Six diversion dams in Shar-Chai, Nazlu-Chai, and Baranduz-Chai rivers in Urmia plain, Urmia, Iran, were selected to investigate their safety against piping. The analytical model was based on a PIPING code based on Sellmeijer’s design formula and a propabilistic method. A sensitivity analysis was undertaken using collected prototype and laboratory data to investigate the model’s compatibility and accuracy. The model produced reasonable results at the end of this analysis. The selected diversion dams were then analyzed for their probability of failure due to piping. The results were compared with the predetermined target probabilities of failure and showed safe configurations for most of the selected dams.
The partial safety factors for Sellmeijer’s design formula were calculated to be used when designing water-retaining structures for piping in Urmia region. The comparison of the Sellmeijer’s method with the empirical methods of Bligh and Lane showed that the Sellmeijer’s method requires a shorter seepage length and produces a more economical design for water retaining structures.