LAUSR

Morphological change in the Qinzhou Bay (QZB), southwest China, has been studied, using bathymetric charts and remote sensing data. Historical admiralty charts were digitized and analyzed in a Geographical Information System (GIS) environment to provide quantitative estimates of underwater topography changes for exploring the accretion-erosion characteristics from 1960s to 2010s. Multi-temporal satellite images have been used to analyze the coastline developments. The results showed that the bathymetry and coastline of QZB changed dramatically in recent decades. The subaqueous area decreased by about 8% in the study area during the last 50 years, mainly due to coastal land reclamation. The average growth rate of the coastlines was 2.07 km/yr. between 1978 and 2013 with natural curvy coastlines being replaced by straighter artificial shorelines. During the period from 1960s to 1990s, the evolution of QZB was mainly governed by natural factors with slight deposition or erosion in the deep troughs. From 1990s to 2010s, intensive large-scale human activities, such as port building, channel dredging and artificial island construction became the main causes affecting morphological changes in the QZB. Approximately half of the underwater terrain had undergone significant changes (greater than ±0.5 m), and the proportion of deposition area accounting for 32.26% of the subaqueous area, about twice more than erosion area. Large scale reclamation projects have made dramatic negative impact on coastal natural ecosystem. Integrated coastal zone management need to be carried out to maintain the balance between economic development and ecological health.