Water Accounting and Vulnerability Evaluation (WAVE): Considering Atmospheric Evaporation Recycling and the Risk of Freshwater Depletion in Water Footprinting

Abstract

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.

The WULCA consensus characterization model for water scarcity footprints: assessing impacts of water consumption based on available water remaining (AWARE)

“…In previous midpoint methods, this varied from two orders of magnitude (0.01-1) for Pfister et al (2009) andBerger et al (2014), and up to 5, 7, and 9 orders of magnitude for Boulay et al (2011b), Hoekstra et al (2012), and Swiss Eco-Scarcity method (Frischknecht et al 2008), respectively, excluding the zero values. This was an important choice which was made with the thresholds placed along the distribution curve in order to keep as much of the natural distribution as possible yet fix the tailing values to the maximum and minimum (see Fig.…”

“…While water withdrawal comprises the total water input into a product system, water consumption is defined as the fraction of water withdrawal which has become unavailable for the originating river basin users due to evapo(transpi)ration, product integration, or discharge into other basins and the sea. Hence, subsequently, methods based on water consumption-to-availability (CTA) ratio were developed, with the reasoning that water withdrawn from the environment and released in the same watershed (for cooling purposes for example) does not generally contribute to local water scarcity (Boulay et al 2011c;Hoekstra et al 2012;Berger et al 2014) (even if local impacts may occur between the withdrawal and release points (Loubet et al 2013)). Outcomes from expert discussions within WULCA (Boulay et al 2015a) first identified the need to transition from WTA and CTA towards a demand-to-availability ratio (DTA), in order to better answer the overarching question identified above (Boulay et al 2014) since both ecosystem water demand and human consumption are considered in Bdemand.^The proposal was accepted by a panel of 48 LCA experts from academia, industry, and governmental institutions (Boulay et al 2015a) with, however, one main limitation identified, in addition to the challenge associated with quantifying ecosystem water demand.…”

“…While the AWARE modeling requires an intrinsic cut-off, it does not include additional modeling, such as a logistic curve as done previously in other methods (Pfister et al 2009;Boulay et al 2011b;Berger et al 2014). This avoids the additional arbitrary choice of curve fitting and thresholds (different than cutoffs, discussed below), which were originally used to define water scarcity or stress, based on WTA (Alcamo et al 2000;Vorosmarty et al 2000).…”

EU Product Environmental Footprint—Mid-Term Review of the Pilot Phase

“…Though this is acknowledged, we do not really understand why non-robust LCIA methods cannot be exchanged by better-existing ones already now (e.g., water and resource depletion)-adding an additional impact category during the ongoing pilot phase was obviously possible. More suitable LCIA methods for water depletion are the methods of Pfister et al [23] and Berger et al [24] and for resource depletion the method of Schneider et al [25,26], which have been available since 2009, thus before the PEF method was published. Furthermore, updating the impact assessment methods only after all 24 PEFCRs are finalized should automatically lead to an invalidity of these PEFCRs as the determined relevant impact categories might not be valid anymore.…”

Water Use Efficiency Improvement against a Backdrop of Expanding City Agglomeration in Developing Countries—A Case Study on Industrial and Agricultural Water Use in the Bohai Bay Region of China

“…Miano et al [80] considered the influences of climate and human change factors on regional water resources exploitation. Based on local water resource deficiency, Berger et al investigated the possibility of water degradation from perspective of water consumption [81]. Boulay et al believed WSI is the competition pressure among water users, and differentiated water sources and water quality [82].…”