Conventional instream habitat models (e.g. Phabsim) predict the impact of regulation on the habitats of freshwater taxa in stream reaches. Analyses of their application in France and New Zealand showed that comparable results could be achieved using simplified hydraulic data (depth- and width-discharge relationships, average particle size and mean -or median- annual discharge). The resulting generalised models perform well outside their calibration range, transfer well across continents, and facilitate habitat studies over entire river networks.