Using Bayesian Statistics to Estimate Chlorine Wall Decay Coefficients for Water Supply System

Abstract

A model of pipe wall and hydraulic profile effects on free chlorine decay in a water distribution system is developed using a two-step parameter assignment method. The model employs a Bayesian statistical method and Monte Carlo Markov chain to reflect wall decay coefficients as used in EPANET and is demonstrated to provide an efficient approach for EPANET water quality model calibration. The findings indicate that the wall decay coefficients and overall decay rate are largely influenced by flow velocity, pipe diameter, and pipe roughness. The largest impacts are demonstrated on unlined cast iron pipe, and lesser impacts progressively in ductile pipe, and then polyvinylchloride pipe.