I didn't read the entire study but I'm a speed reader and skimmed it quickly to understand the methodology used for the study. It was sound. I also examined the pages with the charts referenced by
@curious2garden to see the actual results of the study.
I also read the conclusion on page 80:
"the general principles demonstrated here indicated that reduced water use, consistent irrigation frequency measured through 68 cVPD and no flushing of the root zone are elements of a desirable irrigation management strategy for cannabis."
Now this was not a peer reviewed scientific study but a thesis. The author did obtain their Masters in Environmental Science and has an impressive resume so I'm going to go with the data provided in that paper over the cannabis science from people that are not scientists.