Use of freshwater resources

Indicator definition

The water exploitation index (WEI) is the mean annual total abstraction of freshwater divided by the mean annual total renewable freshwater resource at the country level, expressed in percentage terms.

Units

Water exploitation index - WEI (%); water abstraction for irrigation, public water supply, manufacturing industry and energy cooling  (mio. m³ per year).

Policy context and targets

Context description

Achieving the objective of the EU's Sixth Environment Action Programme (2001-2010), to ensure that rates of extraction from water resources are sustainable over the long term, requires monitoring of the efficiency of water use in different economic sectors at the national, regional and local level. The WEI is part of the set of water indicators of several international organisations such as UNEP, OECD, EUROSTAT and the Mediterranean Blue Plan. There is an international consensus about the use of this indicator.

The indicator describes how the total water abstractions put pressure on water resources identifying those countries having high abstractions in relation to their resources and therefore prone to suffer water stress. The changes in WEI help to analyse how the changes in abstractions impact on the freshwater resources by adding pressure to them or by making them more sustainable.

Targets

There are no specific quantitative targets directly related to this indicator. However, the Water Framework Directive (2000/60/EC) requires countries to promote sustainable use based on long-term protection of available water resources and ensure a balance between abstraction and recharge of groundwater, with the aim of achieving good groundwater status by 2015.

The warning threshold for the water exploitation index which distinguishes a non-stressed from a stressed region is around 20 %. Severe water stress can occur where the WEI exceeds 40 %, indicating strong competition for water but not necessarily enough extraction to trigger frequent water crises (see methodology section for further discussion of threshold values).

Related policy documents

• Sixth Environment Action Programme (decision No 1600/2002/EC)
  DECISION No 1600/2002/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 22 July 2002 laying down the Sixth Community Environment Action Programme
• Water Framework Directive (WFD) 2000/60/EC
  Water Framework Directive (WFD) 2000/60/EC: Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for Community action in the field of water policy.

Methodology

Methodology for indicator calculation

Calculation of water exploitation index

1) The latest data from Eurostat (updated 2005/07/22) on total water abstraction (totABS) and long term annual average renewable resource (LTAA) have been extracted.

2) For each country quality assured 1990 and 2002 totABS values and LTAA value have been established. In some cases suspicious values has been checked against national sources.

3.Once the data series are complete (data close 1990 and 2002), the WEI is calculated, by country and year, as the ratio of total water annual abstraction to the long-term annual average available volume (Ltaa) of freshwater resources, expressed in percentage terms.

WEI = totABS / LTAA x 100

Where: totABS = total annual freshwater abstraction for all uses;  LTAA = long term annual average of freshwater resources, where data are averaged over a period of at least 20 consecutive years. Unit = %

The warning threshold for the water exploitation index which distinguishes a non-stressed from a stressed region is around 20 % (Raskin et al. 1997). Severe water stress can occur where the WEI exceeds 40 %, indicating strong competition for water but not necessarily enough extraction to trigger frequent water crises. Some experts argue that 40 % is too low a threshold, and that water resources could be used much more intensively, up to a 60 % threshold. Others argue that freshwater ecosystems cannot remain healthy if the waters in a river basin are abstracted as intensely as indicated by a WEI in excess of 40 % (Alcamo et al., 2000).

Sub-indicators water abstraction by sectors

1) The latest data from Eurostat on total water abstraction by sector from the table Annual water abstraction by source and by sector (mio3/year) have been extracted

2) Then their are established quality controlled values for each country and sector for 1990 and 2002

3) Data are then sorted for the four European regions and the sums are calculated for each region.

4) Then the four bar charts have been produced.

Methodology for gap filling

When data values from Eurostat are not available for 1990 or 2002, ETC Water has generally used the nearest value for graph production (e.g. if no 1990 data, data from 1989, 1991 or 1992 has been used). If no data close to (generally +/- 3 years) the start or end year - the country has not been included into graphs or region sums. In case of deviation the exact year for the country is listed in the diagram notes.

Methodology references

• Raskin et al. 1997 Raskin, P., Gleick, P.H., Kirshen, P., Pontius, R. G. Jr and Strzepek, K. ,1997. Comprehensive assessment of the freshwater resources of the world. Stockholm Environmental Institute, Sweden. Document prepared for UN Commission for Sustainable Development 5th Session 1997 - Water stress categories are described on page 27-29.
• Alcamo et al. 2000 Alcamo, J., Henrich, T., Rosch, T., 2000. World Water in 2025 - Global modelling and scenario analysis for the World Commission on Water for the 21st Century. Report A0002, Centre for Environmental System Research, University of Kassel, Germany

Uncertainties

Methodology uncertainty

Data at the national level cannot reflect water stress situations at the regional or local level. The indicator does not reflect the uneven spatial distribution of resources and may therefore   mask regional or local risks of water stress.

Caution should be used when comparing countries, because of different definitions and procedures for estimating water use (e.g. some include cooling water, other do not) and freshwater resources, in particular internal flows. Some sectoral abstractions, such as cooling water included in the industrial abstraction data, do not correspond to the specified uses.

Sectoral use of water does not always reflect the relative importance of the sectors in the economy of one country. It is rather an indicator of on which sectors the environmental measures need to focus in order to enhance the protection of the environment.

Data sets uncertainty

Data need to be considered with reservation due to the lack of common European definitions and procedures for calculating water abstraction and freshwater resources. Current work is being carried out between EUROSTAT and EEA to standardise definitions and methodologies for data estimation.

Data are not available for all the countries considered, especially for 2000 and 2002, and the data series from 1990 are not complete. There are gaps in water use in some years and for some countries, particularly in the Nordic and the southern accession countries.

Accurate assessments that take climatic conditions into account would require the use of more disaggregated data at the spatial and geographical level.

Rationale uncertainty

Better indicators of the evolution of freshwater resources in each country are needed (for example by using information on trends in discharges at some representative gauging stations per country). If groundwater abstractions are considered separately from surface water abstractions, it would be necessary to have some indicators on the evolution of the groundwater resource (for example by using information on the head levels of selected piezometers per country). Better estimates of water abstraction could be developed by considering the uses involved in each economic sector.

Spatial level: There are notable differences between water uses in countries. Thus the assessment of the indicators should be based at national scale as a minimum requirement, although it would be preferable to have data at basin scale if available.