Indicator Specification

River flow drought

Indicator Specification
  Indicator codes: CLIM 018
Published 20 Nov 2012 Last modified 20 Dec 2016
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This page was archived on 20 Dec 2016 with reason: Other (New version data-and-maps/indicators/river-flow-drought-2 was published)
Water scarcity and drought events in Europe Projected change in minimum river flow with return period of 20 years

Assessment versions

Published (reviewed and quality assured)
  • No published assessments


Justification for indicator selection

Lack of water has severe consequences for Europe’s citizens and most economic sectors, including agriculture, energy production and industry. An intense drought throughout the Iberian Peninsula during 2004-05, for example, led to a 40% decline in cereal production, whilst low rainfall in 2006 led to a 30% fall in agricultural production in Lithuania,  with an estimated loss of EUR 200 million. In Slovenia, direct losses attributable to drought in 2003 are estimated to be around EUR 100 million. Furthermore, lack of water detrimentally impacts freshwater ecosystems including vegetation, fish, invertebrates and riparian bird life. Diminished flow also strongly impacts water quality by reducing the ability of a river to dilute pollutants.

Electricity production has already been significantly reduced in various locations in Europe during very warm summers due to limitations of cooling water supply from rivers. Dry periods can also seriously impact the production of hydropower, e.g. in the case of Catalunia where the 2003-2007 drought caused a hydropower reduction of over 40%.

Scientific references

Indicator definition

  • Water scarcity and drought events in Europe
  • Projected change in minimum river flow with return period of 20 years


  • [dimensionless]
  • % 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/2013/0216 final */ and a number of supporting documents. One of the objectives of the EU Adaptation Strategy is Better informed decision-making, which should occur through Bridging the knowledge gap and Further developing Climate-ADAPT as the ‘one-stop shop’ for adaptation information in Europe. Further objectives include Promoting action by Member States and Climate-proofing EU action: promoting adaptation in key vulnerable sectors. Many EU Member States have already taken action, such as by adopting national adaptation strategies, and several have also prepared action plans on climate change adaptation.

The European Commission and the European Environment Agency have developed the European Climate Adaptation Platform (Climate-ADAPT, 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.


No targets have been specified.

Related policy documents

  • 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.
  • 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.

Key policy question

What is the trend in minimum river flow across Europe?



Methodology for indicator calculation

Water scarcity and drought events in Europe during the last decade are shown based on Tallaksen, 2007, personal communication. For the projections, an ensemble was applied consisting of simulations from 12 climate experiments conducted within the ENSEMBLES project, forced by the SRES A1B emission scenario for the period 1961-2100. Prior to driving the hydrological model LISFLOOD, climate simulations are corrected for bias in precipitation and temperature using a Quantile Mapping (QM) method.

Methodology for gap filling

Not applicable

Methodology references


Data specifications

EEA data references

  • No datasets have been specified here.

External data references

Data sources in latest figures



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.

The main data sources for European-wide studies of extreme hydrological events and their changes are global databases for natural disasters. These include general impact-oriented disaster databases such as EM-DAT ([1]) maintained by the Centre for Research on the Epidemiology of Disasters (CRED) and the NatCatService ([2]) maintained by Munich Re, as well as specific mostly event-oriented databases, such as the Dartmouth Flood Observatory ([3]). Some of the limitations of these databases included the use of thresholds for inclusion of an event, which may exclude smaller events with a significant regional impact, changes over time in the comprehensiveness of the coverage (see below), and privacy issues related to detailed data collected by the insurance industry. Improvements of these datasets are planned in coming years. The available data is currently evaluated, for example in the ongoing emBRACE project ([4]). A more detailed and comprehensive event-oriented database that also includes events without any (major) damages would be needed to separate the effect of climate change from socio-economic changes.

The reporting of flood and drought events has generally improved during the past few decades as a result of improvements in data collection and flows of information. As a result, it is often difficult to identify whether an increase in reported flood events (or their impacts) over time is due mostly to improvements in data collection or to actual changes in these events. Furthermore, river flood records are usually sourced from different institutions and often collected using a wide range of different assessment methods and rationales, which may have changed over time. This multitude of sources limits the comparability of key attributes associated with such events (e.g. economic losses, human casualties) across space and time.

As part of the preliminary flood risk assessment for the European directive on the assessment and management of flood risks (2007/60/EC) ([5]), EU Member States will give an overview of significant past floods. In addition, a European flood impact database could bring together publicly available inventories of flood events. At the national/regional level, such an inventory would be particularly useful to provide accurate data and assessments which would serve as a basis for disaster prevention. At the European level, these inventories could assist in tracking the trends in flood-disaster losses, and in mitigation programmes monitoring and obtaining a clearer picture of the linkages between climate change and floods and flood losses.

Further information on uncertainties is provided in Section 1.7 of the EEA report on Climate change, impacts, and vulnerability in Europe 2012 (

[1] See online.

[2] See online.

[3] See online.

[4] See online.

[5] See online.

Rationale uncertainty

No uncertainty has been specified

Further work

Short term work

Work specified here requires to be completed within 1 year from now.

Long term work

Work specified here will require more than 1 year (from now) to be completed.

General metadata

Responsibility and ownership

EEA Contact Info

Wouter Vanneuville


European Environment Agency (EEA)


Indicator code
CLIM 018
Version id: 2

Frequency of updates

Updates are scheduled every 4 years


DPSIR: Impact
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)


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