World Water Day – Water, Climate Change and Hydropower

Water, climate and energy are inextricably linked, writes IHA's Senior Analyst Cristina Diez Santos.


The theme of this year’s World Water Day, ‘Water and Climate Change’, connects two pillars of the International Hydropower Association’s strategy to advance sustainable hydropower. Water, climate and energy are inextricably linked. Yet too often decision-makers have taken the approach of managing policies and markets within separate silos. Integrated approaches are required to sustainably manage the use of these resources. This becomes even more significant as climate change starts to have an impact on the global hydrological system, increasing extreme weather events.

Hydropower is a major player on the world renewable energy stage, responsible for around 16 per cent of global electricity generation[i], and its infrastructure, if sustainably managed, provides vital freshwater services, such as water supply and storage, irrigation, flood control and drought prevention.

Current progress on the targets of Sustainable Development Goal (SDG) 6 on water and sanitation are alarmingly off-track. Data suggests that achieving universal access to basic sanitation service by 2030 would require doubling the current annual rate of progress.[ii] The International Hydropower Association therefore echoes the World Water Day’s theme and messages: We cannot afford to wait.

In the next 30 years, an increase in demand for water, energy and food of between 50 to 100 per cent is expected.[iii] Higher impacts on water availability and on ecosystems and socioeconomic systems connected with water are expected. Climate disruption will heighten the situation, increasing the importance of water storage and water conservation.


Besides the more efficient management of water to address the growing demand, it is estimated that the world needs over 1,000 GW of new hydropower capacity in the next 30 years to meet global climate change targets.[iv] That is a potential contribution of over 5 million km3 of additional stored water available for water supply, irrigation, drought mitigation and flood protection. [v] Hydropower, as a key player in the water-energy nexus, also has the responsibility to support the achievement of the 2030 Sustainable Development Agenda.

Nearly 70 per cent of global freshwater is stored with relatively long retention periods in ice caps, glaciers, permanent snow, and groundwater.[vi] With the rise in temperatures and melt of glaciers, reservoirs become more relevant as one of the main contributors to storage variability at seasonal and interannual scales. Moreover, existing reservoirs have the potential to help drop sea levels by about 0.55mm a year, [vii] helping to mitigate the sea level rise.

Hydropower systems, with their ability to store water behind dams in freshwater reservoirs, can provide several services (including irrigation, water supply, and flood control) that allow the water storage to be redistributed in space and time, providing a higher systemic resilience and capacity to adapt to climate change.

Globally, the International Commission on Large Dams (ICOLD) database reveals that 70 per cent of large dams are designed to be single purpose.[viii] According to a study by IHA, 60 per cent of the hydropower storage operational projects are single purpose.[ix] However, most of them evolve over time into multipurpose use. This evolution, if not managed, does not allow full realisation of the benefits and synergies of designing infrastructure to be multipurpose from inception.

Hydropower projects bring numerous economic and social benefits. However, the creation of reservoirs modifies existing natural ecosystems, interrupting the connectivity in the river basin. Dams trap and interrupt the cycle of sediments, nutrients, aquatic species and seeds. Thus, the design, construction and operation and maintenance of hydropower projects must be made in a sustainable way, considering all possible negative effects. Moreover, planning hydropower systems from a long-term, climate-resilient perspective will ensure that future generations inherit infrastructure that will not be compromised by climate change and will be able to provide a range of climate adaptation services.

IHA, in its mission to advance sustainable hydropower, has developed a set of tools relating to climate change mitigation and resilience, including the estimation and management of hydropower project’s greenhouse gas emissions (G-res Tool), and the analysis and management of the risks of climate change and climate change adaptation (Hydropower Sector Climate Resilience Guide).


We are a champion of good practices and continuous improvement in the hydropower sector, supporting project assessments and training with the Hydropower Sustainability Tools, and sharing industry experiences on sediment management through a Knowledge Hub and How-To Guide.

Today, more than ever, the global community is focusing on the need for low-carbon, reliable and resilient power systems. We have the opportunity to address policy, capacity building, and market and financing constraints to further promote hydropower to help achieve sustainable targets on energy (SDG7), water (SDG6), and climate (SDG13).

IHA will continue working to raise awareness and share good practices about the freshwater management services that hydropower provides to advance the achievement of the Sustainable Development Goals. For more information please follow us on Twitter, Facebook and LinkedIn. Download and share social media cards.

Cristina Diez Santos


[i] IEA World Energy Outlook 2019

[ii] https://sustainabledevelopment.un.org/sdg6

[iii] https://sustainabledevelopment.un.org/sdg6

[iv] IRENA, Global energy transformation: A roadmap to 2050 (2019 edition)

[v] IHA and ICOLD databases

[vi] USGS, 2014: One estimate of global water distribution. The World’s Water, U.S. Geological Survey, accessed 4 June 2014. [Available online at http://water.usgs.gov/edu/earthwherewater. html.]

[vii] Lettenmaier, D. P., and J. S. Famiglietti, 2006: Hydrology: Water from on high. Nature, 444, 562–563, doi:10.1038/444562a. ——, and P. Milly, 2009: Land waters and sea level. Nat. Geosci., 2, 452–454, doi:10.1038/ngeo567.

[viii] ICOLD database

[ix] Hydropower Status Report 2019

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