Shoreline Changes Along the Coast of Mainland China—Time to Pause and Reflect?

Hongzhen Tian,Qinping Liu,Mengmeng Yang,Kai Xu,Joaquim I Goes,Helga Do Rosario Gomes

doi:10.3390/ijgi9100572

Abstract

Shoreline changes are of great importance for evaluating the interaction between humans and ecosystems in coastal areas. They serve as a useful metric for assessing the ecological costs of socioeconomic developmental activities along the coast. In this paper, we present an assessment of shoreline changes along the eastern coast of mainland China from ~1990 to 2019 by applying a novel method recently developed by us. This method which we call the Nearest Distance Method (NDM) is used to make a detailed assessment of shorelines delineated from Landsat Thematic Mapper (TM) and Operational Land Imager (OLI) images. The results indicate a dramatic decline in natural shorelines that correspond to the rapid increase in the construction of artificial shorelines, driven by China’s economic growth. Of the entire coast of mainland China, the biggest change occurred along the Bohai Sea, where artificial shorelines expanded from 42.4% in ~1990 to 81.5% in 2019. Over this period, this study indicates that China lost > 60% of its biological shorelines, a trend that is especially worrisome because these include areas that were once biologically diverse and extremely rich. As anticipated, shoreline losses were greatest where regions of low economic value had been transformed to areas of higher economic value. Overall, this influence of human activities on shorelines in China is unprecedented. The repercussions of these changes on ecosystems, and the susceptibility of new shoreline developments to population growth and sea-level rise, need to be assessed urgently before additional changes are effected.

Highlights

Shorelines are the interface where land, ocean, and atmosphere interact with each other [1]
We do not have clear information regarding the length and percentage of muddy shorelines that have been converted into construction shorelines. This lack of detailed information as well as other factors including rapid economic growth has hindered policymakers from effectively managing and protecting shorelines. This study addresses this shortcoming with a comprehensive study designed (1) to obtain the locations and types of shorelines along the coast of mainland China, (2) to develop a method to calculate changes between shoreline types, and (3) to analyze and quantify the characteristics of these changes
The total length of shorelines along the coast of mainland China increased by 6.9%, from 13,663.1 km to 14,611.7 km over the ~1990–2019 period primarily due to land reclamation and quay construction

Summary

Introduction

Shorelines are the interface where land, ocean, and atmosphere interact with each other [1]. Shorelines change due to natural processes, include river deposition, sediment accretion, sea-level rise, waves, tides, wind erosion, etc., and often a priori knowledge of these processes is crucial for planning anthropogenic changes to the shorelines, and for understanding both short- and long-term human impacts on the coastal environment and ecosystems [5,6]. The importance and gravity of shoreline changes have prompted a wide variety of studies worldwide. These include studies of shoreline changes in the Beaufort–Mackenzie region in Canada [7], along the coastal Ramsar wetlands in Turkey [8], along the North Sinai coast in Egypt [9], and in the Boushehr Province in Iran [10]. Remote sensing images are widely used by researchers along with geographic information systems (GIS) such as the Digital Shoreline Analysis System (DSAS) [11] to analyze the spatial and temporal changes in shorelines

Methods

Results

Discussion

Conclusion