Source: adapted from Delfs, R. (1990) "Arteries of the Empire", Far Eastern Economic Review, 15 March 1990, pp. 28-29
Grand Canal System
The Grand Canal system (or Da Yun He) represents a remarkable achievement of imperial Chinese hydraulic engineering. At its peak during the Ming dynasty (1368-1644 AD), the system totaled about 2,500 kilometers with Beijing at its northernmost extension, Hangzhou at its southernmost point and Luoyang at its easternmost point. It thus connected the political center of the empire in the north (especially from the Song dynasty; 960 AD), with the economic and agricultural centers of central and southern China. This was mainly achieved by linking two of China's most important river basins, the Yellow River (Huang He) and the Yangtze River (Chang Jiang). North of the Yangtze, the canal must ascend a gradual slope to an elevation of more than 40 meters. To insure safe circulation, a system of locks (the Chinese are attributed to the first lock ever built in 983), feeder lakes and lateral canals was constructed. Under such circumstances, the control of an unified China became a possibility and the Grand Canal is acknowledged to be a significant element in the economic and political stability of imperial China, mainly through grain distribution.
The canal is the expression of a long history of engineering projects to control river systems and provide irrigation. Due to its hydrography, movements are easier on its a East - West axis, while North - South communications were more arduous. The initial course of the canal, completed around 605 AD by the Sui dynasty (581 - 618 AD), was providing a much needed North - South axis by connecting several sections constructed at earlier times, starting from the Wu Kingdom era (486 BC). The initial goal of canal construction, which would change little through time, was shipping agricultural commodities through the empire, notably to the capitals. For the Sui dynasty, the goal was to link their western capital, Luoyang, to the rich agricultural regions of the lower Yangtze. The capital of the Tang dynasty (618 - 907 AD), Chang'an (Xi'an) was further west along a tributary of the Yellow River, but linked to the Grand Canal. For the Yuan / Mongol (1279 - 1368 AD) and Ming dynasties, the Grand Canal linked the Northern Capital (Beijing) to southern China, enabling rice grown in southern China to supply the wheat growing regions of the north.
It is however south of the Yangtze Delta that the density of the canal system was the highest. Along the Yangzhou - Suzhou - Hangzhou trunk line every town of importance was linked to a complex system of canals creating a unique economic and social system where a large amount of wealth was derived from canal trade. At its peak during the 15th and 16th centuries, about 400,000 tons of grain transited on the canal each year. However, during the Qing dynasty (1644 - 1911) the canal gradually fell into disrepair and some sections were abandoned. A major change in the course of the Yellow River in 1855 cut the Grand Canal in two sections. By the first half of the 20th century, the canal was no longer functioning in a coherent manner. Today, the canal is about 1,700 kilometers in length and is still heavily used in the Yangtze delta. About 100,000 river vessels transit on the canal each year, carrying about 260 million tons, mostly construction material. The canal thus offers an alternative to move ponderous goods which otherwise could not be handled effectively by China's transport system.