Long-term monitoring and evaluation of land development in a reclamation area under rapid urbanization: A case-study in Qiantang New District, China

Land reclamation has occurred extensively worldwide to accommodate urbanization and economic development, especially in developing countries like China. However, we have a limited understanding of the long-term dynamics and key drivers of land use/cover change in the reclaimed area. In this study, we monitored the detailed spatiotemporal evolution of land reclamation from 1973 to 2018 in Qiantang New District using time-series LANDSAT and SENTINEL-2A images and then compared the differences of landscape changes between reclaimed, which are the new-built land from Qiantang River, and inland areas. Key findings include: (1) A significant decreasing trend for areas near the Qiantang River along the coastline (212.21 to 80.99 km(2)) and an increasing trend for constructed land (10.05 to 120.89 km(2)) from 1973 to 2018 was detected; (2) The development modes of the inland area and reclaimed area were significantly different. Development in the inland area was similar to other Chinese cities, whereas the reclaimed area was relatively complex with two main changing paths; and (3) Year 2008 was an important turning point in the perspective of urbanization in the study area. Before 2008, urbanization was random and uncontrolled. After 2008, new governance on land appeared and changed the landscape into a compact and uniform pattern. The proposed framework should reveal the detailed trajectory of land reclamation in small areas and provide insights and tools for better understanding the impact of human activities on the landscape pattern in coastal regions under rapid urbanization.