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The supply of water, food, and energy in our global economy is highly interlinked. Virtual blue water embedded into internationally traded food crops has therefore been extensively researched in recent years. This study focuses on the often neglected energy needed to supply this blue irrigation water. It provides a globally applicable and spatially explicit approach to the watershed level for water source specific quantification of energy consumption and related greenhouse gas (GHG) emissions of irrigation water supply. The approach is applied to Israel's total domestic and imported food crop supply of 105 crops by additionally including import‐related transportation energy and emissions. Total energy use and related emissions of domestic crop production were much lower (551 GWh/422 kt CO2‐equivalents [CO2e]) than those embedded into crop imports (1639 GWh/649 kt CO2e). Domestic energy and emissions were mainly attributable to the irrigation water supply with artificial water sources (treated domestic wastewater and desalinated water, 84%). Transport accounted for 79% and 66% of virtually imported energy and emissions, respectively. Despite transport, specific GHG emissions (CO2e per ton of crop) were significantly lower for several crops (e.g., olives, almonds, chickpeas) compared to domestic production. This could be attributed to the high share of energy‐intensive artificial water supply in combination with higher irrigation water demands in Israel. In the course of an increasing demand for artificial water supply in arid and semi‐arid regions, our findings point to the importance of including "energy for water" into comparative environmental assessment of crop supply to support decision‐making related to the water–energy–food nexus. [ABSTRACT FROM AUTHOR]

Aiming to enhance the analysis of water consumption and resulting consequences along the supply chain of products, the water accounting and vulnerability evaluation (WAVE) model is introduced. On the accounting level, atmospheric evaporation recycling within drainage basins is considered for the first time, which can reduce water consumption volumes by up to 32%. Rather than predicting impacts, WAVE analyzes the vulnerability of basins to freshwater depletion. Based on local blue water scarcity, the water depletion index (WDI) denotes the risk that water consumption can lead to depletion of freshwater resources. Water scarcity is determined by relating annual water consumption to availability in more than 11?000 basins. Additionally, WDI accounts for the presence of lakes and aquifers which have been neglected in water scarcity assessments so far. By setting WDI to the highest value in (semi)arid basins, absolute freshwater shortage is taken into account in addition to relative scarcity. This avoids mathematical artifacts of previous indicators which turn zero in deserts if consumption is zero. As illustrated in a case study of biofuels, WAVE can help to interpret volumetric water footprint figures and, thus, promotes a sustainable use of global freshwater resources. [ABSTRACT FROM AUTHOR]

This work identifies shortcomings in water footprinting and discusses whether the water footprint should be a volumetric or impact-oriented index. A key challenge is the current definition of water consumption according to which evaporated water is regarded as lost for the originating watershed per se. Continental evaporation recycling rates of up to 100% within short time and length scales show that this definition is not generally valid. Also, the inclusion of land use effects on the hydrological balance is questionable, as land transformation often leads to higher water availability due to locally increased runoff. Unless potentially negative consequences, such as flooding or waterlogging, and adverse effects on the global water cycle are considered, water credits from land transformation seem unjustified. Most impact assessment methods use ratios of annual withdrawal or consumption to renewability rates to denote local water scarcity. As these ratios are influenced by two metrics-withdrawal and availability-arid regions can be regarded as uncritical if only small fractions of the limited renewable supplies are used. Besides neglecting sensitivities to additional water uses, such indicators consider neither ground nor surface water stocks, which can buffer water shortages temporally. Authors favoring volumetric indicators claim that global freshwater appropriation is more important than local impacts, easier to determine, and less error prone than putting complex ecological interaction into mathematical models. As shown in an example, volumetric water footprints can be misleading without additional interpretation because numerically smaller footprints can cause higher impacts. [ABSTRACT FROM AUTHOR]

Due to global increase of freshwater scarcity, knowledge about water consumption in product life cycles is important This study analyzes water consumption and the resulting impacts of Volkswagen's car models Polo, Golf and Passat and represents the first application of impact-oriented water footprint methods on complex industrial products. Freshwater consumption throughout the cars' life cycles is allocated to material groups and assigned to countries according to import mix shares or location of production sites. Based on these regionalized water inventories, consequences for human health, ecosystems, and resources are determined by using recently developed impact assessment methods. Water consumption along the life cycles of the three cars ranges from 52 to 83 m3/car, of which more than 95% is consumed in the production phase, mainly resulting from producing iron, steel, precious metals, and polymers. Results show that water consumption takes place in 43 countries worldwide and that only 10% is consumed directly at Volkswagen's production sites. Although impacts on health tend to be dominated by water consumption in South Africa and Mozambique, resulting from the production of precious metals and aluminum, consequences for ecosystems and resources are mainly caused by water consumption of material production in Europe. [ABSTRACT FROM AUTHOR]

• We present the first full review of research pertaining a water planetary boundary. • Initial shortcomings of the water planetary boundary have partly been resolved. • Input-output analysis may facilitate investigation into the exceedance of boundaries. • Spatiotemporal mismatches amid input-output and hydrological data pose a challenge. The water planetary boundary has been proposed to determine limits for a sustainable anthropogenic appropriation of freshwater. Aim of the present research was to summarise the water planetary boundary's development status and applications including its integration into Life Cycle Assessment and Environmentally-Extended Input-Output-Analysis. A systematic literature review was conducted for studies featuring the keywords "planetary boundary" and "water consumption". All pertinent studies were categorised as either revision, commentary, stand-alone application, the application within Life Cycle Assessment or application within Environmentally-Extended Input-Output Analysis and subsequently summarised and discussed. Overall, 35 studies from the period of 2009 until mid-2020 are subject of this review. Recent advancements such as spatially differentiated thresholds and refined sub-boundaries have addressed initial shortcomings of the concept of a water planetary boundary. Stand-alone applications of the water planetary boundary have either established local thresholds or allocated fair shares of afore-defined global thresholds. Several authors integrated the concept of a water planetary boundary into LCA e.g. via characterisation factors, weighting or normalisation, often under consideration of sharing principles. An application of the water planetary boundary into Environmentally-Extended Input-Output Analysis is less represented although some authors have demonstrated its powerfulness in investigating causes for the exceedance of local thresholds. For some of the reviewed studies, a link to the water planetary boundary remains rather vague as these studies merely investigate water availability in comparison to consumption. Although it should be applied with caution, the concept of a planetary boundary for freshwater use can contribute to understanding limits to sustainable freshwater consumption. Many studies established water use thresholds but refrained from analysing causative drivers in detail. Challenges for exploring this further include overcoming spatial and temporal mismatches of environmentally-extended economic accounts and hydrogeological data. [ABSTRACT FROM AUTHOR]

Due to the increasing relevance of analyzing water consumption along product life cycles, the method of Water Footprinting gained rising attention in the last years. In this context the water accounting and vulnerability evaluation model (WAVE+) was developed at the TU Berlin. Based on a consumption-to-availability ratio derived from the hydrological model WaterGap3, WAVE+ currently analyzes the vulnerability of basins to freshwater depletion in more than 8.000 basins. On the accounting level the atmospheric evaporation recycling within drainage basins is considered which can reduce the water consumption volumes within specific basins significantly. However, the model does not consider evaporation recycling patterns across basin boundaries until now.This research focuses on the enhancement of the method by including the latter point. In addition to the consideration of the basin internal evaporation recycling (BIER) the basin external evaporation recycling (BEER) is included for the first time. The main outcome are monthly and basin-specific recycling patterns which are able to show in which drainage basins evaporated water will finally re-precipitate. The results were gained from the atmospheric moisture tracking model WAM-2layers which was fed with climatic input data from the ERA-Interim reanalysis on a 1.5° latitude and 1.5° longitude grid for the period of 2001-2010. With regard to evaporation data, the Era-Interim data were replaced by data of the hydrological model WaterGap3 to ensure consistency with the WAVE+ model. The import and export of water flows were aggregated according to the basin delineation of the WAVE+ method.First results for the region around Berlin show that most of the evaporated water re-precipitates over land, mainly in basins located in Eastern Germany, Poland, Czech Republic, Slovakia and the Ukraine. With regards to the region of Central Borneo most of the re-precipitation takes place on the island itself as well as over the surrounding sea and East Indonesia. In addition to presenting basin-specific recycling patterns, the research discusses methodological aspects on how those results could potentially be used within the scope of Water Footprinting. In order to enable further application purposes, the un-aggregated raw data of the fate analysis of evaporated water will be provided on a 1.5° latitude and 1.5° longitude grid and be made publicly available. [ABSTRACT FROM AUTHOR]

• Water scarcity is determined for 17 irrigation subdivisions in Pakistan. • Water deprivation index varies from 0.08 to 1.0 m3 deprived /m3 consumed. • Southern areas are up to ten times more water-scare than the northern ones. • The Water Scarcity Footprint of cotton amounts to 1476–2483 m3 deprived per ton. The Water Scarcity Footprint (WSF) serves as a method to estimate the local impacts associated with water consumption in a certain region by considering the volume of water consumed and local water scarcity. Despite the broad application of the WSF on a country and river basin level, the need for further regionalization was recently emphasized by several authors. In this study, water scarcity factors are calculated on high spatio-temporal resolution for 17 irrigation subdivisions located in Punjab, Pakistan on a monthly level based on the WAVE + method using data provided by the hydrological model SWAT and hydraulic model Feflow. The calculated "water deprivation indices" (WDIs) are applied to quantify the WSF of cotton and wheat produced in the study area and compared to the WSFs obtained by using existing WDIs with lower spatial and temporal resolution. The calculated WDIs show a high variability in water scarcity throughout the year from 0.1 to 1.0 m3 deprived /m3 consumed. The production weighted average WSF of cotton calculated with the regionalized WDIs amounts to 2333 m3 deprived per ton, whilst the cotton produced in the south of the study area has a twice as high WSF as the cotton from the northern irrigation subdivisions. The result calculated based on the high resolution WDIs is more than 60% higher than the WSF calculated with the WDIs on the basin level. The regionalized WSF of wheat amounts to 1821 m3 deprived per ton, which aligns with the WSF calculated with the basin specific WDIs. The study underlines the need for water scarcity factors on high spatial (e.g. irrigation subdivision) and temporal (monthly) resolution to provide robust WSF results. [ABSTRACT FROM AUTHOR]