River floods

Assessment versions

Published (reviewed and quality assured)

• No published assessments

Rationale

Justification for indicator selection

There are many different types of floods. They can be distinguished based on the source of the flooding (e.g. rivers and lakes, urban storm water and combined sewage overflow, or seawater), the mechanism of flooding (e.g. natural exceedance, defence or infrastructure failure, or blockage) or other characteristics (e.g. flash flooding, snowmelt flooding or flooding caused by debris flows). This terms used in this indicator are explained below:

• River floods occur when water levels exceed the channel capacity and spill into adjacent areas. This is the most common type of flood.
• Pluvial floods occur when the absorption capacity of the soil or — in urban areas — the drainage capacity of the drainage system is exceeded.
• Flash floods refer to floods that occur within 3-6 hours of a heavy rainfall. Both river and pluvial floods can also be flash floods.

River floods are a common natural disaster in Europe and — along with storms — are the most important natural hazard in Europe in terms of economic damage. River floods can result in huge economic losses as a result of damage to infrastructure, property and agricultural land, and indirect losses in or beyond the flooded areas, such as production losses caused by damaged transport or energy infrastructures. They can also lead to loss of life, especially in the case of flash floods, and displacement of people, and can have adverse effects on human health, the environment and cultural heritage.

Scientific references

• IPCC, 2014: Europe. Kovats, R.S., R. Valentini, L.M. Bouwer, E. Georgopoulou, D. Jacob, E. Martin, M. Rounsevell, and J.-F. Soussana, 2014: Europe. In: Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part B: Regional Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Barros, V.R., C.B. Field, D.J. Dokken, M.D. Mastrandrea, K.J. Mach, T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S. MacCracken, P.R. Mastrandrea, and L.L. White (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1267-1326.

Indicator definition

This indicator monitors:

• observed regional trends in river flood discharges;

• projected changes in river floods with a return period of 100 years.

Units

• % change per decade

• Percentage change (%)

Policy context and targets

Context description

In April 2013, the European Commission presented the EU adaptation strategy package. This package consists of the EU strategy on adaptation to climate change (COM/2013/216 final) and a number of supporting documents. The overall aim of the EU adaptation strategy is to contribute to a more climate-resilient Europe. One of the objectives of the EU adaptation strategy is to allow 'Better informed decision-making'. This will be achieved by bridging knowledge gaps and further developing the European climate adaptation platform (Climate-ADAPT) as the ‘first-stop shop’ for adaptation information in Europe. Climate-ADAPT has been developed jointly by the European Commission and the European Environment Agency (EEA) to share knowledge on (1) observed and projected climate change and its impacts on environmental and social systems and on human health, (2) relevant research, (3) EU, transnational, national and subnational adaptation strategies and plans, and (4) adaptation case studies. It was relaunched in early 2019 with a new design and updated content. Further objectives include 'Promoting adaptation in key vulnerable sectors through climate-proofing EU sector policies' and 'Promoting action by Member States'.

In November 2018, the Commission published its evaluation of the 2013 EU adaptation strategy. The evaluation package includes a report from the Commission, a Commission staff working document, adaptation preparedness scoreboard country fiches and reports from the JRC Peseta III project. This evaluation includes recommendations for the further development and implementation of adaptation policies at all levels.

In November 2013, the European Parliament and the Council of the European Union adopted the EU's Seventh Environment Action Programme (7th EAP) to 2020, ‘Living well, within the limits of our planet’. The 7th EAP is intended to help guide EU action on environment and climate change up to and beyond 2020. It highlights that ‘Action to mitigate and adapt to climate change will increase the resilience of the Union’s economy and society, while stimulating innovation and protecting the Union’s natural resources.’ Consequently, several priority objectives of the 7th EAP refer to climate change adaptation.

Targets

No targets have been specified.

Related policy documents

• 7th Environment Action Programme
  DECISION No 1386/2013/EU OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 20 November 2013 on a General Union Environment Action Programme to 2020 ‘Living well, within the limits of our planet’. In November 2013, the European Parliament and the European Council adopted the 7 th EU Environment Action Programme to 2020 ‘Living well, within the limits of our planet’. This programme is intended to help guide EU action on the environment and climate change up to and beyond 2020 based on the following vision: ‘In 2050, we live well, within the planet’s ecological limits. Our prosperity and healthy environment stem from an innovative, circular economy where nothing is wasted and where natural resources are managed sustainably, and biodiversity is protected, valued and restored in ways that enhance our society’s resilience. Our low-carbon growth has long been decoupled from resource use, setting the pace for a safe and sustainable global society.’
• Climate-ADAPT: Adaptation in EU policy sectors
  Overview of EU sector policies in which mainstreaming of adaptation to climate change is ongoing or explored
• Climate-ADAPT: Country profiles
  Overview of activities of EEA member countries in preparing, developing and implementing adaptation strategies
• DG CLIMA: Adaptation to climate change
  Adaptation means anticipating the adverse effects of climate change and taking appropriate action to prevent or minimise the damage they can cause, or taking advantage of opportunities that may arise. It has been shown that well planned, early adaptation action saves money and lives in the future. This web portal provides information on all adaptation activities of the European Commission.
• Directive 2007/60/EC of the European Parliament and of the Council on the assessment and management of flood risks
  Directive 2007/60/EC of the European Parliament and of the Council of 23 October 2007 on the assessment and management of flood risks (Text with EEA relevance) OJ L 288, 06/11/2007, p. 27–34
• EU Adaptation Strategy Package
  In April 2013, the European Commission adopted an EU strategy on adaptation to climate change, which has been welcomed by the EU Member States. The strategy aims to make Europe more climate-resilient. By taking a coherent approach and providing for improved coordination, it enhances the preparedness and capacity of all governance levels to respond to the impacts of climate change.
• Evaluation of the EU Adaptation Strategy Package
  In November 2018, the EC published an evaluation of the EU Adaptation Strategy. The evaluation package comprises a Report on the implementation of the EU Strategy on adaptation to climate change (COM(2018)738), the Evaluation of the EU Strategy on adaptation to climate change (SWD(2018)461), and the Adaptation preparedness scoreboard Country fiches (SWD(2018)460). The evaluation found that the EU Adaptation Strategy has been a reference point to prepare Europe for the climate impacts to come, at all levels. It emphasized that EU policy must seek to create synergies between climate change adaptation, disaster risk reduction efforts and sustainable development to avoid future damage and provide for long-term economic and social welfare in Europe and in partner countries. The evaluation also suggests areas where more work needs to be done to prepare vulnerable regions and sectors.
• Guidance for Reporting under the Floods Directive (2007/60/EC)
  Guidance Document No. 29 A compilation of reporting sheets adopted by Water Directors Common Implementation Strategy for the Water Framework Directive (2000/60/EC)

Methodology

Methodology for indicator calculation

Trends in river floods are calculated based on the annual flood discharge of all rivers included in the European Flood Database.

Future changes in the risk of river floods in Europe have been simulated using the hydrological model Lisiflood, driven by an ensemble of climate simulations. Of particular interest is the frequency analysis of flood peaks above the 100-year flood level, which is the average protection level of the European river network (albeit with significant differences).

Methodology for gap filling

Not applicable.

Methodology references

• Alfieri et al. (2015): Global warming increases the frequency of river floods in Europe. Alfieri, L., Burek, P., Feyen, L. and Forzieri, G., 2015, 'Global warming increases the frequency of river floods in Europe', Hydrology and Earth System Sciences 19(5), 2247–2260 (DOI: 10.5194/hess-19-2247-2015).
• Blöschl et al., 2019: Changing climate both increases and decreases European river floods. Blöschl, G., et al., 2019, ‘Changing climate both increases and decreases European river floods’,Nature573(7772), pp. 108-111 (DOI: 10.1038/s41586-019-1495-6).

Data specifications

EEA data references

• No datasets have been specified here.

External data references

• Projected change in river floods with a return period of 100 years
• European Floods Database

Data sources in latest figures

Uncertainties

Methodology uncertainty

Not applicable.

Data sets uncertainty

The data required for the indicator are those on river flow, in particular data on extreme high flows. Time series can be observed or simulated for historical periods and can be projected for future time windows, taking into account climate change and potentially also other drivers of change, such as land use changes.

River flow is influenced by rainfall run-off and by hydromorphological changes of the river bed, e.g. through river engineering. Furthermore, homogeneous time series are generally shorter than those for meteorological data. Therefore, substantially more time may be required before statistically significant changes in hydrological variables can be observed, especially with respect to extreme and exceptional events, such as floods.

Notwithstanding recent improvements of climate models that simulate large-scale patterns of precipitation and extreme events, projections of changes in precipitation extremes at catchment and local scales remain uncertain. Projections of small river floods are plagued by the highest levels of uncertainty, as they often depend on changes in localised extreme events.

Rationale uncertainty

No uncertainty has been specified