Abstract: The propagation of dam break flood and its influence on cities in the downstream are important issues in dam safety research. In this paper, the inundation process of downstream cities were simulated and analyzed through numerical approach. A mountain river in south China with four cascaded reservoirs was selected as case study. The simulation was conducted with multiple dam break modes. Results suggest that the inundation speed and maximum inundated area are closely related to the maximum dam break discharge, i.e., related to the water head and size of the breach. The time required for maximum inundated area is related to the distance between city and reservoir. The speed as well as inundated area and inundated volume in the case of single break are less severe than those caused by successive cascaded break flood, which, however, floods and recedes dramatically. The duration of the inundation process for a city is related to the volume of the reservoir rather than to maximum break discharge.

Key words: cascade reservoirs, dam break flood, inundated area, dam break discharge, inundation duration