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Ion, I.V.; Ene, A. Greenhouse Gas Emissions from Reservoirs. Encyclopedia. Available online: (accessed on 20 April 2024).
Ion IV, Ene A. Greenhouse Gas Emissions from Reservoirs. Encyclopedia. Available at: Accessed April 20, 2024.
Ion, Ion V., Antoaneta Ene. "Greenhouse Gas Emissions from Reservoirs" Encyclopedia, (accessed April 20, 2024).
Ion, I.V., & Ene, A. (2021, November 02). Greenhouse Gas Emissions from Reservoirs. In Encyclopedia.
Ion, Ion V. and Antoaneta Ene. "Greenhouse Gas Emissions from Reservoirs." Encyclopedia. Web. 02 November, 2021.
Greenhouse Gas Emissions from Reservoirs

Reservoirs are manmade lakes created by building dams on rivers for various purposes: flood control, electricity generation, irrigation, water supply, aquaculture, environmental services, recreational activities, navigation etc. In freshwater ecosystems, several mechanisms are involved in the natural carbon cycle. They receive carbon from terrestrial ecosystems through drainage, capture the carbon through primary production, bury the carbon in sediments, emit GHG through biomass degradation and respiration, and transport the carbon downstream to the seas or oceans. GHG emissions can be increased by human activities around the ecosystem through sewage and agricultural pollution.

greenhouse gas multipurpose reservoirs sustainability

1. Introduction

Dams affect the natural carbon cycle in freshwater ecosystems through floods of terrestrial vegetation and soils. The flooded organic matter decomposes causing additional GHG emissions, especially in the first years after the reservoir creation. Flooding can also increase sedimentation and decomposition in the reservoir, due to longer water residence times, which can lead to higher GHG emissions [1]. In addition, reservoirs can have large fluctuations in the water level, especially hydroelectric reservoirs that store large volumes of water to be used during drought. It can, therefore, be said that artificial reservoirs differ from natural lakes by riverine nutrient inputs, the flooding of terrestrial organic carbon, and water-level fluctuations; they also may have different GHG emissions. Reservoirs present, from a social, economic and environmental point of view, not only advantages, but also disadvantages.

2. The Use of Reservoir

Reservoir use can serve single or multiple purposes. According to the International Commission on Large Dams (ICOLD), 70% of large reservoirs are designed for single-purpose usage. Around 11% of large reservoirs have been built only for hydropower generation and 14% for hydropower generation plus other uses. These high figures show why GHG emissions from reservoirs should be accounted for. In addition, the study of these emissions indicates ways to reduce them.

3. Greenhouse Gases

The main greenhouse gases emitted by a reservoir are CO2, CH4 and N2O. They have a different global warming potential (GWP). For the time period of 100 years, GWP for CO2 is 1; for CH4, it is 34 times higher than that of CO2, and for N2O, it is 298 times that of CO2 [2].
The CO2 is generated by the decomposition of organic material and nutrients transported in the reservoir by affluent or by rainfall and overland flow, by the decomposition of dead organic matter stored in the soil of the reservoir, by the respiration of vegetation present in the reservoir, from CO2 dissolved in water and from the oxidation of CH4. The sediments in drawdown areas are also a source of CO2 emission, due to their exposure to air during water level fluctuations.
The emission of CH4 comes from the decomposition of organic matter and vegetation under anaerobic conditions in the soil or sediment layer of the reservoir.
Nitrous oxide (N2O) arises as a by-product of the aerobic nitrification reaction or of the anaerobic denitrification that occurs in lake riparian areas. The few measurements of N2O emission from reservoirs showed a variation similar to that of CH4 in terms of generation. The contribution of N2O to the total GHG emission expressed as an CO2 equivalent is low, compared to CH4 și CO2 (N2O—17 mg CO2eq/m2/d; CH4—275 mg CO2eq/m2/d and CO2—1585 mg CO2/m2/d) [3].
GHG (CO2 and CH4) reaches the atmosphere through the following channels: diffusive flow from the reservoir surface, through degassing when passing through the hydraulic turbine and spillway (due to pressure drop), through diffusive flow at the downstream river surface. Methane can also reach the surface of the reservoir through bubbling in shallow areas of reservoir.
The main factors influencing GHG emissions are the carbon stock in soil and flooded biomass or that transported by the upstream rivers in reservoirs; the concentration of dissolved oxygen in the reservoir; water quality and nutrient content; the inflow and shape of the reservoir; the water depth and extension of the littoral zone; the wind speed at the reservoir surface; and the water temperature and configuration of dam intake and outlets [3]. These factors influence the biochemical processes of organic matter formation, respiration, methanogenesis, CH4 oxidation, gas exchange between the reservoir and the atmosphere. The GHG measurements showed a variation in time and space within a reservoir and also a seasonal variation and a decrease in general with the age of the reservoir.
There are many studies on the evaluation of GHG emissions from reservoirs, which differ by the methodologies used, the lifespan considered, and the size and type of reservoir [1][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39].
Most studies have analyzed GHG emissions from hydropower reservoirs. The few studies performed on natural lakes have shown that there are no significant differences between reservoir surface emissions from hydropower reservoirs, compared to non-hydropower reservoirs [10]. At hydropower reservoirs, there are also degassing emissions, downstream emissions and emissions from drawdown zones.
From the analysis of GHG emissions from 85 different hydroelectric reservoirs with a global distribution, it was observed that all the reservoirs are sources of CH4 to the atmosphere, the majority (88%) are also a source of CO2 (only 12% of reservoirs are net sinks of CO2) and that there is a large variation in emissions [5].
Knowing the GHG emissions generated by reservoirs is an important factor in making decisions to finance future projects and discerning how environmentally friendly they are.

4. Conclusions

Built to meet human needs, multipurpose reservoirs increase human well-being, but they cause changes in the water quality, ecosystem and flow regime of river networks. They are considered neutral in terms of GHG emissions, but they may become considerable sources of GHG depending, especially, on the climatic zone in which they are located and their uses. The creation of a water reservoir on a river leads to the generation of GHG, due to biogeochemical processes in the reservoir. The calculation of GHG emissions of the studied reservoir, which is placed in a temperate zone and has multiple uses of water, shows that they are lower than those of a lake (306.85 g CO2eq/m2/yr versus 953.73 g CO2eq/m2/yr).
Knowing the GHG emissions from the reservoir is useful to accurately report the greenhouse gas (GHG) emissions. To calculate the CO2 emission, four models were used; to calculate the CH4 emission, six models were used. If the difference between the highest (520 mg CO2/m2/d) and the lowest CO2 emission value (205.48 mg CO2/m2/d) is more than two-fold, the difference between the highest CH4 emission (76.52 mg CH4/m2/d) and the lowest emission value (1.16 CH4 mg CH4/m2/d) is much larger, by about 65 times.
Because not all the methodologies reviewed make an overall assessment of GHG emissions and because some are used only for hydropower reservoirs—except the G-res tool, which estimates the GHG emissions from the reservoir surface, drawdown, turbines and spillway—it is difficult to compare the results obtained by applying the methodologies to the multipurpose reservoir, Stânca-Costești.
In the absence of a standardized methodology for calculating GHG emissions from the reservoirs, the reviewed models can be used in correlation with the available data on reservoirs.


  1. Levasseur, A.; Mercier-Blais, S.; Prairie, Y.T.; Tremblay, A.; Turpin, C. Improving the accuracy of electricity carbon footprint: Estimation of hydroelectric reservoir greenhouse gas emissions. Renew. Sust. Energ. Rev. 2021, 136, 110433.
  2. IPCC (Intergovernmental Panel on Climate Change). 2006 IPCC Guidelines for National Greenhouse Gas Inventories; Eggleston, H.S., Buendia, L., Miwa, K., Ngara, T., Tanabe, K., Eds.; Institute for Global Environmental Strategies (IGES): Kanagawa, Japan, 2006.
  3. World Bank. Greenhouse Gases from Reservoirs Caused by Biogeochemical Processes; World Bank: Washington, DC, USA, 2017; Available online: (accessed on 16 December 2020).
  4. Almeida, R.M.; Paranaíba, J.R.; Barbosa, Í.; Sobek, S.; Kosten, S.; Linkhorst, A.; Mendonça, R.; Quadra, G.; Roland, F.; Barros, N. Carbon dioxide emission from drawdown areas of a Brazilian reservoir is linked to surrounding land cover. Aquat. Sci. 2019, 81, 68.
  5. Barros, N.; Cole, J.J.; Tranvik, L.J.; Prairie, Y.T.; Bastviken, D.; Huszar, V.L.M.; del Giorgio, P.; Roland, F. Carbon emission from hydroelectric reservoirs linked to reservoir age and latitude. Nat. Geosci. 2011, 4, 593–596.
  6. Bastviken, D.; Cole, J.; Pace, M.; Tranvik, L. Methane emissions from lakes: Dependence of lake characteristics, two regional assessments, and a global estimate. Glob. Biogeochem. Cycles 2004, 18, GB4009.
  7. Bastviken, D.; Tranvik, L.J.; Downing, J.A.; Crill, P.M.; Enrich-Prast, A. Freshwater methane emissions offset the continental carbon sink. Science 2011, 331, 50.
  8. Chen, H.; Wu, Y.Y.; Yuan, X.Z.; Gao, Y.S.; Wu, N.; Zhu, D. Methane emissions from newly created marshes in the drawdown area of the Three Gorges Reservoir. J. Geophys. Res. 2009, 114, D18301.
  9. Chen, Z.; Ye, X.; Huang, P. Estimating Carbon Dioxide (CO2) Emissions from Reservoirs Using Artificial Neural Networks. Water 2018, 10, 26.
  10. Deemer, B.R.; Harrison, J.A.; Li, S.; Beaulieu, J.J.; Delsontro, T.; Barros, N.; Bezerra-Neto, J.F.; Powers, S.M.; Dos Santos, M.A.; Vonk, J.A. Greenhouse gas emissions from reservoir water surfaces: A new global synthesis. Bioscience 2016, 66, 949–964.
  11. Du, H.L.; Li, Z.; Guo, J.S. Carbon footprint of a large hydropower project in the upstream of the Yangtze: Following ISO14067. Resour. Environ. Yangtze Basin 2017, 26, 1102–1110.
  12. Gallagher, J.; Styles, D.; McNabola, A.; Williams, A.P. Life cycle environmental balance and greenhouse gas mitigation potential of micro-hydropower energy recovery in the water industry. J. Clean Prod. 2015, 99, 152–159.
  13. Galy-Lacaux, C.; Delmas, R.; Kouadio, J.; Richard, S.; Gosse, P. 1999, Long-term Greenhouse Gas Emissions from Hydroelectric Reservoirs in Tropical Forest Regions. Glob. Biogeochem. Cycles 1999, 13, 503–517.
  14. Jiang, T.; Shen, Z.; Liu, Y.; Hou, Y. Carbon Footprint Assessment of Four Normal Size Hydropower Stations in China. Sustainability 2018, 10, 2018.
  15. Kadiyala, A.; Kommalapati, R.; Huque, Z. Evaluation of the Life Cycle Greenhouse Gas Emissions from Hydroelectricity Generation Systems. Sustainability 2016, 8, 539.
  16. Li, S.; Zhang, Q. Carbon emission from global hydroelectric reservoirs revisited. Environ. Sci. Pollut. Res. 2014, 21, 13636–13641.
  17. Li, X.; Gui, F.; Li, Q. Can Hydropower Still Be Considered a Clean Energy Source? Compelling Evidence from a Middle-Sized Hydropower Station in China. Sustainability 2019, 11, 4261.
  18. Mäkinen, K.; Khan, S. Policy considerations for greenhouse gas emissions from freshwater reservoirs. Water Altern. 2010, 3, 91–105.
  19. Mosher, J.J.; Fortner, A.M.; Phillips, J.R.; Bevelhimer, M.S.; Stewart, A.J.; Troia, M.J. Spatial and Temporal Correlates of Greenhouse Gas Diffusion from a Hydropower Reservoir in the Southern United States. Water 2015, 7, 5910–5927.
  20. Prakash, R.; Bhat, I.K. Life cycle greenhouse gas emissions estimation for small hydropower schemes in India. Energy 2012, 44, 498–508.
  21. Prairie, Y.T.; Alm, J.; Beaulieu, J.; Barros, N.; Battin, T.; Cole, J.; del Giorgio, P.; Del Sontro, T.; Guérin, F.; Harby, A.; et al. Greenhouse gas emissions from freshwater reservoirs: What does the atmosphere see? Ecosystems 2017, 21, 1058–1071.
  22. Prairie, Y.T.; Alm, J.; Harby, A.; Mercier-Blais, S.; Nahas, R. The GHG Reservoir Tool (Gres) Technical documentation v2.1 (2019-08-21). UNESCO/IHA research project on the GHG status of freshwater reservoirs; Joint publication of the UNESCO Chair in Global Environmental Change and the International Hydropower Association: London, UK, 2017; Available online: (accessed on 30 March 2021).
  23. Prairie, Y.T.; Mercier-Blais, S.; Harrison, J.A.; Soued, C.; Del Giorgio, P.; Harby, A.; Alm, J.; Chanudet, V.; Nahas, R. A new modelling framework to assess biogenic GHG emissions from reservoirs: The G-res, tool. Environ. Model Softw. 2021, 143, 105117.
  24. Rosa, L.P.; dos Santos, M.A.; Matvienko, B.; Sikar, E. Hydroelectric reservoirs and global warming. In Proceedings of the RIO 02—World Climate and Energy Event, Rio de Janeiro, Brazil, 6–11 January 2002; pp. 123–129. Available online: (accessed on 10 April 2021).
  25. Rosa, L.P.; dos Santos, M.A.; Matvienko, B.; dos Santos, E.O.; Sikar, E. Greenhouse Gases Emissions by Hydroelectric Reservoirs in Tropical Regions. Clim. Chang. 2004, 66, 9–21.
  26. Scherer, L.; Pfister, S. Hydropower’s Biogenic Carbon Footprint. PLoS ONE 2016, 11, e0161947.
  27. Song, C.; Gardner, K.H.; Klein, S.J.W.; Souza, S.P.; Mo, W. Cradle-to-grave greenhouse gas emissions from dams in the United States of America. Renew. Sustain. Energ. Rev. 2018, 90, 945–956.
  28. St. Louis, V.L.; Kelly, C.A.; Duchemin, É.; Rudd, J.W.M.; Rosenberg, D.M. Reservoir surfaces as sources of greenhouse gases to the atmosphere: A global estimate. BioScience 2000, 50, 766–775.
  29. Suwanit, W.; Gheewala, S.H. Life cycle assessment of mini-hydropower plants in Thailand. Int. J. LCA 2011, 16, 849–858.
  30. Zhang, Q.F.; Karney, B.; MacLean, H.L.; Feng, J.C. Life-cycle inventory of energy use and greenhouse gas emissions for two hydropower projects in China. J. Infrastruct. Syst. 2007, 13, 271–279.
  31. Zhang, S.R.; Pang, B.H.; Zhang, Z.L. Carbon footprint analysis of two different types of hydropower schemes: Comparing earth-rockfill dams and concrete gravity dams using hybrid life cycle assessment. J. Clean Prod. 2015, 103, 854–862.
  32. Schlömer, S.; Bruckner, T.; Fulton, L.; Hertwich, E.; McKinnon, A.; Perczyk, D.; Roy, J.; Schaeffer, R.; Sims, R.; Smith, P.; et al. Annex III: Technology-specific cost and performance parameters. In Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change; Edenhofer, O., Pichs-Madruga, R., Sokona, Y., Minx, J.C., Farahani, E., Kadner, S., Seyboth, K., Adler, A., Baum, I., Brunner, S., et al., Eds.; Cambridge University Press: New York, NY, USA, 2014.
  33. Myhre, G.; Shindell, D.; Bréon, F.M.; Collins, W.; Fuglestvedt, J.; Huang, J.; Koch, D.; Lamarque, J.F.; Lee, D.; Mendoza, B.; et al. Anthropogenic and Natural Radiative Forcing. In Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change; Stocker, T.F., Qin, D., Plattner, G.-K., Tignor, M., Allen, S.K., Boschung, J., Nauels, A., Xia, Y., Bex, V., Midgley, P.M., Eds.; Cambridge University Press: Cambridge, UK; New York, NY, USA, 2013.
  34. Li, Z.; Du, H.L.; Xiao, Y.; Guo, J.S. Carbon footprints of two large hydro-projects in China: Life-cycle assessment according to ISO/TS 14067. Renew. Energy 2017, 114, 534–546.
  35. IEA Hydropower. Annex XII: Guidelines for Quantitative Analysis of Net GHG Emissions from Reservoirs. 2012. Available online: (accessed on 23 November 2020).
  36. Lovelock, C.E.; Evans, C.; Barros, N.; Prairie, Y.; Alm, J.; Bastviken, D.; Beaulieu, J.J.; Garneau, M.; Harby, A.; Harrison, J.; et al. 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Volume 4: Agriculture, Forestry and Other Land Use (Chapter 7: Wetlands); IPCC: Kanagawa, Japan, 2019.
  37. Goldenfum, J.A. (Ed.) UNESCO/IHA GHG Measurement Guidelines for Freshwater Reservoirs; International Hydropower Association (IHA): London, UK, 2010.
  38. Vilela, T.; Reid, J. Improving hydropower choices via an online and open access tool. PLoS ONE 2017, 12, e0179393.
  39. Bergier, I.; Bambace, L.; Ramos, F.M. GHG life cycle analysis and novel opportunities arising from emerging technologies developed for tropical dams. In Proceedings of the UNESCO-IHP Workshop on the Greenhouse Gas Status of Freshwater Reservoirs, Foz do Iguaçu, Brazil, 4–5 October 2007; Available online: (accessed on 15 April 2021).
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Update Date: 03 Nov 2021