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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]

Abstract Evaluating the impacts on biodiversity by means of the life cycle assessment (LCA) is a task researchers are currently facing. One impact assessment method that aims to do so is the recently developed biodiversity impact assessment BIA+. The aim of the present paper is to test this method and to show its applicability and feasibility. Additionally opportunities and challenges of this method shall be revealed. For this purpose, a case study for assessing the impacts of biodiesel production on freshwater biodiversity is introduced. Two substances, namely phosphorus and 1,4-dichlorobenzene (DCB), which are used for the biodiesel production for fertilization and the usage of pesticides, are being considered. The inventory data needed for the case study is gathered through the grey water footprint of the crop production that forms the basis of the European biodiesel consumption. Further, the BIA+ method is applied in order to assess the impacts of the biodiesel consumption in Europe for the year 2010 on freshwater biodiversity. The results reveal that even though assumptions have to be made and the results are highly uncertain, this method helps to identify hotspots within production processes. By including the BIA+ as an impact assessment method into LCA, impacts of products can be assessed with regard to biodiversity including genetic, species and ecosystem diversity. The main impact hotspot occurs in France with a potential loss of the biodiversity of 0.5 points. The lowest loss of the biodiversity occurs in Brazil (loss of 8.05*10–06 points). The results are mainly influenced by the impact of the toxic substance 1,4-DCB. By means of the case study, it is shown that the BIA+ method is applicable. [ABSTRACT FROM AUTHOR]

Water footprinting has emerged as an important approach to assess water use related effects from consumption of goods and services. Assessment methods are proposed by two different communities, the Water Footprint Network (WFN) and the Life Cycle Assessment (LCA) community. The proposed methods are broadly similar and encompass both the computation of water use and its impacts, but differ in communication of a water footprint result. In this paper, we explain the role and goal of LCA and ISO-compatible water footprinting and resolve the six issues raised by Hoekstra (2016) in “A critique on the water-scarcity weighted water footprint in LCA”. By clarifying the concerns, we identify both the overlapping goals in the WFN and LCA water footprint assessments and discrepancies between them. The main differing perspective between the WFN and LCA-based approach seems to relate to the fact that LCA aims to account for environmental impacts, while the WFN aims to account for water productivity of global fresh water as a limited resource. We conclude that there is potential to use synergies in research for the two approaches and highlight the need for proper declaration of the methods applied. [ABSTRACT FROM AUTHOR]