Different Approaches for Calibration of an Operational Water Distribution System Containing Old Pipes

Model of a water distribution system (WDS), containing old pipes, requires calibration to estimate the roughness of old pipes. Pipe roughness increases with age. In some cases the estimated roughness of old pipes, using optimization procedures based on measurements in operational WDS, can be quite high. Therefore it would be proper to use real diameters of the old pipes instead of high roughness values. The aim of the paper is to compare different approaches of calibration in such case. Five different calibration methods are analysed changing pipe roughness, diameter or both. Calculations have been conducted for an operational WDS. Measurements in the WDS indicated that there are quite large differences in the dynamics of demands (even for the same customer categories) in different zones of the system. It is shown that this has strong influence on the calibration results.