The Canal That Carried the Grain

The North Canal is the northern approach to Tianjin, and its course can be stated precisely. It runs 186 kilometres from Tongzhou to Tianjin, passing through Xianghe County in Hebei and then through the Wuqing, Beichen, Hebei and Hongqiao districts of the municipality before joining the Hai River at Sanchahekou. Because it is part of the Grand Canal, it belongs to a system that connected the Yangtze with the capital, and the Northern Canal is described as the northern terminus of that Beijing-Hangzhou system. Everything the plain districts of Tianjin became, they became along this line of water.

Grain moving north needed places to stop, and the towns of the northern plain are those places. Yangcun in Wuqing was an ancient grain wharf before it was a district seat. Beicang means the northern granary, and took its name from the storehouses that served the capital after the Yuan moved there. Even Sanchahekou, where the canal meets the Hai, was settled early: under the Jin a fort called Zhigu was set up where the North and South canals meet the river, and that is the earliest administrative settlement recorded in Tianjin. A canal does not only carry goods; it leaves a row of settlements at every point where a boat could tie up.

Modern management of the canal is a matter of gates. The Beiguan flood-diversion hub on the North Canal has a barrage, a flood gate, a grain-inspection tower, a connecting channel and a wetland, and its purpose is to take water off the canal when it rises. Through the hub, water from the North Canal can be released into the Yunchao diversion river and so into the Chaobai, and the structure controls a catchment of more than four thousand square kilometres. The grain-inspection tower is a small reminder that this was an administrative waterway long before it was an engineering one: somebody once had to check what was on the boats.