Nearshore Monitoring With X-Band Radar: Maximizing Utility in Dynamic and Complex Environments
Nearshore Monitoring With X-Band Radar: Maximizing Utility in Dynamic and Complex Environments
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DOI：
10.1029/2020jc016841
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发表时间：
2021-04-01
影响因子：
3.6
通讯作者：
McCann, D. L.
中科院分区：
文献类型：
--
作者：
Atkinson, J.;Esteves, L. S.;McCann, D. L.
沿海管理和工程应用需要量化近岸水深测量变化的性质和大小的数据。然而，由于高成本和复杂的后勤工作，水深测量通常很少见。这项研究表明，陆基X波段雷达提供了一种成本效益高的手段，可以在相对较高的频率和较大范围内监测近岸变化。开发了一种新的数据质量和处理框架，以减少雷达水深测量估计中的不确定性，并使用索尔佩内斯(英国)18个月安装的数据进行了测试。除数据校准和验证外，还整合了两个新要素，以减少数据散布和离群值的影响：(A)自动选择“良好数据”的周期；(B)应用深度记忆稳定器。在波高为1米的条件下，在40×40米的空间分辨率下，雷达测深的精度为+/-0.5米(95%的可信区间)。在索比内斯，在3周至6个月的时间尺度上观察到雷达衍生的水深变化超过了这一误差。这些数据能够量化近岸沉积物在频率和空间复盖范围内的变化，这是其他方法难以获得的和/或昂贵的。结果表明，在短短几周的时间尺度上发生的近岸泥沙移动量与该地区报告的年沿岸输移率相当。雷达的使用可以对近海水深测量的变化提供早期预警，这些变化可能会影响脆弱的沿海地区。
Coastal management and engineering applications require data that quantify the nature and magnitude of changes in nearshore bathymetry. However, bathymetric surveys are usually infrequent due to high costs and complex logistics. This study demonstrates that ground-based X-band radar offers a cost-effective means to monitor nearshore changes at relatively high frequency and over large areas. A new data quality and processing framework was developed to reduce uncertainties in the estimates of radar-derived bathymetry and tested using data from an 18-months installation at Thorpeness (UK). In addition to data calibration and validation, two new elements are integrated to reduce the influence of data scatter and outliers: (a) an automated selection of periods of "good data" and (b) the application of a depth-memory stabilization. For conditions when the wave height is >1 m, the accuracy of the radar-derived depths is shown to be +/- 0.5 m (95% confidence interval) at 40 x 40-m spatial resolution. At Thorpeness, radar-derived bathymetry changes exceeding this error were observed at time scales ranging from 3 weeks to 6 months. These data enabled quantification of changes in nearshore sediment volume at frequencies and spatial cover that would be difficult and/or expensive to obtain by other methods. It is shown that the volume of nearshore sediment movement occurring at time scale as short as few weeks are comparable with the annual longshore transport rates reported in this area. The use of radar can provide an early warning of changes in offshore bathymetry likely to impact vulnerable coastal locations.