A BIVARIATE ANALYSIS OF THE VOLUME AND DURATION OF LOW-FLOW EVENTS

The knowledge of the volume and duration of low-flow events in river c hannels is essential for water management and the design of hydraulics structures. In this study, both preceding characteristics, X-1 and X- 2, are considered simultaneously via two types of bivariate distributi ons whose marginals are exponential. One of these bivariate distributi ons has been presented by Nagao and Kadoya (1971) and the other has be en used by Singh and Singh (1991) to the study of rainfall intensity a nd rainfall depth. The results are applied to the low-flow series (''p eaks-below-threshold'') of Lepreau River (station 01AQ001) in New Brun swick, Canada. These results show that the model that was successfully employed by Singh and Singh (1991) to study rainfall, presents certai n difficulties when a very strong correlation, rho, between the two ra ndom variables XI and X2, exists. The model by Nagao and Kadoya (1971) seems to be more satisfactory for such situations, although this mode l seems also to be quite sensitive to variations in rho.