Approach for describing statistical properties of flood hydrograph

The shape of a flood hydrograph is a random event. This study develops a method for describing statistical properties of the shape of a flood hydrograph. Two shape variables, namely, shape mean (S-m) and shape variance (S-v), are defined to express the randomness of a flood hydrograph. The two-parameter beta probability density function (pdf) is adopted to represent the shape of a flood hydrograph. The parameters are estimated using the shape variables. On the basis of this approach, one can derive the design-flood hydrograph shape corresponding to various combinations of flood peak, volume, and duration. The applicability of the proposed method is demonstrated by using observed flood data from the Ashuapmushuan basin in the province of Quebec, Canada. It is concluded that the method is appropriate for representing the statistical properties of the shape of a flood hydrograph.