Estimation of debris-flow volumes from storm events

The present paper is a contribution for the correct formulation of the problem of the determination of the total volume of solid material, which, after being mobilised as a debris flow, deposits on the debris fan of a torrent during a single storm event. The paper consists of two parts. In the first part, the knowledge on the subject is reviewed and the main variables and parameters an recognised (including the pluviometric index of the debris-flow triggering rainfall events), so that a functional relationship among these variables is proposed for debris volume prediction. In the second part, a mathematical expressions obtained, by which the order of magnitude of the solid volumes deposited on a debris fan during an event may be obtained by means of variables and parameters which the phenomenon depends on.