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Indicator Assessment
Despite an estimated decrease of total water abstraction by 19 % since 1990 in Europe, the milestone set in the EU resource efficiency roadmap — i.e. a water abstraction should stay below 20 % of available renewable water resources in Europe — has not been achieved in 36 river basins corresponding to 19 % of Europe’s territory in summer 2015.
Around 30 % of the total European population was exposed to water scarcity conditions in summer 2015 compared to 20% in 2014, mainly living in densely populated European cities, agriculture-dominated areas of southern Europe and small Mediterranean islands.
From 2000 to 2015, in the EU-28, there was an absolute decoupling of water abstraction (-9 %) and the gross value added generated from all economic sectors (+53 %).
A rapid increase (+11%) has been observed in bottled water consumption from 2010, particularly in southern and western Europe.
Water exploitation index plus (WEI+) for river basin districts (1990-2015)
Note:
This interactive map gives a European overview of water stress conditions. The information presented may deviate from that available in the EEA member countries and cooperating countries, particularly for those countries where data availability is insufficient in the WISE SoE - Water quantity database (WISE 3).
Data on hydro-climatic variables were aggregated from a daily to a monthly scale. Water abstraction data were taken from WISE 3 (annual resolution at the national scale), although there are large gaps in the time series. Therefore, intensive gap filling was performed on water abstraction data and proxies were used to disaggregate the data from the national to the sub-basin scale.
Information on water use was mainly modelled on the UWWTP capacities, the E-PRTR database and the Eurostat Population change dataset (online data code [demo_gind]) among others. See the methodology chapter for further explanation of gap filling, and spatial and temporal disaggregation, and the data uncertainties chapter for current data availability.
This interactive map allows users to explore changes over time in water abstraction by source, water use by sector and water stress level at sub-basin or river basin scale. The WEI+ has been estimated as the quarterly average per river basin district for the years 1990-2015, as defined in the European catchments and rivers network system (ECRINS). The ECRINS delineation of river basin districts differs slightly from that defined by Member States under the Water Framework Directive. The Ecrins delineation is used instead of the WFD because it contains geospatial information on Europe’s hydrographical systems with full topological information enabling flow estimation between upstream and downstream basins, as well as integration of economic data collected at NUTS or country level.
In addition to using the WISE SoE - Water quantity database, comprehensive manual data collection was performed by accessing all open sources (Eurostat, OECD, FAO), including national statistical offices of the countries. This was done because of the temporal and spatial gaps in the data on water abstraction. Moreover, a large part of the stream flow data from LISFLOOD has also been substantially updated by the Directorate-General Joint Research Centre. Similarly, a comprehensive update with climatic parameters has been performed by the EEA based on the E-OBS dataset. Therefore, the time series of the WEI+ presented in the current version might be slightly different for some basins compared with the previous version.
Water scarcity is driven primarily by two factors: climate, which controls the availability of renewable freshwater resources and seasonality in water supply, and water demand, which is largely driven by population and related economic activities.
The water exploitation index plus (WEI+) aims to illustrate pressure on renewable water resources of a defined territory (river basin, sub-basin etc.) in a given period (e.g. seasonal, annual) as a consequence of water use for human activities. Values above 20 % indicate that water resources are under stress, and above 40 % indicate severe stress and a clearly unsustainable use of freshwater resources (Raskin et al., 1997).
The EU's Seventh Environment Action Programme (7th EAP) aims to ensure that stress on renewable water resources is prevented or significantly reduced by 2020 (EU, 2013). The EU’s Roadmap to a Resource Efficient Europe (EC, 2011) also includes a goal for 2020, namely that ‘water abstraction should stay below 20 % of available renewable freshwater resources’. However, no particular spatial or temporal context (analytical unit) is given in the roadmap. European-scale estimations of water scarcity or water abstraction are likely to underestimate actual water stress levels and would thus be misleading. Instead, estimations of the proportional area affected by water scarcity conditions (either seasonally or throughout an entire year) may better capture the actual level of water stress on the continental scale.
While freshwater is relatively abundant in Europe in terms of the long-term, annual average (3 500 m3/per inhabitant), the availability of renewable freshwater resources and the intensity of socio-economic activities are highly variable and unevenly distributed, leading to major differences in water stress levels and renewable water resources over seasons and across the continent e.g. from 11 000 m3/per inhabitant in some parts of northern Europe to around 100 m3/per inhabitant in some densely populated southern river basins, for instance in Maltese RBD (Environment and Resources Authority, 2015). Renewable water resources also varied considerably among different parts of Europe in the 1990-2015 period, decreasing from 2 300 to 1 800 m3/inhabitant in southern Europe (due to a decrease in net precipitation and an increase in population pressure) and increasing from 1 200 to 2 200 m3/inhabitant in eastern Europe (for the opposite reasons). In western Europe, renewable freshwater resources range from 200 to 2 500 m3/inhabitant, because of an uneven population distribution, concentrated in river basins.
In 2015, the European annual average of renewable water resources is estimated to have been around 3 100 m3/inhabitant, with the highest values in northern European basins (650 000 m3/inhabitant in the Vuoksi River Basin, Finland) and the lowest in southern European and densely populated western basins (105 m3/inhabitant in Attica, Greece).
While renewable freshwater resources are controlled by climate, water scarcity emerges because of excessive use of water for socio-economic activities. Southern and some densely populated basins of Europe experience incessant water scarcity, at least for one season each year. Water scarcity has also been expanding to affect basins that would not normally be expected to experience water scarcity (e.g. the Elbe basin in summer 2015 and the Black Sea basin in 2007). Therefore, every year, there is high variability in areas experiencing water scarcity, either seasonally or throughout the entire year.
Water scarcity prevails in a number of European river basins, with different water stress levels, affecting around 15-25 % of total European territory. Water scarcity is frequently experienced in the southern Europe and in some river basins from western parts of Europe. More than half of southern Europe lives incessantly under water scarcity conditions particularly during the summer, of which agriculture and public water supply, including in relation to tourism, are the main drivers. For instance, because of very intensive irrigation in Middle Apennines and the Po Basin (Italy), Guadiana (Portugal and Spain), Segura (Spain), severe water stress is experienced throughout almost the entire year (see the map in Fig. 1).
Mediterranean islands such as the Balearic Islands, Sicily and Crete, are also under incessant and severe water stress conditions throughout the year, due to high pressure from tourism.
Water scarcity is not only limited to southern Europe. Because of high pressure on public water supplies and the use of water for cooling in energy generation, basins in western and northern Europe, e.g. the Ucker in the Czech Republic, Germany and Poland, the Zealand in Denmark and the Thames in the United Kingdom, may also experience water scarcity. However, overall water scarcity decreased in the 1990-2015 period thanks to improved water conveyancing, water savings in public supplies, efficiency gains in water use by industry and other reasons.
In summer 2015, renewable freshwater resources were 20 % less than the same period in 2014 because of a 10 % net precipitation deficit. These drought conditions exacerbated water scarcity in 34 river basin districts out of 116 RBD, which correspond to 20 % of European territory (see Figs 1 and 2 and the Policy context and targets section). It is estimated that around 30 % of total European inhabitants living in the vicinity of those 34 river basins were exposed to water scarcity conditions in summer 2015. However, because of the replenishment of renewable water resources during the winter months, the total area affected by this water scarcity decreased by 14 %.
In response to water scarcity, in many cases, water is transferred from other basins, which may affect natural hydrological cycles and negatively affect aquatic ecosystems in the donor basin.
The desalination of seawater is widely applied (e.g. in Cyprus, Malta and Spain) to meet high water demands under the limitation of renewable freshwater resources, but the process of evaporating the water requires high levels of energy and the brine effluent may harm marine and coastal ecosystems.
Substantial progress has been made towards reducing water abstraction, resulting in a decrease of around 19 % since 1990, in line with the 7th EAP objectives. However, the goal of water abstraction of less than 20 % of renewable water resources set in the Roadmap to a Resource Efficient Europe has not been achieved in all European basins, and does not look realistic in the short term. Hence, it remains uncertain whether or not significantly reducing water scarcity in Europe will be achieved by 2020.
The annual average of renewable freshwater resources is estimated to be around 1800 km3 for Europe (1990-2015) with high fluctuations over the years and seasons. This creates high pressure when fewer renewable water resources are available for a given season. The level of pressure also fluctuates per type of economic activity throughout the year. Agriculture and public water supplies put high pressure on groundwater resources in spring and summer, while the use of water for cooling in energy generation puts high pressure on rivers in winter and autumn. In 2015, renewable water resources were 10 % less than the multiannual average because of higher than average levels of actual evapotranspiration from land and water surfaces.
For decades, more dams and reservoirs have been constructed in Europe to reduce the potential impacts of a lack of water availability, particularly in summer months. For instance, since the 1950s, the number of reservoirs has increased by more than three times. The largest reservoir storage capacity is found in southern Europe (38 %), followed by western (30 %) and eastern Europe (20 %). However, dams and reservoirs change natural hydrological cycles, and fragment the longitudinal and latitudinal connectivity in rivers and riparian zones.
Positive developments have been improvements in water conveyancing, efficiency gains in water use and socio-economic transformations particularly in eastern Europe, which have resulted in an overall decrease of total water abstraction by 19 % since 1990. However, water abstraction for cooling in electricity generation in western and southern Europe and for households in southern Europe has slightly increased over the same period. A sharp decrease (by around 50 %) in water abstraction has been observed in eastern Europe due to the abandonment of old industrial installations, and also agricultural areas until 2010s (Alcantara et al, 2013; Hartvigsen, 2013).
In Europe, around 243 000 hm3 of water (long-term annual average for the 1990-2015 period) is annually abstracted as off-stream to meet the demand of the European economy. In 2015, about 232 000 hm3 of water was abstracted, 90 000 hm3 of which was used and 142 000 hm3 of which was returned back to the environment with a certain level of physical or chemical deterioration. Therefore, water use in 2015 was below the multiannual average. However, because of an estimated 10 % deficit in the net precipitation in 2015 compared with 2014, renewable water resources decreased by 20 % between 2014 and 2015. Therefore, in 2015, around 20 % of the total territory of Europe was affected by water scarcity conditions.
Around 40 % of total water use is accounted for by agriculture, followed by 28 % for cooling and 18 % for manufacturing and mining, while public water supplies account for 14 %.
At the regional level, overall, water use for cooling in electricity generation is the main pressure in western and eastern Europe, whereas agriculture is the most water-demanding sector in southern Europe and the manufacturing industry is most water-demanding in northern Europe.
Agriculture (irrigation)
Water plays a crucial role in agriculture . The major cause of water consumption in the agricultural sector is crop irrigation. Based on the annual average, agriculture accounts for 46 % of total water use in Europe, of which most is used in the southern basins where precipitation and soil moisture are not sufficient to satisfy crop water needs and production of some crop types would not be possible without irrigation. Irrigation is also used to increase crop yields. In general, vegetables and other crops that generate high gross value added are also very water demanding.
Around 7-8 % of total agricultural areas are irrigated in Europe (source: Eurostat, online data code: ef_oluaareg; Eurostat, online data code: ef_poirrig), with this value reaching 15 % in southern Europe. Despite the fact that only a small proportion of agricultural land is irrigated, around 40-45 % of total water use in Europe is allocated to crop irrigation annually. Crop irrigation is particularly intensive (80 % of the total water used in southern Europe) between April and August, when crops grow, precipitation decreases and actual evapotranspiration increases.
Southern Europe uses around 90 % of the total volume of water for irrigation in Europe, half of which is used solely in seven river basin districts: Ebro (10 %), Po (9 %), Southern Apennines (9 %), Guadiana (7 %), Tagus and Western (7 %), Jucar (6 %) and Douro (6 %). All of these river basins experience water scarcity conditions throughout the entire year.
Political and socio-economic transitions in eastern Europe, combined with the economic recession in southern Europe (EC, 2013), have resulted in a decline in utilised irrigated areas (by 14 %). In turn, estimations of trends in water use for irrigation suggest a substantial decline (23 %) between 1990 and 2015.
The agricultural sector generated more gross value added (40 %) in 2015 than it did in 1990. However, there are still much rooms for improvement in irrigation efficiency. In many cases, water is abstracted off-stream and conveyed over long distances, via open channels, ditches or pipes, to supply water for irrigation. During this transportation, a portion of the water is lost via either evaporation or leakages in the conveyance systems (resulting in a decrease in irrigation efficiency). No comprehensive data are available to undertake a review of European irrigation efficiency, although some literature suggests that the irrigation efficiency is between 20 and 50 % (Clemente at al., 2013; Baldock et al., 2000; Brouwer at al., 1989).
Crop patterns also determine the amount of water needed for irrigation. Favouring crop types with higher gross value added but that are also more water demanding, such as citrus fruits and energy crops, puts pressure on water resources.
In the coming years, a slight increase in the water requirement for irrigation (EEA, 2014a), associated with a decrease in precipitation in southern Europe (EEA, 2015b), together with the lengthening of the thermal growing season, may be expected.
The use of water in energy generation
Water is abstracted for generating electricity through hydro or thermal power, i.e. for cooling. While hydropower generation involves storing water behind a dam or reservoir in order to use its hydraulic energy to move turbines, the generation of thermal power involves the use of water to cool hot steam used to move turbines.
In general, water for hydropower is abstracted in-stream and regarded as non-consumptive. However, it is not impact free. Hydropower generation leads to changes in natural water cycles in rivers and lakes, deteriorates erosion and sedimentation patterns in river beds and causes substantial changes in riparian ecosystems.
In 2015, hydropower generated 14 % of total electricity production in Europe. Norway, Albania, Iceland, Montenegro and Austria produce more than half of their total electricity from hydropower. Despite the fact that the hydropower production capacity of Europe is, overall, increasing (Eurostat, online data code: nrg_113a), Europe still meets around 60 % of total electricity demand from thermal power (Eurostat, online code: nrg_105a). Every year, roughly 100 000 hm3 of freshwater is abstracted to generate this energy. Cooling installations return water back to the environment at increase temperature (resulting in heat emissions). Heat emissions to water make the way favourable for invasive species and act as barrier to native species moving upstream. In turn, invasive alien species may diminish the provision of water for cooling (Rajagopal et al., 2012).
Sectors that consume large amounts of electricity, such as industry (35-40 %), households and services (both 30 %) (EEA, 2017; Eurostat, online code; nrg_100a), are also major water users. Hence, these sectors put pressure on water resources both directly and indirectly.
In 2015, cooling in energy generation used around 28 % of the total water consumed in Europe, being the second highest consumer of water following agriculture. France and Germany used almost half of it, followed by Italy, the Netherlands, Poland and Spain, all using 6 %.
The energy-related cooling sector is the only sector in Europe in which the use of water is estimated to have increased (by 19 %) between 1990 and 2015. Southern and western Europe increasingly use water for cooling. Shutting down some old nuclear reactor units in eastern Europe (ECA, 2016) lowered water demand for cooling in this part of Europe. Although the use of water for cooling in energy generation has increased, the final consumption of electricity decreased by 2.8 % between 2004 and 2014 because of lower energy production and efficiency gains (EEA, 2017). Therefore, it is not always true that a higher consumption of water for cooling equates to the production of more energy.
Manufacturing and construction, mining and quarrying
The manufacturing industry encompasses various industrial sectors, such as the pulp and paper, iron and steel, textiles, food and beverages, and chemicals sectors, that use water in production processes. Some industries, such as the food industry, also incorporate water into products.
Industrial production increased by 18 % from 1990 to 2015 (2010 = index 100, Eurostat, online data code: str_inpr_a) because of technological improvements combined with high efficiency gains. It is estimated that there has been an absolute decoupling of the gross value added (+38 %) generated by the manufacturing industry (Eurostat online data code: [naida_10_a10]) and water use, with an estimated decline of 35 % between 1990 and 2015. Changing production processes, technological improvements, and recycling and reusing water all lead to gains in efficiency and, in turn, reduce water use. The highest efficiency gains in water use were achieved in southern Europe (-52 %) followed by western Europe (-45 %) and northern Europe (-12 %). In eastern Europe, efficiency is low, with a relative increase in water use (8 %) by the manufacturing industries.
The extraction of minerals, e.g. coal and ores, petroleum and gases, is typical of the mining industry. This industry also undertakes supplementary activities to prepare materials for market, e.g. crushing, grinding, cleaning, drying, sorting, concentrating ores, liquefaction of natural gas and agglomeration of solid fuels.
The mining industry uses water in production processes, e.g. dust depression and rock crushing, as well as in dewatering processes for removing water from mines. Therefore, the mining industry carries out off-stream water abstraction but also water discharge at the same time as the dewatering process, resulting in substantial levels of water-borne emissions and pollutants. Water abstraction for mining usually lowers the groundwater table and deteriorates water quality because of the high levels of emissions released from the dust depression and dewatering processes.
Available data on water abstraction and water use for mining are very limited. This means that there is a high degree of uncertainty in relation to water abstraction for the mining industry. Nevertheless, it is estimated that there was a substantial decrease (44 %) in water abstraction by the mining industry during the 1990-2015 period. Western Europe accounted for more than half of water abstraction for mining, followed by southern Europe (24 %), in 2015.
The water collection, treatment, supply and service sector
Improving access to drinking water and sanitation services is one of the global water policy objectives (United Nations Sustainable Development Goals 6.1 and 6.2). The public water supply industry uses relatively large amounts of water of a certain quality (i.e. drinking water quality) from the environment to provide sufficient water to meet societal needs. Water is supplied by utilities companies to households for domestic needs and to other industries, e.g. business and production services, food and beverage, and accommodation sectors.
Water collection, treatment and supply relate to water supplies for both households and the services sector. Around 64 % of the total public water supply, on average, goes to households, while the remainder is allocated to other connected services. In most European countries, more than 80 % of the total population is connected to the public water supply (the latest data in 2015), except Romania (64 %) and Bosnia and Herzegovina (56 %).
The public water supply accounts for 14 % of total water use in Europe. Hot spots are metropoles, high population density areas and popular tourist destinations. In Europe, solely the Southern Europe accounted around 40 % of total water abstraction for public water supply in 2015.
Improvements in water conveyance systems have resulted in an estimated decrease of water use for households by 18 %, whereas Europe’s population has increased by around 10 % in the last two decades. Substantial water savings have been achieved in western Europe, with the water supply to households declining from 230 litres per capita in 1990 to 134 litres per capita in 2015. However, European metropoles and dry regions are still the most vulnerable to water stress.
On average, 144 litres of water per capita per day is supplied to households in Europe. This water is used for drinking, cooking, personal washing, cleaning the home and clothes, sanitation, waste disposal and gardens. This figure excludes recycled, reused and desalinated water, and water self-supply by other economic sectors. As 50 litres per person per day is adopted as the minimum to meet basic human needs (Brown and Matlock, 2011), the European average seems sufficiently above that threshold to ensure sufficient water provisions for all European citizens.
Economic sectors release water back into the environment after use. That proportion of water is collected and treated by waste water treatment plants to eliminate emission pollution. During the last decade, significant improvements have been made in connecting populations in southern and eastern Europe to waste water treatment facilities. However, around 30 million inhabitants are still not connected to waste water treatment plants in Europe.
Economic production versus water use in Europe
Based on estimations, water abstraction and water use in Europe have decreased since the 1990s. Measures on water pricing, technological improvements in water use appliances and the transition to the free market in eastern Europe may account for this decrease. An absolute decoupling between water abstraction and gross value added generated from all economic sectors at basic price may also explain this decrease (Fig. 7). Water abstraction has decreased by around 9 % in the EU-28, while the gross value added from all economic sectors increased by 52 % between 2000 and 2015, that is, there has been absolute decoupling in the EU economy.
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.
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).
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.
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 EU's Seventh Environment Action Programme (7th EAP) aims to ensure that stress on renewable water resources is prevented or significantly reduced by 2020 (EU, 2013). The EU’s Roadmap to a Resource Efficient Europe (EC, 2011) also includes a milestone for 2020, namely that ‘water abstraction should stay below 20 % of available renewable freshwater resources’. European-scale estimations of water scarcity are likely to shadow large local differences and would thus be misleading. Instead, estimations of the proportional area affected by water scarcity conditions (either seasonally or throughout an entire year) may better capture the actual level of water stress on the continental scale.
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.
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, 2013) 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.
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.
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, 2013), 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 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;
The Danube river basin is accounted for as a single district in Ecrins, so it aggregates a lot of regional and national information.
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.
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.
For references, please go to https://www.eea.europa.eu/data-and-maps/indicators/use-of-freshwater-resources-2/assessment-3 or scan the QR code.
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