人类活动对港湾岸线及景观变迁影响的比较研究————以中国象山港与美国坦帕湾为例

利用多时期遥感数据,以10年为时间步长,提取1985-2015年4个时期中国象山港和美国坦帕湾的岸线空间位置,长度和曲折度以及港湾地区景观构型,多样性和破碎度等信息,构建海岸人工化和港湾景观人工干扰指标,探讨人类活动对港湾岸线,景观演变的影响.结果表明:① 近30年来,象山港和坦帕湾自然岸线长度不断缩减,人工岸线长度呈先增后稳定的态势.由于两地人类活动方式的差异,象山港局部岸段形态发生剧烈变化,岸线曲折度不断变小;而坦帕湾岸线形态变化较小,岸线曲折度几乎保持不变.② 1985-1995年,象山港海岸人工化不断加强,1995年以后有所减弱,但人类活动的影响范围逐渐变大,几乎遍及整个港湾海岸.1985-2015年,坦帕湾海岸人工化强度虽有加强,但增幅缓慢,海岸人类活动也主要集中于各沿海城市区域.③ 1985-2005年,象山港和坦帕湾各人工化强度等级样区景观平均斑块面积总体呈减少趋势,但2005-2015年,象山港各强度样区景观平均斑块面积变化趋势不一,坦帕湾各强度样区变幅则较为平稳.④ 1985-2005年,象山港各强度样区景观多样性指数逐渐增大,而坦帕湾变化不一;2005-2015年,两港湾人工化强度由弱至强,景观多样性指数先增后减.⑤ 1985-2005年,象山港和坦帕湾不同人工化强度样区,景观破碎度指数逐渐增大;2005-2015年,两港湾景观破碎度指数呈减小趋势.

Comparative research on the impact of human activities on changes in coastline and landscape in bay areas: A case study with Xiangshangang Bay,China and Tampa Bay,USA

Using multitemporal Landsat TM images at a 10-year interval, in this study, we (1) extracted information of spatial location, length, and tortuosity of coastline and landscape configuration, diversity and fragmentation in the bay areas of Xiangshangang Bay, China and Tampa Bay, USA as well from the four 10-year periods from 1985 to 2015; (2) constructed indices of artificial coastline and bay area landscape human disturbance; and (3) explored and discussed the impact of human activities on changes in bay area coastline and landscape types. Our analysis results demonstrate the following five points. (1) In the past 30 years, the length of natural coastline in Xiangshangang Bay and Tampa Bay was shrunk, while the length of their artificial coastline was first elongated and then showed a stable trend. Since there was a difference influence of human activities on coastline and landscape types between the two bay areas, Xiangshangang Bay experienced dramatic changes in parts of coastline geomorphologies and continuous decrease of coastline sinuosity while in Tampa Bay, there was a little change in coastline geomorphologies and its coastline sinuosity was almost unchanged. (2) The intensity of human activities in Xiangshangang Bay was continuously enhanced from 1985 to 1995, and then the degree of enhancement had slowed down after 1995. However, in the time period, the impacted extent of human activities gradually increased and finally covered almost entire coastline in the area. In Tampa Bay area, although the intensity of human activities was enhanced, the degree of enhancement was slow from 1985 to 2015 and the impacted area of human activates was concentrated in several coastal city areas. (3) The average area of landscape patches strongly disturbed by human activities in both Xiangshangang Bay and Tampa Bay generally showed a trend of decreasing from 1985 to 2005. However, during the period of 2005-2015, the mean patch area of landscape disturbed by different degree of human activities in Xiangshangang Bay changed differently, while in Tampa Bay it basically unchanged. (4) From 1985 to 2005, the indices of landscape diversity in various areas of human disturbance in Xiangshangang Bay gradually increased, while in Tampa Bay, changes in indices of the landscape diversity varied. From 2005 to 2015, the change in the intensity of human disturbance in both bay areas was from weak to strong while the indices of landscape diversity in Xiangshangang Bay and Tampa Bay increased first and then decreased. (5) Landscape fragmentation index in different human disturbance areas in both Xiangshangang Bay and Tampa Bay gradually increased from 1985 to 2005 while from 2005 to 2015, in both bay areas, the landscape fragmentation index presented a decreasing trend.