A quantitative approach to monitoring new sand cay migration in Nansha Islands
- PDF / 930,753 Bytes
- 6 Pages / 595 x 842 pts (A4) Page_size
- 36 Downloads / 161 Views
A quantitative approach to monitoring new sand cay migration in Nansha Islands ZHU Haitian1, 2, 3*, JIANG Xingwei1, 2, MENG Xuelian3, FENG Qian2, CUI Songxue2, LIANG Chao2 1 Institute of Remote Sensing and Digital Earth, Chinese Accodemy of Sciences, Beijing 100094, China 2 National Satellite Ocean Application Service, Beijing 100081, China 3 Department of Geography & Anthropology, Louisiana State University, Baton Rouge, Louisiana 70803, USA
Received 9 February 2015; accepted 13 April 2015 ©The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2016
Abstract
Sand cay is a special kind of islet formed by coral detritus and bioclast, which is common in Nansha Islands of China. Some sand cays play an important role in ocean strategy and economy, but surprisingly we know little about them, especially those recently formed sand cays. In this research, we monitor migration of a new sand cay in Nanxun Jiao (Gaven Reef) using a series of QuickBird and WorldView-2 satellite images between June 2006 and August 2013. We conduct a regression between migration distance and wind observational data to examine the migration patterns of the new sand cay. The migration distance is calculated based on the sand cay locations extracted based on Normalized Difference Water Index (NDWI). The wind observational data downloaded from NOAA are reformed into four wind direction vectors. Based on the results of regression, we concluded that the migration of the new sand cay on Nanxun Jiao was significantly associated with the east, west and north wind. East wind was the main influence factor of the migration; its impact strength was almost twice as the west and north wind. The south wind has little effect on the migration of the sand cay, which is partly blocked by the artificial structure in the south. Key words: Nansha Islands, new sand cay, migration pattern, remote sensing, high resolution, linear regression Citation: Zhu Haitian, Jiang Xingwei, Meng Xuelian, Feng Qian, Cui Songxue, Liang Chao. 2016. A quantitative approach to monitoring new sand cay migration in Nansha Islands. Acta Oceanologica Sinica, 35(3): 102–107, doi: 10.1007/s13131-016-0827-8
1 Introduction Located in South China Sea (SCS), Nansha Islands (also called the Spratly Islands) is a well-known archipelago composed of hundreds of islands, reefs and shoals. Nansha Islands have abundance of natural resources such as fish, oil and natural gas, and is one of the busiest areas for maritime shipping. Sand cay is a special islet composed of coral detritus and bioclast, which are accumulated by broken debris from the coral reef and kept from being carried away from the platform by waves (Encyclopædia Britannica Inc, 2015). Some sand cays evolve over a long period of time and have functioned as sailing land marks such as those have appeared in Genglu Bu (a sailing direction written by ancient Chinese seaman) since Ming Dynasty (1368–1644), indicating an existence of more than 300 a (Liu, 1995). In recent years, new sand cays are developing on the coral reef
Data Loading...
