Informed-Parameter versus Hydrologic Model-Chain Approaches for Flood Quantile Estimation

Two approaches, namely the informed-parameter approach and the hydrologic model-chain approach, are widely used to estimate future flood quantiles while accounting for nonstationarity. In the informed-parameter approach, changes in flood quantiles are estimated by conditioning distribution parameters on physical covariates, including meteorological forcings, anthropogenic drivers, and large-scale climate modes. On the other hand, for the model chain approach, meteorological forcings are fed into the hydrological model to simulate flood peaks, which are subsequently used to estimate flood quantiles.

Both approaches have distinct advantages and limitations, such as the multiple linkages involved in the model-chain approach and the relatively simplified process representation in the informed-parameter approach. These characteristics strongly influence the uncertainty associated with flood quantile estimates. However, direct comparisons between these two widely used approaches remain limited. This study presents a preliminary comparative assessment of the informed-parameter and hydrologic model-chain approaches, focusing on how uncertainty propagates into future flood quantile estimates. Overall, the findings of this study aim to support stakeholders in understanding the challenges associated with each approach and in selecting the most suitable method for a given region.