“…In addition, with the development of portable laser spectroscopy, DVE-LS is increasingly used in an in situ, non-destructive manner to track water movement through the subsurface (Gaj et al, 2016;Pratt, Lu, Barbour, & Hendry, 2016;Rothfuss, Vereecken, & Brüggemann, 2013;Volkmann & Weiler, 2014). Due to the cost-effectiveness and portability, DVE-LS has been used increasingly in a variety of applications (Baer, Barbour, & Gibson, 2016;Harrington, Gardner, Smerdon, & Hendry, 2013;Quade et al, 2019). Although previous work has been paramount in advancing our understanding of water movement through the subsurface, two key issues still remain unanswered.…”