Dam break flow through rigid-emergent vegetation

Abstract

Dam failures pose a significant threat to life and property. This study investigates the potential of rigid emergent vegetation to attenuate dam break waves, reducing their destructive impact. Experiments explored the effect of varying vegetation field lengths on wave propagation. Wooden cylinders with consistent diameter (1.0 cm) and density (0.067) simulated the rigid vegetation in a straight, flat rectangular channel. Four different vegetation lengths and three bore conditions for different reservoir and tailwater depths were examined to analyze their influence on dam break wave behavior. The results demonstrate the effectiveness of vegetation in dissipating wave energy, leading to a rapid decrease in wave height and celerity. Interestingly, increasing vegetation length significantly attenuates the wave height downstream of the vegetation zone, while having no significant impact on the reflection wave height upstream of the vegetation. This finding highlights the targeted effectiveness of strategically placed vegetation in shielding downstream areas. The study also clarifies that celerity can be calculated using shallow water equations for both upstream and downstream regions with wave height and tailwater depth. However, within the vegetation, drag forces significantly reduce celerity. A novel equation, derived from wavefront profiles, was proposed and validated to accurately calculate celerity within the vegetation field. These findings provide valuable data for validating numerical models simulating dam break wave interactions with vegetation.