Design flood hydrographs: a regional analysis based on flood reduction functions

Modern flood hazard mapping techniques and water infrastructure design require the entire flood hydrograph. However, statistical methods for flood hydrograph estimation in ungauged basins have not received the same attention as the models used to predict the peak flow value. Here the design hydrograph of an ungauged basin is reconstructed in a parsimonious way through the estimation of a non-dimensional flood reduction function (FRF). Based on data from 87 basins (763 station-years of flood hydrographs), we show that a two-parameter FRF can be efficiently estimated by multiple linear regression from the longest drainage path length and slope of the basin, the average basin elevation, the width function kurtosis and the mean value of the scaling exponent of the intensity–duration–frequency curve. Reasonable similarities between the estimated flood hydrograph and the original ones make the method suitable for extension into other areas to estimate design hydrographs in ungauged basins.