Experimental study on the impact of the second dam break heights on the evolution of two-dam failure floods

Dam-break floods, especially cascade dam-break floods, could be catastrophic and warranted further investigation to enhance understanding. This paper systematically investigated the impact of break heights of the second dam on the evolution of two-dam failure floods, comparing it with single-dam outburst floods. The experiments were carried out in an inclined rectangular flume with LiDAR technology to capture the free surface. Results indicated that a computational model for the moving hydraulic jump was developed, showing good agreement with experimental results with a relative error of about 10%. The wave height of dam-break flood increased with the increase of evolution distance. The wave front celerity (for dam spacing: L/H = 26) after the flood passed the second dam increased with the break heights. The peak discharges at the second dam site and the peak flow depth (for longitudinal coordinate: x/H = 59) both showed a linear relationship with the initial flow depth in reservoir and the break heights. An increase in the initial flow depth in reservoir or the break heights led to an increase in peak discharges and peak flow depth. This study offered constructive guidance for the risk assessment of multi-dam failure floods and disaster emergency management.