I was really hoping this article was going to discuss how Rome was somehow more open or prone to invasions due to their water networks. Instead, I was treated to the fairly unexciting conclusion of Rome traded a lot, causing its various regions to be interdependent, therefore possibly vulnerable because of additional risks inherent in relying on a trade network to supply your city with food.
great tl;dr
The article has so little to do with ancient history it's staggering. It's the "conceptual drought modelling" equivalent of a woodworker trying to drum up attention for his range of kitchen cabinets by saying "they're the kinds of cabinet I think Justin Bieber would like".