River flow

Assessment versions

Published (reviewed and quality assured)

• River flow (CLIM 016) - Assessment published Nov 2012

Justification for indicator selection

River flow is a measure of overall fresh water availability in a river basin. Variations in river flow are determined mainly by the seasonality of precipitation and temperature, as well as by catchment characteristics such as geology, soils and land cover. Changes in temperature and precipitation patterns due to climate change modify the annual water budget of river basins as well as the timing and seasonality of river flows. The consequent changes in water availability may adversely affect ecosystems and several socio-economic sectors including abstraction for drinking water, agriculture, industry, energy production and navigation. Extreme dry periods with low river flow events can have considerable economic, societal and environmental impacts.

Scientific references:

• . Alcamo, Joseph, Martina Flörke, and Michael Märker. 2007. “Future Long-term Changes in Global Water Resources Driven by Socio-economic and Climatic Changes.” Hydrological Sciences Journal 52 (2) (April): 247–275. doi:10.1623/hysj.52.2.247. BAFU. 2012. Auswirkungen der Klimaänderung auf Wasserressourcen und Gewässer: Synthesebericht zum Projekt «Klimaänderung und Hydrologie in der Schweiz» (CCHydro). Bern: Bundesamt für Umwelt. Beniston, Martin, Markus Stoffel, and Margot Hill. 2011. “Impacts of climatic change on water and natural hazardsin the Alps: Can current water governance cope with future challenges? Examples from the European ‘“ACQWA”’ project.” Environmental Science and Policy 14 (7): 734–743. doi:10.1016/j.envsci.2010.12.009. Birsan, Marius-Victor, Peter Molnar, Paolo Burlando, and Martin Pfaundler. 2005. “Streamflow trends in Switzerland.” Journal of Hydrology 314 (1-4) (November): 312–329. doi:10.1016/j.jhydrol.2005.06.008. Dankers, Rutger, and Luc Feyen. 2009. “Flood hazard in Europe in an ensemble of regional climate scenarios.” Journal of Geophysical Research 114 (D16) (August 27). doi:10.1029/2008JD011523. http://www.agu.org/pubs/crossref/2009/2008JD011523.shtml. Milly, P. C. D., K. A. Dunne, and A. V. Vecchia. 2005. “Global Pattern of Trends in Streamflow and Water Availability in a Changing Climate.” Nature 438 (7066) (November 17): 347–350. doi:10.1038/nature04312. Rojas, R., L. Feyen, A. Bianchi, and A. Dosio. 2012. “Assessment of Future Flood Hazard in Europe Using a Large Ensemble of Bias Corrected Regional Climate Simulations.” Journal of Geophysical Research (in press). doi:10.1029/2012JD017461. Stahl, K., H. Hisdal, J. Hannaford, L. M. Tallaksen, H. A. J. van Lanen, E. Sauquet, S. Demuth, M. Fendekova, and J. Jódar. 2010. “Streamflow trends in Europe: evidence from a dataset of near-natural catchments.” Hydrology and Earth System Sciences 14 (12) (December 1): 2367–2382. doi:10.5194/hess-14-2367-2010. Stahl, K., H. Hisdal, L. Tallaksen, H. A.J. Lanen, J. Hannaford, and E. Sauquet. 2008. Trends in Low Flows and Streamflow Droughts Across Europe. Paris: UNESCO. http://library.wur.nl/WebQuery/wurpubs/374150. Wilson, Donna, Hege Hisdal, and Deborah Lawrence. 2010. “Has Streamflow Changed in the Nordic Countries? – Recent Trends and Comparisons to Hydrological Projections.” Journal of Hydrology 394 (3–4) (November 26): 334–346. doi:10.1016/j.jhydrol.2010.09.010.

Indicator definition

• Trends in monthly stream flow

• Projected change in average annual and seasonal river flow

• Projected change in daily average river flow

Units

• standard deviations per year
• %
• m³/s

Policy context and targets

Context description

In April 2009 the European Commission presented a White Paper on the framework for adaptation policies and measures to reduce the European Union's vulnerability to the impacts of climate change. The White Paper stresses the need to improve the knowledge base and to mainstream adaptation into existing and new EU policies. The European Commission will be publishing an EU Adaptation Strategy in 2013. A number of Member States have already taken action, and several have prepared national adaptation plans.

The European Commission and the European Environment Agency have developed the European Climate Adaptation Platform (Climate-ADAPT, http://climate-adapt.eea.europa.eu/) to share knowledge on observed and projected climate change and its impacts on environmental and social systems and on human health; on relevant research; on EU, national and subnational adaptation strategies and plans; and on adaptation case studies.

Targets

No targets have been specified.

Related policy documents

• Climate-ADAPT: Mainstreaming adaptation in EU sector policies
  Overview of EU sector policies in which mainstreaming of adaptation to climate change is ongoing or explored
• Climate-ADAPT: National adaptation strategies
  Overview of activities of EEA member countries in preparing, developing and implementing adaptation strategies
• DG Climate Action: What is the EU doing about climate change?
  Activities of the EU regarding climate change (both mitigation and adaptation)
• White paper - Adapting to climate change: towards a European framework for action
  EU framework for adaptation to climate change, leading to a comprehensive EU adaptation strategy by 2013

Methodology

Methodology for indicator calculation

Streamflow trends are calculated by the slopes of the Kendall-Theil robust line for standardized annual and monthly streamflow, as well as for summer low flow magnitude and timing. Streamflow records from 441 small catchments in 15 countries across Europe.

Projected change in mean annual and seasonal river flow between the climate change scenario (SRES A1B, 2071–2100) and the control period (1961–1990) are shown. Simulations with LISFLOOD based on an ensemble of 11 RCMs.

Projected change in daily average river flow between 1961–1990 (black line) and 2071–2100 (blue line) were simulated with LISFLOOD and driven by HIRHAM – HadAM3H/HadCM3 based on IPCC scenario A2.

Methodology for gap filling

Not applicable

Methodology references

• Stahl et al. (2010) Streamflow trends in Europe: evidence from a dataset of near-natural catchments. Stahl, K., Hisdal, H., Hannaford, J., Tallaksen, L. M., van Lanen, H. A. J., Sauquet, E., Demuth, S., Fendekova, M. and Jódar, J., Hydrology and Earth System Sciences 14(12), 2367–2382. doi:10.5194/hess-14-2367-2010
• Rojas et al. (2012) Assessment of Future Flood Hazard in Europe Using a Large Ensemble of Bias Corrected Regional Climate Simulations. Rojas, R., Feyen, L., Bianchi, A. and Dosio, A. Journal of Geophysical Research (in press). doi:10.1029/2012JD017461

Data specifications

EEA data references

• No datasets have been specified here.

External data references

• Global trends in streamflow and water availability
• Global Runoff Database

Data sources in latest figures

Uncertainties

Methodology uncertainty

Not applicable

Data sets uncertainty

Detailed data on water quantity is often difficult to assess, and homogeneous time series are generally shorter than those for meteorological data. It may, therefore, require substantially more time before statistically significant changes in hydrological variables can be observed than for meteorological variables, especially with respect to extreme events (floods and droughts). Quantitative projections of changes in precipitation and river flows at the basin scale remain highly uncertain due to the limitations of climate models and to scaling issues between climate and hydrological models.

Further information on uncertainties is provided in Section 1.7 of the EEA report on Climate change, impacts, and vulnerability in Europe 2012 (http://www.eea.europa.eu/publications/climate-impacts-and-vulnerability-2012/)

Rationale uncertainty

No uncertainty has been specified