近60年莱州湾东部砂质海岸地貌的时空动态

Spatial and temporal dynamics of sandy coastal geomorphology in the east of Laizhou Bay over recent 60 years

在野外考察的基础上,以不同时期测量和成像的海图、地形图和高分辨率遥感影像为数据源,综合使用数字岸线分析、遥感、地理信息系统等方法,对近60年来莱州湾东部砂质海岸(界河口-刁龙嘴)地貌演变进行研究。结果表明,研究期内莱州湾东部岸线迁移和水下岸坡冲淤存在强烈的时空差异。岸线迁移表现为冲淤进退交替发生,其在时间过程上具有非线性的显著特点。1959-2013年,侵蚀岸线所占比例波动起伏,具有阶段性。侵蚀岸段年均演变速率以1985年为界分成两个阶段,前期由极大值4.95m/a(1959-1969年)锐减至极小值1.97m/a(1969-1985年),后期由1.97m/a增大到4.43m/a(1985-1998年),之后均处于高强度侵蚀。岸线迁移空间分布的差异性主要表现在4个岬湾的岸线变迁特征与莱州湾东岸岸线整体变迁并不一致。同时,水下岸坡冲淤条带大体相间分布,同一岸段1959-1985年和1985-2008年的冲淤演变趋势基本相反。进一步分析表明最近60年来,莱州湾东部砂岸在水库拦沙、潮上带工厂化水产养殖、大型海岸工程等人类活动的地貌效应共同控制下,发生了5次岸线淤积前进与侵蚀后退以及冲淤速率大小的交替。

Based on the results of field surveys, the spatial and temporal dynamics of sandy coastal geomorphology along the eastern Laizhou Bay over the last 60 years was investigated using the comprehensive methods of digital shoreline analysis, remote sensing and geographic information system technologies. The data mainly derived from the nautical charts, topographic maps and high resolution remote sensing images which measured and imaged in different periods. The results show that there are significant spatial-temporal variations in both the sandy coast shoreline migration and the subaqueous slope erosion-deposition evolution along the eastern Laizhou Bay. The al- ternate regulation of forward and backward for shoreline migration is caught in this study. There is a remarkable non-linear characteristic in the time process. The proportion of the erosional shoreline is fluctuated and phased from 1959 to 2013. The average annual evolution rate of eroded coast is divided into two stages by 1985. The erosion ratedecreased from the maximum value of 4.95 m/a （during the period of 1959-1969） to minimum value 1.97 m/a （1969-1985） at prophase. In the late period, the erosion rate increased from 1.97 m/a to 4.43 m/a （1985- 1998）, and the coast was in serious erosion state since then. The characteristics of shoreline migration in four head- land bays are not consistent with overall trend. At the same time, the scouring strips distribute alternating with the silting of the subaqueous slope. The trend of scouring and silting evolution was basically opposite in the same coast between the periods of 1959-1985 and 1985-2008. Further analysis indicate that there are 5 alternations of ero- sion and deposition and the changes of rate of erosion and siltation, under the control of geomorphic effects of an- thropogenic activities such as sediment trapping by reservoirs, fishing culture in supratidal zone and coastal engi- neering, in the east of Laizhou Bay during recent 60 years.