Design Flood Hydrograph Based on Multicharacteristic Synthesis Index Method

Flood events consist of flood peaks and flood volumes for various durations that are mutually correlated and need to be described by multiple variables. Conventional flood frequency analysis methods are generally based on the univariate distributions of either flood peaks or flood volumes, and hence only provide a limited assessment of flood events. In this paper, a multicharacteristic synthesis index (MSI) method is developed to describe flood hydrographs in an integrated way by considering the multiple characteristics synthetically, such as flood peak, 1-day maximum flood volume, 3-day maximum flood volume, 7-day maximum flood volume, etc. Annual maximum flood hydrograph series are sampled and then are transformed into corresponding MSI series by the MSI method. The quantile of the MSI series corresponding to a specified design return period is estimated by conventional flood frequency analysis method. A procedure for derivation of design flood hydrograph based on the MSI quantile is proposed. An application at the Geheyan reservoir in China is given. Results show that the MSI method can provide a new way for derivation and reassessment of design flood hydrographs.