Advancing nearshore wave monitoring: estimating parameters through video time stack imagery
摘要
Hydrodynamic parameters such as significant wave height, period, and breaking wave height are vital for understanding nearshore processes, designing coastal structures, supporting navigation, and improving wave forecasting. However, long-term wave data collection in nearshore zones is challenging due to extreme weather risks and the high cost of marine instrument deployment. Although remote sensing provides an alternative, its accuracy is often limited by image resolution and weather constraints. Shore-based video monitoring offers a cost-effective solution, enabling continuous, high-resolution wave data acquisition. This study presents the first deployment of a Video-Beach Monitoring System (VBMS) on the east coast of India, installed on a 35 m tower, covering a 1.2 km alongshore and 1 km cross-shore field of view at Rushikonda beach. Camera calibration was done using Caltech’s toolbox, and rectified products snapshot, Timex, and time stacks were generated using CIRN’s Quantitative Coastal Imaging Toolbox (QCIT). Wave analysis was carried using a 20-minute cross-shore time stack images, which are filtered (0.05–0.5 Hz) to enhance wave signals. Wave heights were estimated from intensity transitions, and wave periods derived using the zero-crossing method. Validation against in-situ data showed strong agreement with observations from a deployed directional wave and tide recorder in October 2022 and from a nearby wave rider buoy data in December 2022. For Hs, correlation of 0.764 and 0.796, RMSEs of 0.12 m and 0.09 m, and bias of 0.09 m and 0.02 m were observed in October and December, respectively. For Tp, RMSEs of 0.71 s and 1.12 s, bias of 0.52 s and 0.63 s, and correlation 0.817 and 0.846 were recorded. These results confirm the accuracy and applicability of VBMS in monitoring nearshore wave dynamics under diverse conditions.