The historical process of the masonry city walls construction in China during 1st to 17th centuries AD

Quantitative study on the three-dimensional defense of Puzhuang Suo-Fort ancient wall and the moat

The spatial layout of the coastal forts defense system of the Ming Dynasty of China has been studied in a relatively comprehensive way. Nonetheless, ancient defense mechanisms have not been fully revealed. Previous studies have focused more on the macro and meso levels. Studies into its microscopic construction mechanism need to be enhanced. This research attempts to quantify and validate the rationality of the ancient microscopic defense mechanism, using the ancient defense mechanism of Pu Zhuang Suo-Fort in Zhejiang Province as an instance. This study concentrates on the distribution of firepower strength beyond the walls of coastal defense forts, as well as the effect of wall height on firepower defense capabilities. There is a specific firepower attenuation area near the walls due to the firing blind area in the coastal forts defense system. And the construction of the moat plays an additive role in its defensive capability. Meanwhile, the height of the fort wall will also affect the range of the firing blind zone under Yangmacheng. In theory, there is a reasonable height range of the wall and a proper position of the moat. This height range can meet both good economy and defensive capabilities. In turn, the position of the moats and the height of the walls can verify the rationality of the construction mechanism of the coastal forts' defense system.

Population, Wars, and the Grand Canal in Chinese History

Throughout Chinese history, the Grand Canal served as a regional infrastructure in facilitating socio-economic and political development. The core regions of each dynasty were located in China’s eastern plain, and the Grand Canal ran from south to north through the plain, connecting northern and southern China. In unison, the areas along the Grand Canal also suffered from frequent wars. The role of the Grand Canal in influencing regional stability has yet to be sufficiently explored in the literature. This study seeks to (1) figure out the spatial distribution of population and wars, and (2) quantitatively measure the relationship between wars, population, and the distance from waterways in the Grand Canal Area in AD752–1910 by using their high-resolution geo-referenced data. Kernel density analysis was employed to serve the first purpose, while Pearson correlation and curve estimation analyses were applied to serve the second. Our results show that the areas surrounding the Grand Canal were densely populated. There was a war hot zone in the Beijing–Luoyang–Nanjing region near the Grand Canal, which shifted gradually over time. The correlation between war and population densities was positive, whereas the correlation between war density and distance from the waterway was negative. Finally, the cubic model captures the non-linear relationship between population, wars, and waterways. The above findings may shed more light on the Grand Canal’s role in influencing regional population and war patterns in historical China, a topic that has received little academic attention. More importantly, they may help advance empirical understanding of the impact of large-scale infrastructure on regional sustainability.

Understanding Urban Growth in Beijing-Tianjin-Hebei Region over the Past 100 Years Using Old Maps and Landsat Data

Studying urban expansion from a longer-term perspective is of great significance to obtain an in-depth understanding of the process of urbanization. Remote sensing data are mostly selected to investigate the long-term expansion of cities. In this study, we selected the world-class urban agglomeration of Beijing-Tianjin-Hebei (BTH) as the study area, and then discussed how to make full use of multi-source, multi-category, and multi-temporal spatial data (old maps and remote sensing images) to study long-term urbanization. Through this study, we addressed three questions: (1) How much has the urban area in BTH expanded in the past 100 years? (2) How did the urban area expand in the past century? (3) What factors or important historical events have changed the development of cities with different functions? By comprehensively using urban spatial data, such as old maps and remote sensing images, geo-referencing them, and extracting built-up area information, a long-term series of urban built-up areas in the BTH region can be obtained. Results show the following: (1) There was clear evidence of dramatic urban expansion in this area, and the total built-up area had increased by 55.585 times, from 126.181 km2 to 7013.832 km2. (2) Continuous outward expansion has always been the main trend, while the compactness of the built-up land within the city is constantly decreasing and the complexity of the city boundary is increasing. (3) Cities in BTH were mostly formed through the construction of city walls during the Ming and Qing dynasties, and the expansion process was mostly highly related to important political events, traffic development, and other factors. In summary, the BTH area, similarly to China and most regions of the world, has experienced rapid urbanization and the history of such ancient cities should be further preserved with the combined use of old maps.