A Novel Method of Design Flood Hydrographs Estimation for Flood Hazard Mapping

Abstract

Flood hazard mapping requires knowledge of peak flow as well as flood wave volume and shape, usually represented as a design flood hydrograph (DFH). Statistical approaches for DFH development include nonparametric and parametric methods. The former are developed from long-term flow observations and are thus related to the physio-hydro-climatological catchment properties, but not applicable for ungauged catchments. The alternative parametric DFH can be estimated for any river cross-section, but its links with catchment characteristics are limited. The goal of this study was to introduce a novel hybrid approach for DFH estimation, where the parametric DFH is estimated from the selected properties of the nonparametric DFH (hydrograph width at the levels of 50% and 75% of the peak flow and skewness coefficient) that can be related to the catchment characteristics. The model that offers effective parameter estimation and best correspondence to the reference observation-based hydrograph was selected from among Gamma distribution, Strupczewski and Baptista candidates. The method was validated for 34 catchments of the upper Vistula River and Middle Odra water regions (Poland) based on data from the 1964–2010 period. The Baptista method was found to provide the best model for hybrid DFH construction according to the applied quality measures.

Keywords

• design flood hydrograph
• statistical methods
• parametric models
• hydrological modelling
• EU flood directive