Towards a General Water Balance Assessment of Europe

Large proportions of water supply in European countries rely on groundwater resources, and many aquifers in water scarce regions are overexploited. Water management relies on reasonable information on water availability as well as on water demands by different sectors. Information on water availability and water needs are crucial to identify hot spots of quantitative pressures on water resources. This report focuses on estimating natural water availability across Europe. Simple water balance models were applied for an assessment of available water and potentials and limitations of their application are shown. Special emphasis is given to the role of groundwater in the water cycle and we explore ways to derive groundwater balance terms for large scale assessments. We further develop indicators of water quantity pressure relating water availability to water use and losses at different spatial scales. A short overview on the functioning of groundwater systems is given, highlights properties, processes and problems relevant for groundwater quantity and quality assessment. Some concepts to address groundwater issues at large scale are derived. The methodological part combines a general water balance assessment at large scale with more specific approaches to characterize groundwater systems and to quantify groundwater balance terms at large scale. Two different water balance modelling approaches are applied estimating the amount of water available for direct and subsurface runoff. The modelling approaches are compared to observed values and to each other. The available water is compared to water abstractions developing to indicators for human pressures on water resources. Focusing more specifically on groundwater systems, different methods to calculate baseflow and groundwater recharge are applied and compared and a prototype groundwater recharge map of Europe is presented. The report concludes with a synthesizing discussion of methods and results and an outlook on possible future studies. The individual studies have not yet been integrated into a common framework. Rather, they show various restrictions that require further research on various specific issues relevant for water management at European scale. The approaches laid out in this report and related reports provide a starting point for further development of screening approaches to be integrated in a common water resources assessment framework.JRC.H.5-Rural, water and ecosystem resource

Large Scale Screening of Seawater Intrusion Risk in Europe - Methodological Development and Pilot Application Along the Spanish Mediterranean Coast

Seawater intrusion caused by overabstraction has become an important problem in coastal areas of the Mediterranean. Intrusion processes highly depend on complex local conditions and studies generally focus on specific problems of individual aquifers. Seawater intrusion problems have hardly been addressed at large scale due to the strong impact of local conditions and the problems related to data collection for large geographical areas. To fill this gap and to explore the potential use of readily available data sources, we developed a simple screening methodology for large scale assessment of seawater intrusion risk along the Mediterranean coast of the EU based on a two tiered assessment procedure. Tier 1 is a simple risk assessment based on the balance of groundwater recharge and water abstractions for coastal areas. A positive net groundwater recharge results in transition of the saltwater-freshwater interface to a new equilibrium state. No equilibrium exists with negative net recharge (over-abstraction) and seawater is drawn into the aquifer compensating freshwater losses. Tier 2 provides a quantitative characterization of seawater intrusion for standardized aquifers considering generalized local geological conditions: A simple analytical intrusion model calculates freshwater loss and seawater progression for specified combinations of aquifer properties, aquifer dimensions and boundary fluxes (recharge and abstractions). An unstressed quasi-natural state (recharge only) is compared with a stressed state adding the current level of abstractions. The estimation of groundwater recharge and the spatial disaggregation of national water abstraction data are still tentative and future improvement of the procedures is necessary. A pilot application was carried out for the coast of SE-Spain. As geological data did not support an assessment of individual ¿true¿ coastal aquifers, we defined standardized aquifer domains of different size and applied the seawater intrusion model (Tier 2) to each aquifer domain using local geology and boundary fluxes. Freshwater loss and progression of the saltwater-freshwater interface illustrate the potential severity of potential intrusion processes. The approach supports screening of intrusion risk over large geographical areas based on local relation of abstraction and recharge. The methodology is principally promising, even though input data used for the pilot studies are still based on tentative approaches and need to be replaced by more detailed analysis of statistical information and modelling. Water demand and groundwater recharge as basic input data can be linked to model applications, allowing assessment of future intrusion problems in the context of scenario analysis (for example assessing changes of intrusion risk based on climate change, land use changes and changes in water demands).JRC.H.5-Rural, water and ecosystem resource

A spatially distributed assessment of water allocation in EU27 for Year 2000

Water management relies not only on data on water availability, but also on data on water abstractions and demands. Hydrological modelling studies often neglect the impact of water abstractions and not all models are designed to handle abstractions. Given the various activities for European scale assessments made at the JRC and other institutions, it is desirable to have quantitative and spatially distributed background information on water abstractions, losses and returns to better judge the potential relevance of human abstractions on water quantity and to have reasonable estimates for modelling purposes. The work presented in this report aims at evaluating the potential of readily available data from the OECD/EUROSTAT Joint Questionnaire on Inland Waters and relevant EUROSTAT data to support regionalized water balance assessments including human water abstraction and consumption. This report further document the methodological approaches to generate maps on water abstractions, losses and returns across the EU at 10x10km resolution. Specific tasks documented in this report include: • Modification and extension of available water abstraction data to generate consistent and complete datasets at national level. • Spatial disaggregation of national data to regional and local (10x10km cell) level using proxy data and simulation results. • Estimation of consumptive water losses and returns • Comparison of water abstractions and losses to water availability and mapping of water resources pressure indicators. The report is organized in three parts. Section 2 describes the data used in this assessment and the approaches to compile the specific data for the Atlas of water use and returns. Section 3 is an Atlas documenting and presenting the datasets. Section 4 is a general discussion of the approaches and results.JRC.H.5-Rural, water and ecosystem resource

Long Term Nutrient Loads Entering European Seas

In 2008, DG ENV invited the JRC to conduct a three year study on the impact of EU environmental legislation on nutrient loads to European Seas. The objective of the study was to perform a long term retrospective analysis (20 years) of land based nutrient loads in European Seas to assess the effectiveness of the EU environmental policies and other management plans adopted by countries with rivers discharging in European Seas, and assess future scenarios linked to alternative management plans different policies to control nutrient loading. The focus is both on the nutrient loading to the sea and the inland response to various policies. The first phase of the study focused on setting up the methodology for year 2000. The work concentrated on data collection and model development. The present report focused on the retrospective analysis including trend analysis (1985-2005). The report describes the change in time of the nutrient loads and their origin, entering European Seas.JRC.DDG.H.5-Rural, water and ecosystem resource

Spatialised European Nutrient Balance

This report describes the estimation of the spatialised nutrient inputs from agriculture and nutrient surplus at the soil surface. Statistical agricultural data from the Farm Structure Survey (FSS) were linked to the spatial information of the CORINE Land Cover 2000 map, producing a European map (EU15) of land use including the crop spatial distribution, consistent with the official crops areas reported by FSS. Nitrogen and phosphorus inputs on soils originating from agriculture were estimated for EU15, and then spatialised based on the land use map, providing European maps of nitrogen and phosphorus mineral fertiliser input, manure application and gross balance at 10 km2 resolution. These maps allow the assessment of nutrient pressures originating from agriculture and constitute a reliable data layer for risk analysis and for process-based models, addressing water and soil qualityJRC.H.5-Rural, water and ecosystem resource

Scenario analysis of pollutants loads to European regional seas for the year 2020. Part I: Policy options and alternative measures to mitigate land based emission of nutrients

A spatially explicit statistical approach (GREEN model) applied to continental Europe on a sub-catchment basis, is used to link input from anthropogenic activities and nutrient loads into European Seas (namely nitrogen and phosphorous). Effectiveness of environmental legislation is assessed at the horizon 2020, emphasizing the regional differences between European countries as well as the respective contribution of anthropogenic changes and hydrological fluctuation in nutrient exports. The set of scenarios analyzed includes a business as usual situation, a full implementation of on going policy options, a change in European diet based on a strong reduction of meat intake, and optimized management of agricultural practices. All prospective analyses are implemented for EU-27 and are discussed in terms of capacities to mitigate land based emissions of nutrient, and also according to their impacts on the loads of nutrient exported to European coastal areas.JRC.H.1-Water Resource

Water Requirements for Irrigation in the European Union

Agriculture is an essential driving force in the management of water use. Especially in Southern European countries, irrigation is an essential element of agricultural production and agricultural water use has a substantial share in total water use (exceeding 50%). The presented work contributes to the assessment of impacts of irrigated agriculture on water resources at European scale. We developed a modeling approach to estimate irrigation water requirements and regional irrigation water demands in the EU at high spatial resolution. The modeling approach was applied for a first assessment of irrigation water requirements. A prerequisite of the analysis was the compilation of a European Irrigation Map (EIM), providing information on the distribution of irrigated areas in EU25 for modeling studies. The EIM complements the underlying European land use map (Grizzetti et al. 2007), combining FSS statistics on irrigated area and crop area and information from the Global Map of Irrigated Areas (Siebert et al. 2005). The map was used to derive irrigated areas (as total and per crop) for spatial modeling units. To estimate irrigation water requirements we applied the soil water and crop growth model EPIC that was implemented in a European agricultural modeling system EAGLE and calculates water and nutrient flows at a spatial resolution of 10x10 km raster cells. Different irrigation strategies were defined to analyze the effect of application rates and irrigation intervals on water requirement. The final results were given per raster cell and per crop, based on the most efficient irrigation strategy (maintaining optimum yield with lowest irrigation). We show that allowing higher soil water deficit does not automatically lead to non-tolerable reduction of crop yields and soil moisture. Irrigation requirements (irrigation per unit irrigated area) in Europe range up to 2368 mm/yr in average per cell. Water demands (volume for defined spatial units) are calculated subsequently based on the irrigated area within each cell. Resulting water abstractions were calculated using rules-of-thumb values of irrigation efficiency and conveyance efficiency. A comparison with reported national statistics on water abstraction data showed considerable discrepancies for many countries, indicating not only model uncertainties, but also illustrating shortcomings of national statistics. Such a comparison is a useful tool to check the consistency of both, model assumptions and underlying statistical information. The results provide a spatial overview on irrigation water demands in Europe and allow analysis of agricultural pressures on water resources in Europe at a considerable high spatial resolution. Being based on a single methodology applied to official data sources, the estimation supports inter-comparison of national statistics, which are based on different methodological approaches. This pilot assessment was based on irrigation and land use statistics from the years 2000 and 2003. The methodology was designed for application in an operational context, allowing future updates of the assessment corresponding to statistical data. The approach can therefore principally be applied and extended to track ongoing development or run future scenarios of land use and climate. Future improvements will rely on the development of the underlying statistical information and on the incorporation and improvement of crop specific information.JRC.H.5-Rural, water and ecosystem resource

Modelling nutrient pollution in the Danube River Basin: a comparative study of SWAT, MONERIS and GREEN models

The Water Framework Directive requires the development and implementation of river basin management plans for improving the ecological status of freshwater bodies throughout Europe. The scientific community supports this process by developing decision-support tools for identifying the principal sources of water pollution. Models, however, are imperfect representations of the real world, and are conditioned by structural uncertainty, implicit in the description of biophysical processes, and data uncertainty, as well as in the various restrictions of the environmental data the models were developed. Hence, decision makers must plan management actions on the basis of the best available, however still incomplete, knowledge. The comparison of independent assessments may offer insights that are useful for decision-making, e.g. for identifying knowledge gaps, identifying data uncertainties, consolidating investigation results, and increasing stakeholders’ acceptance. The Danube River is the second largest and most international river of Europe. Its basin covers approximately 803,000 km2 of Central and South-Eastern Europe and is shared by 19 countries. Within the context of fostering scientific collaboration in the Danube region and under the auspices of the International Commission for the Danube River Protection (ICPDR), three independent model (SWAT, MONERIS and GREEN) were compared with the objective of reaching a shared appraisal of nutrient pressures and drivers in the Danube Basin. Annual water discharge (Flow, m3/s) as well as annual loads of total nitrogen (TN, ton/y) and total phosphorus (TP, ton/y) were compared at the outlet of 18 ICPDR regions for the decade 2000-2009. For each region, mean annual values, correlation, standard deviation, and root mean square error of model simulations were analysed. Good water discharge simulations across the basin confirmed that hydrology was correctly represented in all models. The nutrients comparison revealed for some assessment regions the need for a spatially and temporarily intensified monitoring especially for TN. Concerning TP, SWAT and MONERIS had comparable long mean annual TP loads, but differed for amplitude and phases; while GREEN generally overestimated TP loads. Despite differences in model approaches and considered input data, the three assessments were coherent, and all three models may be confidently used for river basin management of the region.JRC.H.1-Water Resource

Identifying efficient Nitrate reduction strategies in the Upper Danube

Nitrogen losses in the form of Nitrate (N-NO3) from point and diffuse sources of pollution are recognized to be the leading cause of water body impairment throughout Europe. Implementation of conservation programs is perceived as being crucial for restoring and protecting the good ecological status of freshwater bodies. The success of conservation programs depends on the efficient identification of management solutions with respect to the envisaged environmental and economic objectives. This is a complex task, especially considering that costs and effectiveness of conservation strategies depend on their locations. We applied a multi-objective, spatially explicit analysis tool, the R-SWAT-DM framework, to search for efficient, spatially-targeted solution of Nitrate abatement in the Upper Danube Basin. The Soil Water Assessment Tool (SWAT) model served as the nonpoint source pollution estimator for current conditions as well as for scenarios with modified agricultural practices and waste water treatment upgrading. A spatially explicit optimization analysis that considered point and diffuse sources of Nitrate was performed to search for strategies that could achieve largest pollution abatement at minimum cost. The set of optimal spatial conservation strategies identified in the Basin indicated that it could be possible to reduce Nitrate loads by more than 50% while simultaneously provide a higher income

A decision support tool (R-SWAT-DS) for integrated watershed management

Best management practices (BMPs) can be used effectively to reduce nutrient and sediment loads generated from point sources or non-point sources to receiving water bodies. Methodologies for optimal, cost effective BMP selection and placement are needed to assist watershed management planners and stakeholders. We developed a modeling-optimization framework that can be used to find cost-effective solutions of BMP placement to attain nutrient load reduction targets. The framework integrates the Soil and Water Assessment Tool (SWAT) watershed model, spatial representation of BMPs, an economic component, and multi-objective optimization routines in the R environment. The framework can be used to launch individual or iterative BMPs simulations, or search for optimal strategies. Advanced plotting, mapping and statistical analysis functionalities that facilitate the interpretation and assessment of the results are included