Use of freshwater resources

Indicator Specification
Indicator codes: CSI 018 , WAT 001
Created 04 Jun 2015 Published 21 Mar 2016 Last modified 28 Jun 2018
14 min read
The WEI+ provides a measure of the total water use as a percentage of the renewable freshwater resources for a given territory and time scale. The WEI+ is an advanced and geo-referenced implementation of the WEI. It quantifies how much water is monthly or seasonally abstracted and how much water is returned after use to the environment via basins. The difference between water abstraction and return is regarded as water use.

Assessment versions

Published (reviewed and quality assured)

Rationale

Justification for indicator selection

Monitoring the efficiency of water use is important for the protection, conservation and enhancement of the EU’s natural capital. It also contributes to improving resource efficiency, which is included as an objective of the EU's 7th EAP to 2020.

The WEI+ is a water scarcity indicator that provides information on the level of pressure that human activity exerts on the natural water resources of a territory. This helps to identify those areas prone to problems related to water stress (Faergemann, 2012). The purpose of implementing the WEI+ at spatial (e.g. sub-basin or river basin) and temporal (monthly or seasonal) scales, which are finer than annual averages at the country scale, is to better capture the balance between renewable water resources and water use (see Conceptual model of WEI+ computation).

Scientific references

Indicator definition

The WEI+ provides a measure of the total water use as a percentage of the renewable freshwater resources for a given territory and time scale.

The WEI+ is an advanced and geo-referenced implementation of the WEI. It quantifies how much water is monthly or seasonally abstracted and how much water is returned after use to the environment via basins. The difference between water abstraction and return is regarded as water use.

Units

WEI+ values are given as percentages, i.e. water use as a percentage of renewable water resources. Absolute water volumes are presented as millions of cubic meters (million m3 or hm3).

 

Policy context and targets

Context description

The objective of the EU's 7th EAP to 2020 is to ensure the protection, conservation and enhancement of the EU’s natural capital and to improve resource efficiency. Monitoring the efficiency of water use in different economic sectors at national, regional and local levels is necessary to achieve this. The WEI is part of the set of water indicators published by several international organisations, such as the United Nations Environment Programme (UNEP), the Organisation for Economic Co-operation and Development (OECD), Eurostat and the Mediterranean Blue Plan. There is an international consensus about the use of this indicator for assessing the pressure of the economy on water resources, i.e. water scarcity.

The WEI+ is an advanced version of the WEI, which better addresses regional and seasonal aspects of water scarcity. In addition, it also takes water use (water abstraction minus water returned) into account. The indicator describes how total water use exerts pressure on water resources. It identifies areas (e.g. sub-basins or river basins) that have high abstraction levels on a seasonal scale in relation to the resources available and that are therefore prone to water stress. Changes in WEI+ values allow analyses of how changes in water use affect freshwater resources, i.e. by putting them under pressure or by making them more sustainable.

Targets

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

The 7th EAP aims to ensure that, by 2020, stress on renewable water resources is prevented or significantly reduced in the EU (EU, 2013). The EU’s Roadmap to a Resource Efficient Europe (EC, 2011) also includes the goal that, by 2020, ‘water abstraction should stay below 20 % of available renewable freshwater resources’. However, no particular spatial and temporal context (analytical unit) is given in this roadmap.

Regarding WEI+ thresholds, it is important that agreement is reached on how to delineate non-stressed and stressed areas.  Raskin et al. (1997) suggested that a WEI value of more than 20 % should be used to indicate water scarcity, whereas a value of more than 40 % would indicate severe water scarcity. These thresholds are commonly used in scientific studies (Alcamo et al., 2000).  Smakhtin et al. (2004) suggested that a 60 % withdrawal from the annual total runoff would cause environmental water stress.  Similarly, the Food and Agriculture Organization of the United Nations (FAO) applies a value of above 25 % of water abstraction as an indication of water stress and of above 75 % as an indication of serious water scarcity (FAO, 2017). Since no formally agreed thresholds are available for assessing water stress conditions across Europe, in the current assessment, the 20 % WEI+ threshold proposed by Raskin at al. (1997) is considered to distinguish stressed from non-stressed areas, while a value of 40 % is used as the highest threshold for mapping purposes.

 

 

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.’
  • Addressing the challenge of water scarcity and droughts in the European Union
    EC (2007). Communication from the Commission to the Council and the European Parliament, Addressing the challenge of water scarcity and droughts in the European Union. Brussels, 18.07.07, COM(2007)414 final.
  • Roadmap to a Resource Efficient Europe
    Communication from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee of the Regions. Roadmap to a Resource Efficient Europe.  COM(2011) 571  
  • 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.

Key policy question

Is water scarcity decreasing in Europe?

Specific policy question

Water abstraction by source

Specific policy question

Water use by sectors

Methodology

Methodology for indicator calculation

The WEI+ is an advanced version of the water exploitation index. It is geo-referenced and developed for use on a seasonal scale. It also takes into account water abstraction (gross) and return (net abstraction) to reflect water use.

In 2011, a technical working group, developed under the Water Framework Directive Common Implementation Strategy, proposed the implementation of a regionalised WEI+. This differed from the previous approach by enabling the WEI+ to depict more seasonal and regional aspects of water stress conditions across Europe (See Conceptual model of WEI+ computation). This proposal was approved by the Water Directors in 2012 as one of the awareness-raising indicators.

The regionalised WEI+ is calculated according to the following formula:

WEI+ = (abstractions - returns)/renewable freshwater resources.

Renewable freshwater resources are calculated as 'ExIn + P - Eta - ΔS' for natural and semi-natural areas, and as 'outflow + (abstraction - return) - ΔS' for densely populated areas.

Where:  

ExIn = external inflow
P = precipitation
ETa = actual evapotranspiration

ΔS = change in storage (lakes and reservoirs)

outflow = outflow to downstream/sea.

It is assumed that there are no pristine or semi-natural river basin districts or sub-basins in Europe. Therefore, the formula 'outflow + (abstraction - return) - ΔS' is used to estimate renewable water resources.

Climatic data were obtained from the EEA Climatic Database, which was developed based on the ENSEMBLES Observation (E-OBS) Dataset (Haylock et al., 2008). The State of the Environment database was used to validate the aggregation of the E-OBS data to the catchment scale.

Streamflow data have been extracted from the EEA Waterbase — Water Quantity database. This database does not have sufficient spatial and temporal coverage yet. In order to fill the gaps, Joint Research Centre (JRC) LISFLOOD data (Burek et al., 2013) have been integrated into the streamflow data. The streamflow data cover Europe, in a homogeneous way, for the years 1990-2015 on a monthly scale.

Once the data series are complete, the flow linearisation calculation is implemented, followed by a water asset accounts calculation, which is done in order to fill the data for the parameters requested for the estimation of renewable water resources. The computations are implemented at different scales independently, from sub-basin scale to river basin district scale. 

Overall, annually reported data are available for water abstraction by source (surface water and groundwater) and water abstraction by sector with temporal and spatial gaps. Gap-filling methods are applied to obtained harmonised time series.

No data are available at the European scale on 'Return'. Urban waste water treatment plant data, the European Pollutant Release and Transfer Register (E-PRTR) database, Eurostat population data, JRC data on the crop coefficient of water consumption, satellite observed phenology data have been used as proxy to quantify the water demand and water use by different economic sectors. Eurostat tourism data (Eurostat, 2013b) and data on industry in production have been used to estimate the actual water abstraction and return on a monthly scale. Where available, state of the environment and Eurostat data on water availability and water use have also been used at aggregated scales for further validation purposes. 

Once water asset accounts are implemented according to the United Nations System of Environmental Accounting Framework for Water (2012), the necessary parameters for calculating water use and renewable freshwater water resources are harvested.

Following this, bar and pie charts are produced, together with static and dynamic maps.

Methodology for gap filling

For each parameter of water abstraction, return and renewable freshwater resources, primarily data from the Waterbase — Water Quantity database have been used. Eurostat, OECD and Aquastat (FAO) databases have also been used to fill the gaps in the data sets. Furthermore, the statistical office websites of all European countries have each been visited not only once but several times to get the most up-to-date data from these national open sources. Despite this, some gaps still needed to be filled by applying certain statistical or geospatial methodologies (See reference data sources for gap filling and modulation coefficients).

LISFLOOD data from the JRC have been used to gap fill the streamflow data set (See reference data sources for gap filling and modulation coefficients). The spatial reference data for the WEI+ are the European Catchments and Rivers Network System (Ecrins) data (250-m vector resolution). Ecrins is a vector spatial data set, while LISFLOOD data are in 5-km raster format. In order to fill the gaps in the streamflow data, centroids of the LISFLOOD raster have been identified as fictitious (virtual) stations. The topological definition of the drainage network in Ecrins has been used to match the most relevant and nearest fictitious LISFLOOD stations with EEA-Eionet stations and the Ecrins river network. After this, the locations of stations between Eionet and LISFLOOD stations were compared and overlapping stations were selected for gap filling. For the remaining stations, the following criteria were adhered to: fictitious stations had to be located within the same catchment as the Eionet station and have the same main river segment; in addition, both stations had to show a strong correlation.

A substantial amount of gap filling has been performed in the data on water abstraction for irrigation. First, a mean factor between utilised agricultural areas and irrigated areas has been used to fill the gaps in the data on irrigated areas. Then, a multiannual mean factor of water density (m3/ha) in irrigated areas per country has been used to fill the gaps in the data on water abstraction for irrigation.

The gaps in the data on water abstraction for manufacturing and construction have been filled by using Eurostat data on production in industry (Eurostat [sts_inpr_a]) and the E-PRTR database with the methodologies in the best available techniques reference document (BREF) to convert the production level into the volume of water.

Methodology references

  • 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
  • EC 2012a Preparatory Action, Development of Prevention Activities to halt desertification in Europe, Service Contract to contribute to the building of Water and Ecosystem accounts at EU level. Part 1.
  • EC 2012b  Preparatory Action, Development of Prevention Activities to halt desertification in Europe, Service Contract to contribute to the building of Water and Ecosystem accounts at EU level. Part 2.
  • Kurnik, B., Louwagie, G., Erhard, M., Ceglar, A. and Bogataj Kajfež, L., 2014. Analysing Seasonal Differences between a Soil Water Balance Model and In-Situ Soil Moisture Measurements at Nine Locations Across Europe. Environmental Modeling & Assessment 19(1), pp. 19–34.
  • 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.
  • Smakhtin, V., Revanga, C. and Doll, P. 2004. Taking into account environmental water requirement in global scale water resources assessment. Comprehensive Assessment Research Report 2. Colombo, Sri Lanka: Comprehensive Assessment Secretariat. ISBN 92-9090-542-5
  • ETC ICM, 2015. CSI 018 Use of freshwater resources in Europe (WAT01). Supplementary document to the draft indicator sheet.  
  • Burek, P., Kniff van der, J., Roo de, A. 2013 LISFLOOD, distributed water balance and flood simulation model revised user manual 2013. European Commission Joint Research Centre Institute for the Protection and the Security of the Citizen. Luxembourg. ISBN: 9789279331909 9279331906  
  • Land Productivity Dynamics in Europe Towards a Valuation of Land Degradation in the EU Cherlet M., Ivits E., Sommer S., Tóth G.,Jones A., Montanarella L., Belward A.
  • Newly created MethodologyReference
  • FAO, 2017. Step-by-step monitoring methodology for indicator 6.4.2 Level of water stress: freshwater withdrawal in percentage of available freshwater resources.  

Data specifications

EEA data references

External data references

Data sources in latest figures

Uncertainties

Methodology uncertainty

Reported data on water abstraction and water use do not have sufficient spatial or temporal coverage. Therefore, estimates based on country coefficients are required to assess water use. First, water abstraction values are calculated and, second, these values are compared with the production level in industry and in relation to tourist movements in order to approximate actual water use for a given time resolution. This approach cannot be used to assess the variations (i.e. the resource efficiency) in water use within the time series. 

Spatial data on lakes and reservoirs are incomplete. On the other hand, as reference volumes for reservoirs, lakes and groundwater aquifers are not available, the water balance can be quantified as only a relative change, and not the actual volume of water. This masks the actual volume of water stored in, and abstracted from, reservoirs. Thus, the impact of the residence time, between water storage and use, in reservoirs is unknown.

The sectoral use of water does not always reflect the relative importance of the sectors to the economy of a given country. It is, rather, an indicator that describes which sectors environmental measures should focus on in order to enhance the protection of the environment. A number of iterative computations based on identified proxies are applied to different data sets, i.e. urban waste water treatment plant data, E-PRTR data, Eurostat population data, JRC data on the crop coefficient of water consumption and satellite-observed phenology data have been used as proxies to quantify the water demand and water use by different economic sectors. This creates a high level of uncertainty in the quantification of water return from the economic sectors, thus also leads to uncertainty with regard to the 'water use' component.

In order to distribute population data across Europe, the Geostat 2011 grid data set from Eurostat was used. Then, further aggregations were performed in the spatial dimension to give the sub-basin and functional river basin district scales of Ecrins spatial reference data. The population within the time frame of one calendar year is regarded as stable. Variations are taken into account only for the annual scale. Deviations from officially reported data are expected because of the nature of the methodological steps followed.

The tourist data used were provided by Eurostat and relate to the nights spent per NUTS2 region, on the monthly scale, in accommodation establishments. Because of the aggregation/disaggregation steps followed, deviations from officially reported data are expected. The tourist population was included in the calculation as additional to the stable (local resident) population.

Where monthly data were not available, Eurostat tourist data (Eurostat, 2013b), data on industry in production (Eurostat [sts_inpr_a]) and JRC satellite-observed phenology data were used to estimate the actual water abstraction and return on a monthly scale.

A validation of the results has been performed by comparing the estimates with reported data where feasible. Some contradictory results have been observed. For instance, the desalination of sea water is one of the methods used to meet the water demands of Cyprus, Malta and Spain. Based on this use of desalinated water, the actual WEI would be around 35-40 % for Malta. However, as desalinated water is not included in the computation of renewable freshwater resources, the WEI+ for Malta is around 100 %. Similarly, because of some technical issues with the reported data on streamflow, the WEI+ could not be computed for Cyprus. Therefore, the results for Cyprus were excluded from the overall assessment. The average WEI reported for Cyprus is 73.1 % for the years 2009-2013 under Water Framework Directive river basin management plan reporting.

A high degree of inconsistency between sub-basin and functional river basin district scales has been observed for the Guadiana river basin. The estimated WEI+ for Guadiana is 131 % for summer 2015, whereas the estimated WEI+ values for its sub-basins for the same period are as follows: 75 % for Upper Zancara, 41 % for Zujar and 48 % for Ardilla. This inconsistency seems to be related to the computations for the aggregation from sub-basin to functional river basin district for this basin. The value will be corrected once this technical problem has been solved. 

 

 

Data sets uncertainty

Data are very sparse on some particular parameters of the WEI+. For instance, current streamflow data reported by the EEA member countries to the WISE SoE — Water Quantity database do not have sufficient temporal or spatial coverage to provide a strong enough basis for estimating renewable water resources for all of Europe.  Such data are not available elsewhere at the European level either. Therefore, JRC LISFLOOD data are used intesively as surrogates  (see availability on streamflow data). 

Data on water abstraction by economic sectors have better spatial and temporal coverage. However, the representativeness of data for some sectors is also poor, such as the data on water abstraction for mining.  In addition to the WISE SoE — Water Quantity database, intensive efforts to compile data from open data sources such as Eurostat, OECD, Aquastat (FAO) and national statistical offices have also been made (see share of surrogate data vs reported data on water abstraction).

Quantifying water exchanges between the environment and the economy is, conceptually, very complex. A complete quantification of the water flows from the environment to the economy and, at a later stage, back to the environment, requires detailed data collection and processing, which have not been done at the European level. Thus, reported data have to be used in combination with modelling to obtain data that can be used to quantify such water exchanges, with the purpose of developing a good approximation of 'ground truth'. However, the most challenging issue is related to water abstraction and water use data, as the water flow within the economy is quite difficult to monitor and assess given the current lack of data availability. Therefore, several interpolation, aggregation or disaggregation procedures have to be implemented at finer scales, with both reported and modelled data. Main consequences of data set uncertainty are the followings;  

  1. The Danube river basin is accounted for as a single district in Ecrins, so it aggregates a lot of regional and national information.  

  2. The water accounts and WEI+ results have been implemented in the EEA member and Western Balkan countries. However, regional data availability was an issue for some river basins (e.g. in Cyprus, the Jarft in Poland, North West and North Eastern river basins in the United Kingdom, the Kymijoki river basin in the Gulf of Finland, Gran Canarias of Spain and some Icelandic and Turkish river basins), which had to be removed from the assessment. 

Rationale uncertainty

Because of the aggregation procedure used, slight differences exist between sub-basin and river basin district scales for total renewable water resources and water use.

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

Nihat Zal

Ownership

European Environment Agency (EEA)

Identification

Indicator code
CSI 018
WAT 001
Specification
Version id: 2

Frequency of updates

Updates are scheduled once per year

Classification

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

Related content

Data references used

Data used

European catchments and Rivers network system (Ecrins) European catchments and Rivers network system (Ecrins) Version 1, Jun. 2012 - Ecrins is acronym for European catchments and Rivers network system. It is a geographical information system of the European hydrographical systems with a full topological information. Ecrins is a composite system made from the CCM developed by the JRC, Corine land Cover, WFD reporting elements, etc. It is organised from a layer of 181,071 “functional elementary catchments (FECs)” which average size is ~62 km2, fully connected with explicit identifier (ID) relationships and upstream area. Catchments are grouped as sub-basins, river basin districts (actual and functional to meet hydrographical continuity). The catchments are as well organised according to their sea shore of emptying to meet Marine Strategy delineations. Catchments are drained by 1,348,163 river segments, sorted as “main drains” (connecting together the FECs) and secondary drains (internal to a FEC). river segments mimic the natural drainage, however fulfilling the topological constraint of “0,1 or 2 upstreams, single or 0 downstream”. Each segment is populated with distance to the sea, to ease further processing. They are connected to elementary catchments and nodes documented with altitude. Segments are as well documented with a “dummy river code”, fully populated that earmark each segment with the most distant to the outlet in each drainage basin and, everywhere this has been possible, with a “true river” ID based on river naming. A layer of lakes and dams has been elaborated. Lakes polygons (70,847) are taken from Corine Land cover , WFD Art. 13 and in some cases, from CCM “water layer”. Lakes inlets and outlets are set with the segment ID and where relevant, the dams making the lake is documented. All lakes which depths and volume was found have been updated. Version 1.0 here presented still contain some topological errors (e.g. incorrect segment branching), because inaccurate geometry. They are noted and a correction procedure is underway.

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