., Chinvanno, S. (2010) Modelling climate change impacts on the flood pulse in the Lower Mekong floodplains, Journal of Water and Climate Change 1(1): 67-86.

Wassmann, R., Hien, N. X., Hoanh, C. T., Tuong, T. P. (2004) Sea level rise affecting the Vietnamese Mekong Delta: water elevation in the flood season and implications for rice production, Institute for Meteorology and Climate Research (IMK-IFU), Forschungszentrum Karlsruhe, Kreuzeckbahnstr. 19, 82467.

Zhao, Q., Liu, S., Deng, L., Dong, S., Yang, Z., Liu, Q. (2012) Determining the influencing distance of dam construction and reservoir impoundment on land use: A case study of Manwan Dam, Lancang River. Ecological Engineering, Elsevier B.V., 1-8.