Historical floods of the Rhine river, reconstructed from the sedimentary fills of a dike breach pond and abandoned channels. Subtitle: Application for estimation of the design discharge.

Abstract

A data set of discharges is used to estimate the design discharge for flood protection of the rivers in the Netherlands. This discharge data set (~110 years) is too short to precisely estimate the magnitude of a possible occurring flood with a recurrence time of 1250 years, the design discharge. This study focuses on extending the discharge data set to decrease the uncertainty in estimation of extreme flood events.

Investigating grain sizes in laminated deposits stored in dike breach ponds and abandoned channels helps to determine the magnitude of floods that have occurred in the past. The study shows the relationship between the P95 content of the grain size distribution of flood deposits and associated discharges. Analysis of the sediment characteristics and the age depth curves are used to correlate the flood layers in the sediment fills to floods that occurred in historic time. Flood comparison of three locations gave insight in the impact of a historical flood. The maximum design discharge was calculated with the expansion of the discharge data set.