Räumliche Auflösung in der Wasserfußabdruck-Methode: von globaler zu lokaler Ebene

Freshwater withdrawals have been growing continuously since the 1980s and are predicted to further increase by up to 30% until 2050. In many parts of the world this trend leads to raising water scarcity levels and pollution, which cause competition for water between different users, spread of contaminants in the environment and resulting impacts on human health. The Water Footprint (WF) method is applied for the quantification of environmental impacts associated with water use along the life cycle of products and organizations. The method considers regional variation in water scarcity and vulnerability of population to water related impacts by means of characterization factors (CFs) regionalized at a river basin or country scale, which are used in the impact assessment stage. However, it has not been investigated yet if the spatial resolution at a level of river basins and countries is sufficient for an impact assessment at a local scale. This thesis aims at evaluating the potential for the application of site-specific (i.e. local) spatial resolution in WF considering water consumption, water pollution and impacts on human health. To meet this goal, three research questions are formulated and answered in three peer-reviewed publications. The first research question deals with the approaches for addressing water quality in WF. To answer this question, seven existing WF methods for considering water pollution are reviewed and classified. The classification of the methods is based on the type of modelled impact, i.e. intake of contaminants (water degradation footprint, WDF) or water deprivation (water availability footprint, WAF) and adopted impact assessment approach, namely environmental mechanism, Distance-to-Target (DtT) and functionality. Moreover, recommendations for the methods application are provided based on the type of impact caused by water pollution (WDF in case of intake of contaminants and WAF in case of water deprivation) and availability of inventory data (environmental mechanism and functionality approaches require a comprehensive inventory, while for the application of the DtT approach the data on one pollutant is sufficient). Methodological differences including number of considered pollutants, provided thresholds, possibility of region-specific impact assessment etc., and partly controversial results provided by the methods are emphasized by means of a case study for textile production. The second research question is dedicated to the effect of spatial resolution on water scarcity footprint (WSF). To answer this question, local water scarcity CFs are calculated at a level of 17 irrigation sub-divisions in Pakistan following the procedure of the WAVE+ model. The results demonstrate that during August and September, water scarcity levels significantly vary between the irrigation subdivisions, from low scarcity (0.01 to 0.2 m³deprived/m³consumed) in the northern parts of the study area up to the highest scarcity (1.0 m³deprived/m³consumed) in the south. It is shown that these differences are not reflected when applying CFs with a lower spatial resolution, i.e. at a river basin and country scale. Furthermore, the comparison to existing WF models shows high discrepancies between locally modelled and existing water scarcity CFs during some months. For example, in July and August, local CFs show the highest water scarcity level (1.0 and 0.9 m³deprived/m³consumed, respectively) in contrast to the CFs on a basin scale which reach only 0.05 m³deprived/m³consumed (very low water scarcity). These differences can be explained by different levels of spatial detail and underlying hydrological models used for the quantification of CFs. Conducted case study for cotton and wheat cultivation demonstrates that neglecting local differences in water scarcity can result in a significant under- or overestimation of the WSF, which reached 40% in case of cotton grown in the study area. Finally, local cause-effect chains (CECs) for human health damage related to water use are developed for an exemplary region in Pakistan and analysed with regard to their consistency with the CECs provided by existing impact assessment models. Seven local CECs for health damage associated with agricultural and domestic water deprivation as well as water pollution are identified, two of which are currently not covered by any existing WF model. Both new CECs are related to agricultural water deprivation and include income loss that leads to malnutrition and application of wastewater for irrigation to mitigate water shortages, which causes an exposure to contaminants contained in applied effluents. High relevance of the availability of water supply systems is demonstrated for the CECs for domestic water deprivation and pollution of drinking water, which emphasizes the importance of considering socio-economic factors for the human health impact assessment. Furthermore, it is demonstrated that impacts related to pathogen pollution are relevant for the CECs describing wastewater usage in agriculture, therefore, the possibility of their inclusion in a WF model needs to be investigated in future research. This thesis demonstrates the potential of applying site-specific WF impact assessment and reveals its strengths and limitations by carrying out a “reality check” at a local scale. The results of this thesis contribute to the research progress and provide basis for future scientific work on regionalization. Conducting further studies at a local scale may significantly enhance water footprinting by validating existing models and demonstrating their methodological and practical challenges.Frischwasserentnahmen steigen kontinuierlich seit den 1980er Jahren, eine weitere Zunahme des Wasserbedarfs von bis zu 30% wird bis zum Jahr 2050 prognostiziert. Dieser Trend führt zu steigender Wasserknappheit und Verschmutzung von Gewässern in vielen Regionen der Welt, was wiederum zu konkurrierenden Wassernutzungen, Ausbreitung von den Schadstoffen in der Umwelt und den daraus resultierenden Auswirkungen auf menschliche Gesundheit führt. Die Wasserfußabdruck-Methode (WF-Methode) dient zur Quantifizierung der Umweltauswirkungen im Zusammenhang mit der Wassernutzung im Produktlebenszyklus. Mithilfe regionalisierter Charakterisierungsfaktoren (CF), welche für die Wirkungsabschätzung dienen, ermöglicht die WF-Methode, regionale Unterschiede in der Wasserknappheit und der Vulnerabilität lokaler Bevölkerung gegenüber wasserbezogener Auswirkungen zu berücksichtigen. Dennoch ist es unklar, ob die räumliche Auflösung auf Wassereinzugsgebiet- und Länderebene, die in bestehenden WF-Modellen für die Wirkungsabschätzung angewandt wird, auf lokaler Ebene ausreichend ist. Ziel dieser Dissertation ist es, das Potenzial für die Anwendung regional-spezifischer (lokaler) räumlicher Auflösung in der WF-Methode einschließlich der Aspekte Wasserverbrauch, Wasserverschmutzung und menschliche Gesundheit zu untersuchen. Zur Erreichung dieses Ziels werden drei Forschungsfragen formuliert, welche in drei Publikationen beantwortet werden. Die erste Forschungsfrage fokussiert den Aspekt Wasserqualität. Für die Beantwortung dieser Frage wir eine Übersicht von sieben bestehenden Methoden zur Berücksichtigung der Wasserqualität in WF ausgearbeitet, welche anschließend klassifiziert werden. Die Klassifikation der Methoden basiert zum einen auf der Art der modellierten Auswirkungen, bei denen es zwischen Aufnahme der Schadstoffe (eng. Water Degradation Footprint, WDF) und Wasserdeprivation anderer Nutzer (eng. Water Availability Footprint, WAF) unterschieden wird, zum anderen auf dem Ansatz für die Wirkungsabschätzung, darunter Umweltmechanismus, Zielabstandsindikator (eng. Distance-to-Target, DtT) und Funktionalität. Anschließend werden die Empfehlungen für die Anwendung der Methoden ausgearbeitet, welche auf zwei folgenden Aspekten basieren: der Art der Auswirkungen (WDF im Fall der Aufnahme der Schadstoffe und WAF im Fall der Wasserdeprivation) und der Verfügbarkeit der Inventardaten (Wirkungsabschätzung nach dem Umweltmechanismus-Ansatz und der Funktionalität erfordern ein umfassendes Inventar, während für die Anwendung des DtT-Ansatzes die Daten nur für einen Schadstoff ausreichen). Methodische Unterschiede, darunter Anzahl berücksichtigter Schadstoffe, vorgegebene Grenzwerte, die Möglichkeit einer regional-spezifischer Wirkungsabschätzung usw. sowie teilweise kontroverse Ergebnisse einzelner Methoden sind mithilfe einer Fallstudie für die Textilproduktion dargestellt. Die zweite Forschungsfrage richtet sich an den Einfluss regional-spezifischer Auflösung auf den Wasserknappheitsfußabdruck (eng. Water Scarcity Footprint, WSF). Um diese Frage zu beantworten, werden lokale Wasserknappheits-CF basierend auf dem WAVE+-Modell auf Ebene von 17 Bewässerungseinheiten in Pakistan berechnet. Die Ergebnisse zeigen, dass während der Monate Juli und August die Höhe der Wasserknappheit zwischen einzelnen Bewässerungseinheiten stark variiert, von niedriger Knappheit (0.01 bis 0.2 m³deprived/m³consumed) in den nördlichen Regionen des Untersuchungsgebiets bis höchster Knappheit (1.0 m³deprived/m³consumed) im Süden. Es ist dargestellt, dass bestehende WF-Modelle mit einer niedrigeren räumlichen Auflösung, z.B. auf Ebene von Einzugsgebieten oder Ländern, diese Unterschiede nicht wiederspiegeln können. Darüber hinaus werden in einigen Monaten große Unterschiede zwischen lokal modellierten und bestehenden Wasserknappheits-CF identifiziert. So zeigen lokale CFs in den Monaten Juli und August die höchste Wasserknappheit für das Untersuchungsgebiet (1.0 m³deprived/m³consumed), während die CFs auf Wassereinzugsgebiet-Ebene eine sehr niedrige Knappheit aufweisen (0.05 m³deprived/m³consumed). Diese Differenzen können auf den unterschiedlichen Grad der räumlichen Auflösung und zugrundeliegende hydrologische Modelle zurückgeführt werden. Die Fallstudie für den Anbau von Baumwolle und Weizen zeigt, dass die Vernachlässigung lokaler Unterschiede in Wasserknappheit zu einer signifikanten Unter- oder Überschätzung des WSFs führen kann, die im Fall der im Untersuchungsregion angebauten Baumwolle 40% erreicht. Schließlich werden für eine exemplarische Region in Pakistan lokale Ursache-Wirkungsketten entwickelt, die die Schäden für menschliche Gesundheit im Zusammenhang mit Wassernutzung abbilden. Die Ergebnisse werden mit den Wirkungsketten verglichen, welche in den bestehenden Wirkungsabschätzungs-Methoden modelliert werden. Sieben Wirkungsketten werden für die Schäden aufgrund des Wasserentzugs für häuslichen Gebrauch und landwirtschaftliche Bewässerung sowie aufgrund der Wasserverschmutzung entwickelt, wobei zwei von diesen Wirkungsketten in keiner der bestehenden WF-Methoden berücksichtigt sind. Die beiden neuen Wirkungsketten beziehen sich auf den Wassermangel für landwirtschaftliche Nutzung und beschreiben zum einen den Verlust des Einkommens und anschließende Unterernährung, zum anderen die Nutzung des Abwassers für die Bewässerung der Felder, was zu der Aufnahme der Schadstoffe führen kann. Es konnte eine hohe Relevanz der Wasserversorgungssysteme für die häusliche Wassernutzung und auch die Verschmutzung des Trinkwassers aufgezeigt werden, was die Wichtigkeit der Berücksichtigung sozioökonomischer Aspekte in der Wirkungsabschätzung für menschliche Gesundheit unterstreicht. Darüber hinaus werden potenzielle Schäden aufgrund der in dem landwirtschaftlich genutzten Abwasser enthaltenen Krankheitserreger als relevant identifiziert, weswegen die Möglichkeiten für deren Berücksichtigung in WF zukünftig untersucht werden sollten. Diese Dissertation zeigt das Potenzial der Anwendung regional-spezifischer Wirkungsabschätzung in WF auf und offenbart deren Stärken und Einschränkungen unter realen Bedingungen auf lokaler Ebene. Die Ergebnisse dieser Arbeit tragen zu dem wissenschaftlichen Fortschritt bei und dienen als Basis für zukünftige wissenschaftliche Arbeiten im Bereich Regionalisierung. Weitere Studien auf lokaler Ebene können einen großen Beitrag für die Weiterentwicklung der WF-Methode leisten, indem bestehende WF-Modelle validiert und deren methodische und praktische Herausforderungen aufgezeigt werden

Addressing water quality in water footprinting: current status, methods and limitations

Purpose: In contrast to water consumption, water pollution has gained less attention in water footprinting so far. Unlike water scarcity impact assessment, on which a consensus has recently been achieved, there is no agreement on how to address water quality deterioration in water footprinting. This paper provides an overview of existing water footprint methods to calculate impacts associated with water pollution and discusses their strengths and limitations using an illustrative example. Methods: The methods are described and applied to a case study for the wastewater generated in textile processing. The results for two scenarios with different water quality parameters are evaluated against each other and the water scarcity footprint (WSF). Finally, methodological aspects, strengths and limitations of each method are analysed and discussed and recommendations for the methods application are provided. Results and discussion: Two general impact assessment approaches exist to address water quality in water footprinting: the Water Degradation Footprint (WDF) calculates the impacts associated with the propagation of released pollutants in the environment and their uptake by the population and ecosystem, while the Water Availability Footprint (WAF) quantifies the impacts related to the water deprivation, when polluted water cannot be used. Overall, seven methods to consider water quality in water footprinting were identified, which rely upon one or a combination of WDF, WAF and WSF. Methodological scopes significantly vary regarding the inventory requirements and provided results (a single-score or several impact categories). The case study demonstrated that the methods provide conflicting results concerning which scenario is less harmful with regard to the water pollution. Conclusions: This paper provides a review of the water pollution assessment methods in water footprinting and analyses their modelling choices and resulting effects on the WF. With regard to the identified inconsistencies, we reveal the urgent need for a guidance for the methods application to provide robust results and allow a consistent evaluation of the water quality in water footprinting.TU Berlin, Open-Access-Mittel – 2020BMBF, 02WGR1422B, GROW - Verbundprojekt InoCottonGROW: Innovative Impulse zur Verringerung des Wasser-Fußabdrucks der globalen Baumwoll-Textilindustrie in Richtung UN-Nachhaltigkeitsziele, Teilprojekt

Organizational water footprint: a methodological guidance

Purpose This paper proposes a practical methodological approach to assess the water footprint at the organizational level, in line with the current development of life-cycle based approaches toward the organizational scale on the one hand and footprint metrics on the other hand. This methodological development allows for organizational water footprint applications intended to inform management decisions and to alleviate water-related environmental impacts throughout the supply chain. Methods ISO 14046, dedicated to water footprint with a major focus on products, and ISO/TS 14072 for organizational LCA (O-LCA) are compared. A set of indications to carry out an organizational water footprint is identified based on: the requirements common to water footprint and organizational LCA; complementary methodological elements specified in only one of the standards; solutions to issues identified as conflicting. Additional application guidance on data collection prioritization for organizational water scarcity footprint studies is delivered based on the review of existing organizational case studies and comparative product or commodity studies. Results and discussion O-LCA and water footprint provide complementary requirements for the scoping phase and the inventory and impact assessment phase respectively, according to the different methodological foci. We identify conflicting or contradictory requirements related to (i) comparisons, (ii) system boundary definition, and (iii) approaches to avoid allocation. We recommend (i) avoiding comparisons in organizational water footprint studies, (ii) defining two-dimensional system boundaries (“life-cycle dimension” and “organizational dimension”), and (iii) avoiding system expansion. Additionally, when carrying out a water scarcity footprint for organizations, we suggest prioritizing data collection for direct activities, freshwater extraction and discharge, purchased energy, metals, agricultural products and biofuels, and, if water or energy consuming, the use phase. Conclusions The standards comparison allowed compiling a set of requirements for organizational water footprints. Combined with the targeted guidance to facilitate data collection for water scarcity footprint studies, this work can facilitate assessing the water footprint of organizations throughout their supply chains.BMBF, 02WGR1429A, GROW - Verbundprojekt WELLE: Wasserfußabdruck für Unternehmen - Lokale Maßnahmen in Globalen Wertschöpfungsketten, Teilprojekt

Life Cycle Based Comparison of Textile Ecolabels

Environmental impacts of textile production increased over the last decades. This also led to an increasing demand for sustainable textiles and ecolabels, which intend to provide information on environmental aspects of textiles for the consumer. The goal of the paper is to assess selected labels with regard to their strengths and weaknesses, as well as their coverage of relevant environmental aspects over the life cycle of textiles. We applied a characterization scheme to analyse seven selected labels (Blue Angel Textiles, bluesign®, Cotton made in Africa (CMiA), Cradle to Cradle CertifiedTM, Global Organic Textile Standard (GOTS), Global Recycled Standard (GRS), VAUDE Green Shape), and compared their focus to the environmental hotpots identified in the product environmental footprint case study of t-shirts. Most labels focus on the environmental aspects toxicity, water use, and air emissions predominantly in the upstream life cycle phases of textiles (mainly garment production), whereas some relevant impacts and life cycle phases like water in textile use phase remain neglected. We found significant differences between the ecolabels, and none of them cover all relevant aspects and impacts over the life cycle. Consumers need to be aware of these limitations when making purchase decisions

Life Cycle Based Comparison of Textile Ecolabels

Environmental impacts of textile production increased over the last decades. This also led to an increasing demand for sustainable textiles and ecolabels, which intend to provide information on environmental aspects of textiles for the consumer. The goal of the paper is to assess selected labels with regard to their strengths and weaknesses, as well as their coverage of relevant environmental aspects over the life cycle of textiles. We applied a characterization scheme to analyse seven selected labels (Blue Angel Textiles, bluesign®, Cotton made in Africa (CMiA), Cradle to Cradle CertifiedTM, Global Organic Textile Standard (GOTS), Global Recycled Standard (GRS), VAUDE Green Shape), and compared their focus to the environmental hotpots identified in the product environmental footprint case study of t-shirts. Most labels focus on the environmental aspects toxicity, water use, and air emissions predominantly in the upstream life cycle phases of textiles (mainly garment production), whereas some relevant impacts and life cycle phases like water in textile use phase remain neglected. We found significant differences between the ecolabels, and none of them cover all relevant aspects and impacts over the life cycle. Consumers need to be aware of these limitations when making purchase decisions.DFG, 414044773, Open Access Publizieren 2021 - 2022 / Technische Universität Berli

Assessing local impacts of water use on human health: evaluation of water footprint models in the Province Punjab, Pakistan

Purpose The water footprint (WF) method is widely applied to quantify water use along the life cycle of products and organizations and to evaluate the resulting impacts on human health. This study analyzes the cause-effect chains for the human health damage related to the water use on a local scale in the Province Punjab of Pakistan, evaluates their consistency with existing WF models, and provides recommendations for future model development. Method Locally occurring cause-effect chains are analyzed based on site observations in Punjab and a literature review. Then, existing WF models are compared to the findings in the study area including their comprehensiveness (covered cause-effect chains), relevance (contribution of the modeled cause-effect chain to the total health damage), and representativeness (correspondence with the local cause-effect chain). Finally, recommendations for the development of new characterization models describing the local cause-effect chains are provided. Results and discussion The cause-effect chains for the agricultural water deprivation include malnutrition due to reduced food availability and income loss as well as diseases resulting from the use of wastewater for irrigation, out of which only the first one is addressed by existing WF models. The cause-effect chain for the infectious diseases due to domestic water deprivation is associated primarily with the absence of water supply systems, while the linkage to the water consumption of a product system was not identified. The cause-effect chains related to the water pollution include the exposure via agricultural products, fish, and drinking water, all of which are reflected in existing impact assessment models. Including the groundwater compartment may increase the relevance of the model for the study area. Conclusions Most cause-effect chains identified on the local scale are consistent with existing WF models. Modeling currently missing cause-effect chains for the impacts related to the income loss and wastewater usage for irrigation can enhance the assessment of the human health damage in water footprinting.TU Berlin, Open-Access-Mittel – 2021BMBF, 02WGR1422B, GROW - Verbundprojekt InoCottonGROW: Innovative Impulse zur Verringerung des Wasser-Fußabdrucks der globalen Baumwoll-Textilindustrie in Richtung UN-Nachhaltigkeitsziele, Teilprojekt

The Water Footprint of European Agricultural Imports: Hotspots in the Context of Water Scarcity

This study investigates the Water Footprint (WF) resulting from the agricultural imports of the European Union (EU-28). Import trade statistics were compiled and linked with crop- and country-specific water consumption data and water scarcity factors. Within the study, the virtual water imports of 104 agricultural commodities for the baseline year 2015 were assessed and product and country hotspots were evaluated. It was shown that (a) Europe imported 100 million tons of agricultural goods and 11 km3 of associated virtual irrigation water; (b) the highest impacts of water consumption do not necessarily result from high import amounts, but from water-intensive goods produced in water scarce countries; (c) the largest external EU-28 water footprint occurred due to the product categories cotton, nuts and rice; and (d) the highest share of the EU external water footprint took place in the United States (US), Pakistan, Turkey, Egypt and India

Advancing the water footprint into an instrument to support achieving the SDGs – Recommendations from the “Water as a Global Resources” Research Initiative (GRoW)

The water footprint has developed into a widely-used concept to examine water use and resulting local impacts caused during agricultural and industrial production. Building on recent advancements in the water footprint concept, it can be an effective steering instrument to support, inter alia, achieving sustainable development goals (SDGs) - SDG 6 in particular. Within the research program “Water as a Global Resource” (GRoW), an initiative of the Federal Ministry for Education and Research, a number of research projects currently apply and enhance the water footprint concept in order to identify areas where water is being used inefficiently and implement practical optimization measures (see imprint for more information). With this paper, we aim to raise awareness on the potential of the water footprint concept to inform decision-making in the public and private sectors towards improved water management and achieving the SDGs.TU Berlin, Open-Access-Mittel – 202