Bayesian analysis of stage-fall-discharge models for gauging stations affected by variable backwater

Parsimonious stage-fall-discharge rating curve models for gauging stations subject to backwater complications are developed from simple hydraulic theory. The rating curve models are compounded in order to allow for possible shifts in the hydraulics when variable backwater becomes effective. The models provide a prior scientific understanding through the relationship between the rating curve parameters and the hydraulic properties of the channel section under Study. This characteristic enables prior distributions for the rating curve parameters to be easily elicited according to site-specific information and the magnitude of well-known hydraulic quantities. Posterior results from three Norwegian and one American twin-gauge stations affected by variable backwater are obtained using Markov chain Monte Carlo simulation techniques. The case studies demonstrate that the proposed Bayesian rating, curve assessment is appropriate for developing rating procedures for gauging stations that are subject to variable backwater. Copyright (C) 2009 John Wiley & Sons, Ltd.