Open-flow canals are large distributed systems characterized by non-linear, time-varying and dependent with the operating point behavior. These systems can be suitably represented for control by linear parameter varying (LPV) models. In this paper, two ways of obtaining an LPV model for a single reach open canal are proposed and compared: an LPV integrator delay zero (IDZ) model based on hydraulic laws and an LPV model based on identification techniques. The first approach is a white-box modeling approach while the latter is a grey-box methodology using experimental data. Finally, they will be applied and compared in a test-bench canal.