A contribution to harmonize water footprint assessments
Introduction
The efficient, equitable and sustainable management of our planet’s water resources is one of the main challenges humanity is currently facing. For example, 1.2 billion people experience physical water scarcity (UN-Water/FAO, 2007), while close to four billion people worldwide live under extreme water scarcity at least some months of the year (Mekonnen and Hoekstra, 2016). By 2050, the number of people living under medium and severe water stress could reach 5 billion, with water demand more than doubling for households, livestock and electricity (WWAP, 2015a). In 2015, the United Nations launched the Sustainable Development Goals (SDGs) with a roadmap to 2030 which includes objectives for clean water and sanitation (SDG 6) to “ensure availability and sustainable management of water and sanitation for all” (WWAP, 2015b). While SDG 6 is specific to water and sanitation, other goals also include water, either directly (e.g. SDG 14: Life under water, SDG 15: Life on land) or indirectly (SDG 2: Zero hunger, SDG 7: Affordable and clean energy, SDG 12: Responsible consumption and production), therefore requiring a wide range of governance strategies, measures and indicators to ensure that these goals are met.
The relation between human-beings and nature in the context of water management has evolved through the centuries, but recently this interaction has been embodied by the Integrated Water Resources Management (IWRM) and Water Security concepts, which themselves have evolved over time. The introduction of IWRM in the 1992 Dublin International Conference on Water and Development outlined the necessity to integrate knowledge about the complex physical interactions over the full water cycle (e.g., by considering surface and groundwater interactions), as well as between the water cycle and society (Savenije et al., 2014). Savenije et al. (2014) describe an evolution in IWRM towards coordinated action among stakeholders sharing water resources in a given geographic space (e.g., a river basin) and a period of time (e.g., the hydrologic year) with trade-offs to be weighted so as to “maximize the resultant economic and social welfare in an equitable manner without compromising the sustainability of vital ecosystems” following the definition from the Global Water Partnership (GWP, 2000).
Over the past decade, the concept of Water Security has been gaining attention as an important paradigm for water resources management and, in some cases, may be considered an extension of IWRM (Bakker and Morinville, 2013). In 2013, the United Nations Water Task Force on Water Security defined it as “the capacity of a population to safeguard sustainable access to adequate quantities of acceptable quality water for sustaining livelihoods, human well-being, and socio-economic development, for ensuring protection against water pollution and water related disasters, and for preserving ecosystems in a climate of peace and political stability” (UN-Water, 2013). Many other definitions have been proposed and used in specific contexts (Zeitoun et al., 2014), but more generally, Water Security implies a cross-sectoral influence of water in social, economic, ecological and political layers affecting individuals and Society. While there are many overlapping concerns between IWRM and Water Security perspectives, Bakker and Morinville (2013) describe that Water Security further implies: (1) the protection of water resources, (2) the idea of a threshold that may affect socio-ecological resilience, and (3) the necessity to respond to risks given imperfect information about water resources with an emphasis on adaptive management.
Along with the evolution of thought regarding the relationships between humans, Society and water resources is the notion of scale of action and the increasing importance of global structures affecting the water cycle. Water resources management is particular in that local management has global impacts, while at the same time, local and global forces can constrain present and future local water resources (Vörösmarty et al., 2015). Increases in extreme precipitation events and localized droughts resulting from global climate change (Hartmann et al., 2013) can affect local water availability. Local flood or physical water scarcity can affect local food production with consequences on global food prices. Likewise, inter-basin transfers, and the effects of the global economy on water quantity and quality impose additional stresses on water resources by actors that are not using local water resources directly. For instance, production and consumption activities represent a large portion of hidden water use for trade, requiring an additional consideration of water use efficiencies in distant watersheds (Hoekstra, 2010). This indirect water use (supply chain use, or water use crossing a production to consumption boundary) has important consequences in consumption and production activities, especially given that water withdrawals typically occur in stressed watersheds (Ridoutt and Pfister, 2010).
The introduction of the water footprint (WF) in 2002 (Hoekstra and Hung, 2002) brought to light an important connection between production and consumption activities and water resources. In its original definition, the WF quantifies the volumetric freshwater use of a product or a service by summing direct (or operational use) and indirect (or supply chain use) water consumption (Hoekstra et al., 2011), thereby highlighting the link between the consumption of products and the global water cycle (Hoekstra and Mekonnen, 2012a). The WF can address various aspects of SDG 12 such as: 12.2 “achieve sustainable management and efficient use of natural resources”, 12.4 “achieve the environmentally sound management of chemicals and wastes throughout their life cycle (…)”, 12.6 “encourage companies (…) to adopt sustainable practices (…)”, and 12.7 “promote public procurement practices that are sustainable (…)” (UN, 2017). When dealing with water specifically, the above goals then have repercussions for other water related SDGs (e.g., SDG 6, SDG 14) depending on how the WF is determined.
There are currently two distinct and complementary approaches to the WF, each of which follows specific steps and with a focus on water resources management and impact assessment (Boulay et al., 2013). The WF has been described as a freshwater volume which can be compared to total sustainable limits within a boundary following steps published by the Water Footprint Network (Hoekstra et al., 2011) to determine water scarcity. The WF has also been described as the result of a life cycle assessment (LCA) used to estimate potential environmental impacts of water use following the ISO 14046 standard (ISO, 2015). Despite these differences in perspectives, these WF approaches make an important connection between the physical boundary of the natural resource and the boundary of production systems. Conclusions from these WF approaches and assessments can then highlight actions that can be taken with respect to water uses following predefined objectives.
This paper proposes to combine these existing WF approaches into one harmonized WF assessment. Rather than focusing on parallel approaches as described in Boulay et al. (2013), we highlight the type of decisions that follow each assessment based on the boundaries that they cover. We propose to associate WF decision-making into two focus groups (as previously defined in Boulay et al. (2013)), based on the primary level of intervention that each decision carries on the water cycle: (1) a physical boundary represented by a hydro-geographic region (“water management-focused”) with implications on water resources management, and (2) a product system boundary with a focus on water use and impact assessment in production processes (“product-focused”). We argue for a more integrated discussion around water resources decisions as they relate to water management and products, as well as actors and their specific roles in the water cycle.
We first describe the relationship between the decision-making contexts and the most common WF approaches (Section 2) prior to merging these contexts into one harmonized WF assessment (Section 3). We then apply the proposed framework to soybean production in Mato Grosso, Brazil (Section 4), as an illustrative example of how such a harmonized assessment can benefit decision-making regarding a specific product within a given hydro-geographic region. We conclude with implications of the framework regarding policy decisions with the objective to clarify the role of each WF approach (Section 5). Our paper brings new light to prior discussions on the two main WF approaches (e.g. Hoekstra (2016); Pfister et al. (2017)). A harmonized WF assessment has the merit to clarify the role of each approach while highlighting strengths and limitations for the purposes of water decision-making for improving water resources management in river basins, and through supply chains.
Section snippets
Problem definition: multiple water footprint approaches
Current WF approaches have been applied at the product or the hydro-geographic levels for the purposes of informing water resources decision-making. These levels are inherently bound to specific water resource objectives which are important to define in order to harmonize WF approaches. In general, water is used either directly (e.g., for drinking, cleaning), or indirectly in the consumption of products or services (Hoekstra and Wiedmann, 2014). A convenient boundary to distinguish between
Goal and scope definition
Our proposed framework is inspired from prior assessments used in the two WF approaches (Hoekstra et al., 2011; ISO, 2015) and begins with the definition of the goal and scope of the study which include the study’s objectives, geographic boundary, functional unit (see below), intended audience and use of the results. The WF inventory is the starting point of the two main WF approaches, which we propose to harmonize here into a WF assessment considering the focus of each of the following steps
Volumetric water footprint assessment
Starting with the estimate of the WF inventory for one tonne of soybean in Mato Grosso (which we call here the volumetric WF (VWF) to describe exclusively water consumptive use), we identify opportunities to reduce the total volume of water required for production, as well as the conditions under which these reductions may take place. The average green VWF for soybean in Mato Grosso over the 2000–2010 period was 1590 m3 ton−1 (Lathuillière et al., 2014) with an additional 298 m3 ton−1 in the
Policy decisions resulting from the harmonized water footprint assessment
A summary of the harmonized WF assessment applied to soybean grown in Mato Grosso in 2010 is shown in Fig. 3 and Table 3 for multi-dimensional decision-making at both micro- and macro-levels. While soybean production has relied exclusively on green water resources, these resources are within sustainable limits, but could reach unsustainable limits if further agricultural expansion for soybean took place in the region. Already, this expansion has contributed to greenhouse gas emissions from land
Conclusions
This paper presents a means towards greater integration of distinct WF approaches that have been either water management- for product-focused in the context of water consumption and degradation. Our harmonized WF assessment allows for a better integration of micro- and macro-level water decisions, thereby reducing potential conflicting decisions and limitations of individual assessments. In a product-focused WF appraach, benchmark information based on environmental conditions and technology can
Declaration of interest
None.
Acknowledgments
Funding for this research was provided by the Vanier Canada Graduate Scholarship through the Natural Sciences and Engineering Research Council (NSERC)(#201411DVC-347484-257696) to MJL. Additional support was provided by the Belmont Forum and the G8 Research Councils Freshwater Security Grant G8PJ-437376-2012 through NSERC to MSJ for the project entitled “Integrating land use planning and water governance in Amazonia: Towards improving freshwater security in the agricultural frontier of Mato
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