| Laizhou Bay is influenced both by the human and natural factors. The natural factors contain changes of yellow river estuary and tidal surge, and the human factors consist of breed aquatics, coastal engineer and beach mining. To exactly know the facts of shoreline changes of Laizhou Bay and study the impacts of natural and human factors on the shoreline changes is very important for protection and management of Laizhou Bay coastal zone.In this study, we use 1978-2009 four Landsat images and field data to build interpretation keys of shoreline based on color, texture and adjacency of land objects. Furthermore, the extraction principle of bedrock shoreline, sandy shoreline, silty mud shoreline and artificial shoreline is put forward.We extract the location, length and types of Laizhou Bay shoreline of 1978, 1989, 2000 and 2009, and analyze the distributions of shoreline. The results indicate that the shoreline increased 31km in the past 31 years by the rate of averaged 6.0 km/a. The shoreline went forward 95922.4 hm2 with the rate of 3094.3 hm2/a and fallen back 49.3 hm2 with the rate of 1.6 hm2/a. We also discussed the 31 years evolutions of shoreline types. The results indicate that the shoreline was changing from natural shoreline to human shoreline.Based on the extraction information and additional data, we analyzed the reasons of shoreline changes. The major reason is that the yellow river changed its route and the changes of sediment transportation conditions. However, winds, waves and the acceleration of sea level also lead to the changes of shoreline. The construction of saltern and breed aquatics led to the changes of west and south shoreline. But the major reason of east shoreline changes is that construction of ports and breed aquatics and mining. The waves, tidal surge and acceleration of sea level also influenced the changes of shoreline. Based on these analyses, we put forward decision-makings and advices to the protection and management of shorelines. |
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