Proposal of Parameter Range that Offered Optimal Performance in the Coastal Morphodynamic Model (XBeach) Through GLUE

Abstract

<i>The process-based XBeach model has numerous empirical parameters because of insufficient understanding of hydrodynamics and sediment transport on the nearshore; hence, it is necessary to calibrate parameters to apply to various study areas and wave conditions. Therefore, the calibration process of parameters is essential for the improvement of model performance. Generally, the trial-and-error method is widely used; however, this method is passive and limited to various and comprehensive parameter ranges. In this study, the Generalized Likelihood Uncertainty Estimation (GLUE) method was used to estimate the optimal range of three parameters (gamma, facua, and gamma2) using morphological field data collected in Maengbang beach during the four typhoons that struck from September to October 2019. The model performance and optimal range of empirical parameters were evaluated using Brier Skill Score (BSS) along with the baseline profiles, sensitivity, and likelihood density analysis of BSS in the GLUE tools. Accordingly, the optimal parameter combinations were derived when facua was less than 0.15 and simulated well the shifting shape, from crescentic sand bar to alongshore uniform sand bars in the surf zone of Maengbang beach after storm impact. However, the erosion and accretion patterns nearby in the surf zone and shoreline remain challenges in the XBeach model.</i>

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“…There is also a non-stationary mode called surfbeat, that simulates the short wave variations on the wave group scale and their associated long waves. Using this mode, in agreement with the literature (Rutten et al, 2021;Bae et al, 2022), is it possible to simulate the beach response to the incoming waves with a more realistic onshore transport in the surf zone minimising the shoreline recession. The third mode is the non-hydrostatic one, which resolves individual waves, but it was discarded in this study due to its high computational cost.…”

Morphological Changes in Storm Hinnamnor and the Numerical Modeling of Overwash

“…Consequently, the offshore sediment transport and morphological changes were overestimated under typical beach conditions. 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.…”

“…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.…”

Smartphone Digital Image Processing Method for Sand Particle Size Analysis

“…예를 들면, 백사장의 연안 침식을 평가하는 방법으로 평행해 빈단면(Equilibrium Beach Profile) 모델에서 모래의 입도는 해빈 단면의 형태와 외해 또는 해빈 방향으로의 모래 거동을 결정하는 요소로 사용된다 (Dean, 1977). 또한 Xbeach 모델 은 해빈의 퇴적물 이동을 수치모의하는데 모래의 평균입경을 기준으로 퇴적물 이동 산정식을 결정한다 (Bae et al, 2022; **한동대학교 공간환경시스템공학부 학부학생(Undergraduate Student, School of Spatial Environment System Engineering, Handong Global University) **한동대학교 공간환경시스템공학부 조교수(Corresponding author: Se-Hyeon Cheon, Assistant Professor, School of Spatial Environment System Engineering, Handong Global University, 558 Handong-ro, Buk-gu, Pohang, Kyeongbuk 37554, Korea, Tel: +82-54-260-1424, Fax: +82-54-260-1429, shcheon@handong.edu) Jin et al, 2020;McCall et al, 2014;Oliveira et al, 2020).…”