Coastal Vulnerability of the Macrotidal and Heavily Engineered Coast in Fujian, China

Abstract

Fujian has one of China’s most tide-dominated and heavily engineered coasts, yet no segment-scale vulnerability assessment exists. We assessed 2449 km of mainland shoreline in 1 km segments using the classic six-variable coastal vulnerability index, from public data. Change rates came from thirty annual Landsat-based shorelines, giving a complete index for 2293 segments. The very high vulnerability class (defined by provincial quartiles) is predominantly concentrated in Putian (51.9 percent) and Quanzhou (42.8 percent). Those differences follow shoreline type. Eighty percent of the remaining 115 km of sandy shore is very high, against 53 percent of rocky shore in the low class. An exact decomposition gives each segment a dominant contributor from tide in Ningde to waves in Zhangzhou. Thirty percent of the 1.70 million people within 1 km of the coast live behind the very high quarter. Eleven sensitivity runs move individual segments, but none breaks the link to shoreline type, and Putian and Quanzhou lead even without the rate variable. The two published conventions for scoring tidal range rank different prefectures first, and each matches a different hazard. The storm-framed convention leads with Zhangzhou, where 99.7 percent of the province’s 2020 storm-surge damage fell.