Perturbation Solution for Dam‐Break Floods

A solution for the complete and instantaneous collapse of a dam in a prismatic, infinitely‐long sloping channel is found by using the method of matched asymptotic expansions. The outer solution is a kinematic‐wave approximation, and an inner solution that includes a depth‐gradient term in the momentum equation is calculated for the region near the moving kinematic shock front. The reservoir is modeled with a point mass source, and the solution is believed to become asymptotically valid after the shock front has advanced about four reservoir lengths downstream. A comparison with experiment shows good qualitative agreement, but more comparisons with experiment should be made in order to assess the qualitative accuracy of the solution.