Discontinuities in geomorphic dam-break flows

Abstract

Geomorphic dam-break flows have been shown to feature discontinuities other than the downstream progressing wavefront. Of particular importance is the jump that forms, for some combinations of initial conditions and bed materials, near the location of the dam. No attempts to characterize this jumpwere undertaken until recently. In this text, the discontinuities occurring in geomorphic dam-break flows are investigated in the framework of a shallow-flow theory. The main objective is to understand whether they are susceptible to be described by Riemann waves or if they are flow features aroused by momentum sources, namely friction, or by phenomena beyond the shallow-flow theory. For that purpose, experimental results are presented and compared with a theoretical solution of the governing equations given initial discontinuous data. The classification of the discontinuities follows the comparison between the observed and calculated flow features for the same initial conditions. No attempt is made to address the phenomenological aspects of the formation and evolution of the discontinuities. Nevertheless, the observed behavior is discussed in conjunction with the weak solution of the governing equations.