ICOLD gets technical about climate change

26 March 2019



Emmanuel Grenier is the Public Relations Officer for the International Commission on Large Dams. Here he gives an insight into the work being carried out by its technical committee on climate change.


The ICOLD Technical Committee on Global Climate Change and Dams, Reservoirs and the Associated Water Resources was first established in 2008. Climate change was of course a subject already discussed inside ICOLD but until now, we were relying mainly on the work of the Intergovernmental Panel on Climate Change (IPCC) and we were arguing in favour of hydropower because of the weak emissions of greenhouse gases of this power-producing technology. The commission decided that, with the climate change becoming real, there was a need for studying the way dam operators could adapt to its consequences.

The goal was of course not to repeat the content of the IPCC Reports, but to work on what it meant for dam operators and to make concrete recommendations for professionals.

Getting technical

The Technical Committee on Climate Change group together 17 members named by the national committees of different countries, plus 21 co-opted members or corresponding members, chosen for their specific competences and skills. Those experts come from the main dam building nations: USA, China, Iran, Spain, France, Canada, Japan, Norway, Spain, South Korea, etc. That is a typical composition of a Technical Committee of ICOLD.

The mandate received from ICOLD General Assembly was to:

  • Collect and review the guidance and policies currently used in planning for the impacts of global climate change on dams, reservoir, and the associated water resources.
  • Assess the role of dams and reservoirs in adapting to the effects of global climate change, and determine the threat posed by global climate change to existing dams and reservoirs.
  • Recommend measures designed to mitigate against or adapt to the effects of global change on water storage facilities. Such recommendations would be developed in light of scientific predictions of future climate changes; possible impacts from factors such as: increased or decreased precipitation, a change in the rate of evapo-transpiration, water quality, erosion, and siltation, prolonged drought, flooding.
  • Publish an ICOLD position paper and guidelines for climate change and dams, reservoirs and the associated water resources. These documents would be used by the ICOLD membership, governments, the United Nations, the World Bank and other organizations in need of guidance with respect to water resource protection and development.

After beginning its work, the technical committee has decided to add an objective to the bulletin: Provide up-to-date information about the potential of greenhouse gas emissions associated to reservoirs and related water systems existence and operation.

There has been one publication already, which is available on ICOLD's website in a preprint format. (https://www.icold-cigb.org/GB/publications/bulletins.asp) called Global Climate Change, Dams, Reservoirs, and Related Water Resources. There is also the publication of the Rabat Recommendations. Before the COP 22 meeting in Marrakech, the Moroccan government organised in Rabat, in July 1996, a pre-conference event was s dedicated to water. A workshop was co-organized by ICOLD, the Moroccan Committee on Large Dams and the Technical Committee on Climate Change, on the subjects dams and climate change.

Remain active

The committee will remain active to address climate change related problems and to disseminate knowledge and good practice examples of adaptation of reservoir management to climate change consequences. It has decided to structure its work in following three complementary themes:

  • Theme 1: Climate-induced Water shortage and Drought Management
  • Theme 2: Flood risk evolution associated to climate change
  • Theme 3: Assess the role of hydropower in climate change mitigation and new energy mix

So far, it has not yet been decided which Theme will be dealt first. The basis of the work is to start with case studies that could clearly illustrate each theme and derive generic guidelines based on these actual examples.

An important part of our work is presenting regional case studies of adaptation to climate impact. We have case studies that cover different climatic situations around the world ranging from the arid regions of south-east Australia and west Texas in the USA, to the temperate climate of Japan, tropical Guyana and the alpine region of France. In various parts of the world the impacts of climate change are significantly different and the problems encountered are of course also different.

The Committee is working on all the topics that seem appropriate in the framework of its mandate. For example, although it was not mentioned initially in the Terms of Reference voted by the General Assembly of ICOLD, the committee thought it was necessary to discuss the GHG emissions from dams and reservoirs, because it is something often raised by dam opponents and it is a subject which need clarifications and rational discussions.

On this chapter, we have discussed the possibilities of reducing GHG emissions from reservoirs and here are our three main conclusions:

  • We need to favour smaller reservoir surface/water volume ratio and consequently short residence time and less organic matter flooded;
  • When measuring GHG emissions, all pathways should be taken into account (diffusion, ebullition, degassing) and a particular attention should be towards measuring methane and determining net GHG
  • GHG emissions should be considered right from the conception phase. If the water intake to the power turbines is located near the surface of the reservoir or through flexible gates drawing water mostly from the surface of the reservoir, the risk of downstream degassing of methane is much lower. If water to the turbines is fed from the oxygen-depleted water closer to the bottom of the reservoir (hypolimnion), dissolved methane may be carried with the water and degassed downstream of the power plant. The use of bottom gates for releasing water or flushing the reservoir may also increase the risk of downstream methane emissions for the same reason. Hydro operations ensuring that water stays inside the reservoir for short periods of time will reduce the risk for emitting GHG. 

Meeting ICOLD Committee on Climate Change meeting in Prague, during ICOLD’s 85th Annual Meeting, July 2017. In the foreground is Committee Chairman Denis Aelbrecht (France).
Members The members of the Committee, during their meeting in July 2017 in Prague.


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