Monitoring long-term shoreline dynamics and human activities in the Hangzhou Bay, China, combining daytime and nighttime EO data

Abstract

Shorelines are vulnerable to anthropogenic activities including urbanization, land reclamation and sediment loading. Shoreline changes may be a reflection of the degradation of coastal ecosystems because of human activities. Understanding the shoreline dynamics is, therefore, a topic of global concern. Earth observation data, such as multi-temporal satellite images, are an important resource for assessing changes in coastal ecosystems. In this research, we used Google Earth Engine (GEE) to monitor and map historical shoreline dynamics in the Hangzhou Bay in China where the Qiantang River flows into the East China Sea. Specifically, we aimed to capture and quantify both the spatial and temporal shoreline changes and to assess the link between anthropogenic activities and shoreline changes on the integrity of this coastal area. We implemented a Tasselled Cap analysis (TCA) on Landsat imagery from 1985 to 2018 in GEE to calculate the wetness coefficient. We then applied Otsu method for automatic image thresholding on the wetness coefficient to detect waterbodies and shoreline changes. Further, we adopted the nighttime light data from the Defense Meteorological Satellite Program's Operational Linescan System (DMSP-OLS) from 1992 to 2013 as a proxy of human activities. The results show that in the hotspot areas, the shoreline has moved by more than 5 km in the last decades, accounting for approximately 900 km 2 of land accretion. Within this area, the human activity, indicated by the intensity of nighttime light, increased significantly. The results of this work reveal the influence of human activities on the shoreline dynamics and can support policies that promote the sustainable use and conservation of coastal environments. Our methodology can be transferred and applied to other coastal zones in various regions and scaled up to larger areas.

Assessing the impact of bridge construction on the land use/cover and socio-economic indicator time series: A case study of Hangzhou Bay Bridge

“…Water was reclaimed not only for impervious land but also for agricultural areas (94 km 2 during the pre-bridge period, 110 km 2 in the post-bridge period). This land reclamation was most prominent around the shoreline of Ningbo, and it has been noted in a previous study on Hangzhou Bay (Chu et al 2020). In addition, a large area of water changed into wetland (380 km 2 pre-bridge, 439 km 2 post-bridge), of which some also changed back into water (203 km 2 pre-bridge, 207 km 2 post-bridge).…”

Quantifying Dynamic Coupling Coordination Degree of Human–Environmental Interactions during Urban–Rural Land Transitions of China

“…Construction land is highly related to scopes of human socioeconomic activities. The NTL data was used to identify urban and rural areas [52]. The percentage…”

Integrating Different Databases to Offer a Geological Perspective of Coastal Management: A Review Case from the Northern Tuscany Littoral Cell (Italy)

“…Moreover, both natural and human-induced changes in the coastline position over time have undermined socio-economic stability and economic growth [6]; they are now perceived as a danger to institutions and citizens. Numerous studies have been carried out about the comprehension of coastal morphodynamic mechanisms, spanning from natural settings to sites where human-induced climate change variations have strongly affected the environment [7][8][9][10][11][12][13][14]. These studies are often focused on a present-day time-scale (tens of years), though they do not take into account that (i) the current situation is also a result of the inherited history from the past centuries, and (ii) the last century is itself the result of geological sedimentary cycles that occurred thousands and tens of thousands of years ago.…”