AbstractA partial blockage usually results in undesirable consequences for long-distance conduits. In order to study the disturbance of partial blockages on transient responses, a numerical model was developed to simulate a partial blockage based on the traditional method of characteristics (MOC). The transient responses were simulated using the proposed numerical model for the water supply conduit with a partial blockage. Based on the equivalent resistance conditions, the distribution of extreme pressures was compared to reveal the disturbance characteristics of the partial blockage. The simulation results show that the disturbance of the extreme pressure is the strongest around the blockage site, and decreases linearly with the distance to the blockage. Subsequently, a diagnosis model was established to detect the zone and the intension of the partial blockage, based on the distribution of the extreme pressures of the transient responses. The results show that the diagnosis model has good performances, irrespective of locations or intensions, with a maximum error of about 2%. The proposed approach can be properly used to detect the zone and the intension of the partial blockage in a single long-distance conduit.