A new dunetracking tool to support input parameter selection and uncertainty analyses using a Monte Carlo approach

IF 2.8 2区 地球科学 Q2 GEOGRAPHY, PHYSICAL Earth Surface Dynamics Pub Date : 2024-04-25 DOI:10.5194/egusphere-2024-579
Julius Reich, Axel Winterscheid
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Abstract

Abstract. Precise and reliable information about bedforms, regarding geometry and dynamics, is relevant for many applications – like ensuring safe conditions for navigation along the waterways, parameterizing the roughness of the riverbed in numerical models, or improving bedload measurement and monitoring techniques. There are many so-called dunetracking tools to extract this information from bathymetrical data. However, most of these tools require the setting of various input parameters, which in turn influence the resulting bedform characteristics. How to set the values for these parameters and what influence they have on the calculations has not yet been comprehensively investigated. This is why we introduce a new dunetracking tool, which is able to quantify the influence of varying input parameter settings by performing a Monte Carlo Simulation. The core of the tool is a combination of the two existing applications Bedforms-ATM (Guitierrez, 2018) and RhenoBT (Frings et al., 2012), which have been extended by adding additional features. A wavelet analysis has been adapted from Bedforms-ATM while a zerocrossing procedure and a cross correlation analysis have been implemented based on RhenoBT. The combination of both tools enables a more accurate and sound procedure, as the results of the first step are required input parameters in the second step. By performing a Monte Carlo Simulation, comprehensive sensitivity analyses can be carried out and the possible range of results is revealed. At the same time, the high degree of automation allows the processing of large amounts of data. By applying the tool to a test dataset, it was found that bedform parameters react with different sensitivity to varying input parameter settings. Bedform lengths appeared to be more sensitive (uncertainties up to 50 % were identified) than bedform heights. The setting of a window size in the zerocrossing procedure (especially for the upper layer of bedforms in case secondary bedforms are present) was identified to be the most decisive input parameter. Here, however, the wavelet analysis offers orientation by providing a range of plausible input window sizes and thus allows a reduction of uncertainties. By choosing values outside this range, divergence behavior could be observed for several resulting bedform parameters. Concurrently, the time interval between two successive measurements has proven to have a significant influence on the determination of bedform dynamics. For the test dataset, the faster migrating secondary bedforms were no longer traceable for intervals longer than two hours. At the same time, they contributed to up to 90 % of the total bedload transport, highlighting the need for measurements in high temporal resolution in order to avoid a severe underestimation.
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使用蒙特卡罗方法支持输入参数选择和不确定性分析的新型 Dunetracking 工具
摘要精确可靠的床面几何和动态信息与许多应用息息相关,如确保水道航行的安全条件、为数值模型中的河床粗糙度提供参数,或改进床面负荷测量和监测技术。有许多所谓的 Dunetracking 工具可以从水深测量数据中提取这些信息。然而,大多数这些工具都需要设置各种输入参数,而这些参数又会影响所得到的河床形态特征。如何设置这些参数的值以及它们对计算的影响尚未得到全面研究。因此,我们引入了一种新的 Dunetracking 工具,它能够通过蒙特卡罗模拟来量化不同输入参数设置的影响。该工具的核心是两个现有应用程序 Bedforms-ATM (Guitierrez,2018 年)和 RhenoBT(Frings 等人,2012 年)的组合,并通过添加其他功能对其进行了扩展。Bedforms-ATM 采用了小波分析,而 RhenoBT 则采用了零交叉程序和交叉相关分析。这两种工具的结合使程序更加准确和合理,因为第一步的结果是第二步所需的输入参数。通过蒙特卡罗模拟,可以进行全面的敏感性分析,并揭示可能的结果范围。同时,高度的自动化允许处理大量数据。通过将该工具应用于测试数据集,发现床形参数对不同的输入参数设置具有不同的敏感性。床面长度似乎比床面高度更敏感(不确定性高达 50%)。零交叉程序中窗口大小的设置(尤其是在存在次生床面的情况下对上层床面的设置)被认为是最重要的输入参数。不过,小波分析法提供了一系列合理的输入窗口大小,从而可以减少不确定性。在此范围之外选择数值,可以观察到几个结果床形参数的发散行为。同时,两次连续测量之间的时间间隔也被证明对床形动态的确定有重大影响。在测试数据集中,超过两小时的时间间隔就无法追踪到迁移较快的次级床形。与此同时,它们却占到了总基质运移量的 90%,这说明需要进行高时间分辨率的测量,以避免严重低估基质运移量。
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来源期刊
Earth Surface Dynamics
Earth Surface Dynamics GEOGRAPHY, PHYSICALGEOSCIENCES, MULTIDISCI-GEOSCIENCES, MULTIDISCIPLINARY
CiteScore
5.40
自引率
5.90%
发文量
56
审稿时长
20 weeks
期刊介绍: Earth Surface Dynamics (ESurf) is an international scientific journal dedicated to the publication and discussion of high-quality research on the physical, chemical, and biological processes shaping Earth''s surface and their interactions on all scales.
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