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.

Impacted by climate changes and human activities, the coastal zone of China has undergone various dramatic changes, among which, shape change of major gulfs (including bays and estuaries) is one of the most important aspects. In this paper, spatial dataset of gulf shoreline and gulf shape in seven phases since the early 1940s was delineated based on topographic maps and remote sensing imageries, and a group of indices including the ratio of natural shoreline, the shoreline utilization degree, shoreline swing direction, gulf area, gulf shape index and gulf centroid were used to analyze the spatial-temporal characteristics of gulfs in detail. It turned out that: in general, shape changes of major gulfs in the mainland of China were significant and complicated during the past 70 years, specifically, visible changes of shoreline structure, especially the decreases in both length and ratio of natural shoreline took place; the shoreline utilization degree increased remarkably because more and more natural shoreline had been artificalized; the fact that shoreline seaward shift caused by sea reclamation occurred in the majority of gulfs; spatial size (area) decreased in most of gulfs due to the fast and extensive sea reclamation; the geometric shape of most gulfs had become more complicated while the discrepancies among all the gulfs were narrowed; the centroid of most gulfs moved toward the sea; gulf-shape variations exhibited remarkable spatio-temporal differences. It is obvious that human activities, especially sea reclamation, have become the key driving force of gulf shape change since 1990. Based on the above-mentioned findings, classification management strategy based on dominant-function oriented gulf classification is strongly recommended, and gulf-based management should be strengthen in order to improve the abilities of Integrated Coastal Zone Management (ICZM) practices in China.

Data of coastal construction land around the South China Sea in 2010 and 1975 were extracted and the spatial-temporal characteristics of construction land expansion based on different geomorphologic backgrounds in this period was discussed. Results showed that: (1) In South China Mainland and Malay Peninsula, construction land in coastal zone was generally expanded rapidly; in Indochina, construction land in coastal zone was expanded moderately; in Sumatra, Kalimantan and Philippines, construction land in coastal zone was expanded slowly except Manila Bay. (2) There were significant differences in construction land expansion between different geomorphology types because of natural resources, development difficulty and hinterland area. As there were good conditions of water transport and wide hinterland, construction land in delta plain coast and estuary plain coast expanded rapidly; construction land expansion in mesa coast and barrier - lagoon coast was remarkable due to the suitability for building small or medium-sized ports; construction land expansion in gulf coast and mountain coast was relatively slow because there existed limited development potential; construction land expansion in flat dike coast was even slower because of the limited hinterland and underdeveloped water transport. (3) Development patterns varied according to coastal geomorphologic features. The spatial morphology of construction land was diverse in delta plain coast and estuary plain coast; in mountain coast, mesa coast and gulf plain coast, it presented agglomerating or zonal distribution; in barrier - lagoon coast, it presented agglomerating or star distribution; in flat dyke coast, it presented zonal, linear or point distribution.