Assessing the impact factors and corresponding weights affecting the coastal morphology of Hsinchu Coast, Taiwan

This study investigates the long-term morphological pattern of the Hsinchu coast in northwestern Taiwan using three different methods: long-term isobath and shoreline change analysis, bathymetric volume change analysis, and the empirical orthogonal function (EOF) method. Our objectives include analyzing and understanding the effects of anthropogenic structures, natural processes, and their combined impacts on coastal morphological change. The shoreline analysis and bathymetric volume analysis briefly reveal that the morphological pattern of Hsinchu coast. Then, EOF analysis is applied to identify the dominant impact factors affecting the coastal morphology near the harbor, determine the weights of the impact factors, and infer the impact range of anthropogenic structures. Moreover, the EOF analysis is divided into two-time segments—namely, the periods 2005–2010 and 2017–2021—based on different bathymetric surveys and the corresponding values of impact factors. The primary and secondary EOF modes are strongly linked to the “interaction between wave and structure” and “interaction between river discharges and structure”, respectively. The spatial components of the EOF modes demonstrate that the impact range influenced by river discharges was mainly located in the northern part of the harbor, while the minimum impact range of the structures on coastal morphological interaction changes under natural factors was 3.5 km south of Hsinchu Fishing Harbor.