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

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

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

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

Estimating irrigation use and effects on maize yield during the 2003 heatwave in France

The decline in maize yield and production during the 2003 heatwave and associated drought in France was only partly minimized by irrigation. National 2003 maize yield loss equaled $\sim$1.5 t ha$^{-1}$ compared to the 2000-2006 average. Spatially distributed maize irrigated area percentages were calculated earlier \citep{wriedt09a} and correlate negatively to the 2003 yield anomaly between 44.5$^{\circ}$ and 48$^{\circ}$ latitude. The percentages are used to weight irrigated and rainfed simulations with the EPIC crop-growth model that runs on a 10 by 10 km grid with relevant land use, terrain, soil and management information. Maize was not irrigated in one simulation while other simulations allowed for daily, weekly and biweekly irrigation with a maximum application of 60 mm day$^{-1}$. The model reasonably reproduces regionally reported yields from 1999-2003. In regions with maize area irrigation percentages $>$20\% yield loss in 2003 was reduced by $\sim$53\% relative to regions with maize irrigation percentages $<$20\%. Similarly, simulated yield loss was compensated by irrigation by $\sim$25\% with biweekly and by $\sim$42\% with weekly irrigation in these regions. Even though yield loss was lower in regions with higher maize irrigation percentages; yield loss was still very considerable. Modelling suggests that regional drought mitigation increased with increasing maize irrigation percentages between 0-40\%. At higher irrigation percentages the compensating effect of irrigation was small. Although the current irrigation infrastructure is sufficient under normal meteorological conditions, areas without irrigation infrastructure experienced high irrigation requirements during the extreme conditions in 2003. Since increasing the irrigation frequency from two weeks to one week had a significant impact on maize yield in 2003, but not in 2002, the most appropriate difference in irrigation rate is provided by the difference between the biweekly rate in 2002 (484 mm year$^{-1}$) and the weekly rate in 2003 (743 mm year$^{-1}$) which equals 259 mm year$^{-1}$. This corresponds to an increase in irrigation water use of $\sim$1761 million m$^{3}$ compared to 2002 ($\sim$0.68 million ha of irrigated maize). Adapting to increased frequency of droughts under further climate change will require robust water allocation policies.JRC.H.1-Water Resource

Estimating Irrigation Water Requirements in Europe

Irrigated agriculture is one of the major water users in southern Europe putting water resources at risk. However, consistent information on irrigation water use in the European Unition are still lacking. We applied the crop growth model EPIC to calculate irrigation requirements in the EU and Switzerland, combining available regional statistics on crop growth and irrigated areas with spatial data sources on soils, land use and climate. The model was applied at a 10x10km grid covering the EU territory. The irrigation requirements reflect the spatial distribution of irrigated areas, climatic conditions and crop mix. A comparison to national data on water abstractions for irrigation generally showed consistent behaviour between calculations and observations though deviations do exist, which were attributed not only to limitations of the model but also to limitations in the assessment of statistical data and to the conceptual differences between irrigation requirements and actual water use. In support of European environmental and agricultural policies, this work provides a large scale overview on irrigation water requirements in Europe applying a uniform approach with a sufficiently high spatial resolution to support identification of hot-spots and regional comparisons. It will also provide a framework for national activities estimating irrigation water use.JRC.H.1-Water Resource

A European irrigation map for spatially distributed agricultural modelling

We present a pan-European irrigation map based on regional European statistics, a European land use map and a global irrigation map. The map provides spatial information on the distribution of irrigated areas per crop type which allows determining irrigated areas at the level of spatial modelling units. The map is a requirement for a European scale assessment of the impacts of irrigated agriculture on water resources based on spatially distributed modelling of crop growth and water balance. The irrigation map was compiled in a two step procedure. First, irrigated areas were distributed to potentially irrigated crops at a regional level (European statistical regions NUTS3), combining Farm Structure Survey (FSS) data on irrigated area, crop-specific irrigated area for crops whenever available, and total crop area. Second, crop-specific irrigated area was distributed within each statistical region based on the crop distribution given in our land use map. A global map of irrigated areas with a 5' resolution was used to further constrain the distribution within each NUTS3 based on the density of irrigated areas. The constrained distribution of irrigated areas as taken from statistics to a high resolution dataset enables us to estimate irrigated areas for various spatial entities, including administrative, natural and artificial units, providing a reasonable input scenario for large-scale distributed modelling applications. The dataset bridges a gap between global datasets and detailed regional data on the distribution of irrigated areas and provides information for various assessments and modelling applications.Irrigation Agriculture Irrigated area Crops Modelling Continental scale Water management Europe FSS GMIA MIRCA