Estimating instantaneous peak flow from mean daily flow data

Estimation of the design flood flow for hydraulic structures is often performed adjusting probabilistic models to daily mean flow series. This may cause an underdesign of the structure capacity with possible risks of failure, because instantaneous peak flows may be considerably larger than daily averages. Estimation of the instantaneous peak flows is often needed for simulation of the reservoir operation based on the hydraulic characteristics of the structures and the operation rules. Because there is often a lack of instantaneous flow data at a given site of interest, the peak flow has to be estimated. This paper develops a new method to estimate the instantaneous peak flow from mean daily flow data. This methodology was successfully applied to a series of flow information from gauging stations in Brazil, with important improvements compared to the traditional methods available in the literature.