Sensitivity Analysis of Event-Specific Calibration Data and Its Application to Modeling of Subaerial Storm Erosion under Complex Bathymetry

Abstract

Key parameters in a process-based model depicting the morphological changes during storm events should be adjusted to simulate the hydro- and morphodynamics, leading to site-, profile-, and event-specific calibration. Although area models eliminate variability in calibrated parameters along with each profile in complex bathymetry, the amount of influence datasets with different wave conditions have on model performance is still unclear in an area model in a given parameter space. This study collected hydrodynamic and bathymetric field data over four different storm conditions (two single and two cluster storms) at Maengbang Beach, South Korea. The numerical model XBeach was adopted using four storm datasets with four key parameters to examine the influence of event-specific calibration data on subaerial storm erosion. When using clustered storm data, a relatively limited number of parameter combinations showed higher model sensitivity to different parameter sets as opposed to single storm data with the same parameter sets. Model sensitivity to different storm events was correlated with cumulative storm power and resultant erosion volume in comparison with other features in the datasets. The results are expected to guide the selection of an event-specific dataset with various morphological and hydrodynamic factors in an area model under complex bathymetry.

Morphological Changes in Storm Hinnamnor and the Numerical Modeling of Overwash

“…To address this limitation, ongoing discussions focus on various parameter calibration methods [3,4,12,13]. In this study, a trial-and-error approach was employed based on the parameters proposed in previous studies [5] along with additional parameters, with the aim of simulating overwash during storm events.…”

“…In XBeach, facua is denoted as a coefficient associated with the phase shift between intrawave sediment suspensions and orbital flow. In previous studies [5], facua was used. A comparison with the sets of facSk and facAs was conducted in this study.…”

“…To assess this impact, a survey was conducted using unmanned aerial vehicles (UAVs), which revealed significant erosion at the front of the beach and deposition due to overwashing at the back. In this study, the XBeach model [2], which is effective for simulating erosion caused by storms on sandy beaches [4][5][6], was employed to simulate both erosion and overwash-induced deposition. XBeach was originally developed to simulate the collapse of barrier islands on dissipative beaches, and its default parameters have been criticized for overestimating offshore sediment transport [7].…”

“…Because of the model's inherent nonlinearity and its reliance on empirical formulations, a proper parameter calibration is essential for obtaining accurate results. Various calibration methods have been proposed in previous studies [4,5,8]. However, the trial-and-error method, which typically relies on the experience and knowledge of model users, is commonly used.…”

“…They suggested a more effective simulation of erosion by correlating it with the average slope angle. In their study of multiple storm events in XBeach simulations, Jin et al showed that the sensitivity of facua was the highest, significantly influencing the model's accuracy [5]. Therefore, this research aims to compare and analyze the results of separating facua into facAs and facSk, not only in terms of the erosion caused by overwash, but also for the resultant deposition.…”