Improving water scarcity footprint capabilities in arid regions through expansion of characterization factor methods

Abstract

Water scarcity footprint (WSF) is a recent addition to life cycle assessment methodology that has advanced the understanding of freshwater environmental impact. The Available Water Remaining (AWARE) method is one approach that has gained significant traction in WSF applications. While an effective method for determining WSF, the methodology has limitations that constrain capabilities for determining freshwater environmental impact in arid regions. The primary limitation is the inability to compare regions when more water demand exists than what is available which typically occurs in arid regions. This limitation reduces resolution and therefore decision-making capabilities. This work proposes a novel method for determining WSF in arid regions by capturing and quantifying scarcity when water demand is greater than availability. The approach presented here, called the demand to availability (DTA) method, is intended to be used for small-scale, or subregion analyses in areas where truncation occurs using standard AWARE methods. With the regional specificity, unique characterization factors can be developed to enhance deterministic resolution and ultimately improve decision-making abilities. The DTA methods are presented universally, allowing for application and implementation to any region. A case study was developed to demonstrate the effectiveness of the DTA method by analyzing characterization factors (CFs) and alfalfa WSFs in the arid Southwestern United States. Using the standard AWARE methods, this region originally truncated 38% of counties resulting in zero resolution or decision-making abilities. Results of the case study that used the proposed DTA method show an improved resolution in 100% of these counties, both within CF and alfalfa WSF. Although the proposed method is an improvement for understanding WSFs in arid regions, limitations and constraints still exist and are discussed.

Keywords: AWARE; Arid regions; Characterization factors; Life cycle assessment; Water scarcity footprint.