Several approaches have been attempted for more systematical uncertainty quantification (UQ) of pipeline transient wave propagation. Considering the uncertainties on pre-transient (steady-state) pressure or flow velocity, the polynomial chaos expansion (PCE; Sattar & El-Beltagy, 2017) and the method of distributions (Alawadhi et al., 2018) are respectively employed to model the uncertainties of transient pressure. However, the methodologies in (Alawadhi et al., 2018; Sattar & El-Beltagy, 2017) use, explicitly or implicitly, the property that the transient wave varies linearly with the steady-state pressure and flow velocity, thus cannot