Assessment of uncertainty of unit hydrograph and its implications in hydraulic structure designs

In many hydraulic designs and analyses, the design storm is often convolved with the unit hydrograph (UH) to obtain a design flood based on which the performance of hydraulic system is examined. However, due to the errors in processing rainfall and runoff data, model inadequacy, and other factors the UH derived by any method involves uncertainty. With the presence of uncertainty in UH, the design flood event also subject to uncertainty. In this paper, the methodologic framework of uncertainty analysis of UH is presented along with a numerical example. In addition, the implications of such uncertainty in the design and performance evaluation of a hydraulic structure are discussed. (Authors)