Effect of observation errors on the uncertainty of design floods

This study investigates the uncertainty in the estimation of the design flood induced by errors in flood data. We initially describe and critically discuss the main sources of uncertainty affecting river discharge data, when they are derived using stage-discharge rating curves. Then, different error structures are used to investigate the effects of flood data errors on design flood estimation. Annual maxima values of river discharge observed on the Po River (Italy) at Pontelagoscuro are used as an example. The study demonstrates that observation errors may have a significant impact on the uncertainty of design floods, especially when the rating curve is affected by systematic errors.

► This study investigates the uncertainty in the estimation of the design flood induced by errors in flood data.
► The paper illustrates the “rating curve paradox”, where the use of perfect model with imperfect data amplifies the overall uncertainty.
► This study demonstrates that observation errors may have a significant impact on the uncertainty of design floods.