Comparative analysis of statistical and catchment modelling approaches to river flood frequency estimation

Abstract

The paper compares results from two approaches to the quantification of river flood frequencies applicable nationally in Britain. One approach uses both the flood peak and event‐based methods of the Flood Estimation Handbook (FEH) of current water industry practice and the other approach is a recently developed set of continuous simulation techniques using parameter‐sparse modelling of catchment flood runoff response. The methods were applied to over a hundred sites in Britain, treated as if without flow data, although such observations existed and were used only for testing purposes. Errors of ≤20% in peak flows at ungauged sites are currently very good in this hydrologically challenging context; errors of up to around 35% may have to be contended with in flood management practice. The results from the FEH statistical method reinforce its established role in peak‐flow estimation. On the basis of the aspects that have been tested here, the emerging continuous simulation approaches show considerable potential to offer good performance for peaks and flow time series. The errors associated with the FEH unit hydrograph approach reflect the additional challenge it incorporates of ungauged rainfall estimation in addition to ungauged discharge.

Flood Frequency Analysis for the Annual Peak Flows Simulated by an Event-Based Rainfall-Runoff Model in an Urban Drainage Basin

“…The estimated flood quantiles from the proposed FASAP method were approximately 10% smaller than the quantiles from the conventional design storm method, which is consistent with the research results of [2] that compare the flood quantiles using flood frequency analysis, the design storm method, and the continuous simulation method. According to research comparing the design storm method and flood frequency analysis in gauged watersheds [35][36][37], the conventional design storm method tends to overestimate the design flood. This indicates that the method in this study is appropriate to estimate design floods.…”

Modelling hydrological losses for varying rainfall and moisture conditions in South Australian catchments

“…Continuous simulation models automatically account for the antecedent conditions for major storm events, which avoid the difficulty of separately estimating the initial conditions which affect losses (Blazkova and Beven, 2009;Calver et al, 2009;Camici et al, 2011;). Continuous rainfall-runoff modelling is becoming increasingly popular because of increasing model capabilities in terms of predicting short-time interval flows and the ready availability of computer resources.…”

Tracing Temporal Changes of Model Parameters in Rainfall-Runoff Modeling via a Real-Time Data Assimilation

“…In such basins, by assimilating a limited number of relevant data from in-situ observations or remote sensing, the model performance could be substantially improved and reaches a reliable hydrological prediction [33][34][35]. This data assimilation strategy is easily used as a continuous simulation for flood frequency predictions since it accounts for various uncertainties and it employs a continuous rainfall-runoff model [58][59][60].…”