Remote sensing analysis of Bohai Bay West Coast shoreline changes

摘要

The Bohai Bay West Coast is a typical muddy coastal zone which is also the most sensitive and vulnerable areas in the geological, ecological environment. In recent years, human's activities are greatly affected its change's speed and direction. By using a combination of Remote Sensing and GIS technology, this paper utilizes lots of Remote Sensing data to monitor the coastline position, changes rules and influencing factors over the past 20 years. Most coastline extraction method can be used such as supervised classification, threshold extraction, object-oriented and other methods and in this paper we use the threshold extraction of water index and object-oriented approach. With the spectral index and water index, the line between the sea water and light beach is extracted whose changes can monitor the sediment deposition in real time and dynamically. The Remote Sensing methods can avoid long period difficulties and shortcomings of site visit to survey the coastal reclamation case. The results show that: (1) The coastal shoreline overall present the variation of advancing seaward. (2) The dominant factor of port construction, violation of human activities such as sea-land reclamation dominated the shoreline changes. The construction of Tianjin Lingang Industrial Area in Binhai New Area has led the coastline to the sea advanced nearly 10 km since 2005; (3) The environmental impact of shoreline changes mainly reflected in the river longer and narrower, resulting in sediment deposition to make rivers more shallower and more poor in flood discharge capacity.