A systematic comparison of statistical and hydrological methods for design flood estimation

Accurate estimates of design floods are useful for the planning and design of hydraulic structures or the quantification of risks that will arise due to the occurrence of floods. Hydrological literature is replete with numerous ways of estimating design floods and these methods are considered to be either statistical or hydrological. The statistical method (commonly referred to as flood frequency analysis) refers to the fitting of a probability distribution function to records of annual maximum flows at a gauging location. The fitted distribution function is then used to estimate the design flood corresponding to a chosen frequency of occurrence often expressed as a return period. While the hydrological method for design flood estimation refers to the use of a rainfall-runoff model that represent the processes accounted for in the transformation of precipitation to runoff. Given that hydrological and statistical methods are commonly used in research and applied hydrology, the goal of the current study was focused on evaluating the performance of both methods in terms of accuracy and variance of errors in the estimates. The results of the numerical experiments show that both methods under- and outperform each other depending on the performance measure of interest. Following the precautionary principle, it is suggested that both methods be used in any real application since both methods are based on consolidated theories.

Full reference:

Okoli, K., Mazzoleni, M., Breinl, K., Di Baldassarre, G. (2019). A systematic comparison of statistical and hydrological methods for design flood estimation. Hydrology Research, nh2019188, https://doi.org/10.2166/nh.2019.188

Link to the paper

By Kaycee Okoli

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