Analysis of Spatial and Temporal Shoreline Changes and Reclamation in the Qinzhou Bay and the Manila Bay
Over the past 40 years, significant changes have occurred along the coastlines of Qinzhou Bay in China and Manila Bay in the Philippines. Understanding the patterns of these changes is important for the management and planning of coastal zones. This study is based on the Google Earth Engine platform...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | zho |
| Published: |
Editorial Committee of Tropical Geography
2025-03-01
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| Series: | Redai dili |
| Subjects: | |
| Online Access: | https://www.rddl.com.cn/CN/10.13284/j.cnki.rddl.20240441 |
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| Summary: | Over the past 40 years, significant changes have occurred along the coastlines of Qinzhou Bay in China and Manila Bay in the Philippines. Understanding the patterns of these changes is important for the management and planning of coastal zones. This study is based on the Google Earth Engine platform, using the modified normalized difference water index, combined with the Otsu algorithm and the Digital Shoreline Analysis System, to extract the coastlines of Qinzhou Bay in China and Manila Bay in the Philippines over the past 40 years, and then analyze the spatiotemporal variation characteristics of the two coastlines and the situation of reclamation. The results show that in the past 40 years, the coastline of Qinzhou Bay has generally advanced towards the sea, with a coastline length increase of 44.78 km, an average End Point Rate(EPR)of 6.81 m/a, and average Linear Regression Rate(LRR)of 6.16 m/a. Natural coastline length continued to decrease, whereas the proportion of artificial coastlines continued to increase. The Index of Coastline Utilization degree (ICUD) values show an upward trend, whereas the Index of Coastline Type Diversity (ICTD) values show a continuously decreasing trend. The Manila Bay coastline first increased and then decreased, with an overall decrease of 1.05 km—a relatively small change. The coastline also shows a trend of advancing towards the sea with an average EPR of 2.36 m/a and average LRR of 2.32 m/a. The proportion of natural coastlines continued to decline, whereas that of artificial coastlines gradually increased. The ICUD values showed a steadily increasing trend, whereas the ICTD values showed a downward trend. The cumulative area of reclamation in Qinzhou Bay has reached 6,674.27 hm2, with an average annual expansion rate of 196.30 hm2/a. Reclamation activities were significantly active and large-scale. However, the cumulative reclamation area of Manila Bay is only 1,718.59 hm2, with an average annual expansion rate of 50.55 hm2/a, indicating relatively limited reclamation activities. The reclamation intensity index and annual spatial expansion rate of Qinzhou Bay were higher than those of Manila Bay. Overall, compared to Manila Bay, the Qinzhou Bay coastline exhibited more significant characteristics in terms of change amplitude, change speed, and reclamation intensity. Reclamation activities have a significant impact on coastline changes, and port and dock construction and aquaculture are the main driving factors for reclamation. |
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| ISSN: | 1001-5221 |