Abstract: This study examined the spatial distribution of the continent coastline in northern China using remote sensing and GIS techniques, and calculated the fractal dimension of the coastline by box-counting method, with a time span from 2000 to 2012。 Moreover, we ana- lyzed the characteristics of spatial-temporal changes in the coastline's length and fractal di- mension, the relationship between the length change and fractal dimension change, and the driving forces of coastline changes in northern China。 During the research period, the coast- line of the study area increased by 637。95 km, at a rate of 53。16 km per year。 On the regional level, the most significant change in coastline length was observed in Tianjin and Hebei。 Temporally, the northern China coastline grew faster after 2008。 The most dramatic growth was found between 2010 and 2011, with an increasing rate of 2。49% per year。 The fractal dimension of the coastline in northern China was increasing during the research period, and the most dramatic increase occurred in Bohai Rim。 There is a strong-positive linear relation- ship between the historical coastline length and fractal dimension (the correlation coefficient was 0。9962)。 Through statistical analysis of a large number of local coastline changes, it can be found that the increase (or decrease) of local coastline length will, in most cases, lead to the increase (or decrease) of the whole coastline fractal dimension。 Civil-coastal engineering construction was the most important factor driving the coastline change in northern China。 Port construction, fisheries facilities and salt factories were the top three construction activi- ties。 Compared to human activities, the influence of natural processes such as estuarine deposit and erosion were relatively small。79098

Keywords: coastline; fractal dimension; remote sensing; spatial-temporal change; northern  China

1Introduction

Coastal areas are unique environments in which atmosphere, hydrosphere and lithosphere come into contact with each other (Faik et al。, 2009), which are extremely sensitive to global change。 The coastline not only marks the sea-land boundary but also contains a wealth of coastal  environmental  information。  Changes  in  coastlines  directly  affect  the  resources of

intertidal flats; moreover, these changes will cause variations in a variety of resources and ecological processes in coastal areas that will finally affect the survival and development of coastal residents (Cai et al。, 2002; Tao, 2006)。 Therefore, the study of coastline changes and their driving factors is of great significance for understanding not only ecological environ- mental variations in coastal zones but also global changes (Yu et al。,2003; Ou et al。, 2004; Sabyasachi et al。, 2009; Antonio et al。, 2010)。 The repetitive acquisition and synoptic capa- bilities of remote sensing systems have been exploited to provide timely spatial data for coastal geographical information systems, enabling detection and monitoring of coastline movement (Kevin and Hesham, 1999; Dellepiane et al。, 2004; Elizabeth et al。, 2005; Li et al。, 2010; Sun et al。, 2011; Li et al。, 2012; Chu et al。,  2013)。

This paper aimed to analyze the spatial and temporal characteristics of coastline varia- tions of northern China。 The visual interpretation method was employed to extract the spatial and temporal distribution information of the coastlines at six time points (2000, 2005, 2008, 2010, 2011, and 2012), box-counting method was applied to calculate the fractal dimensions of the coastlines, the driving factors of the observed spatial and temporal variations of the coastlines were also analyzed。 The range of coastlines studied begins at the Yalu River Estu- ary in Liaoning Province and ends at the junction of Shandong Province and Jiangsu Prov- ince, ranges from 117°30´E to 124°20´E in longitude and from 35°05´N to 41°N in latitude (Figure 1)。 The study area encompasses the whole Bohai Bay Economic Rim in northern