Plan of an irrigation survey problem by Chin Chiu-Shao, 1247. The total length of the parallel canal is given as 118 li or 59 km. The irrigated fields are marked with the character tien, the major river dyke is called an, and the minor dykes cheng. Source: Needham, Joseph, (1959). Science and Civilisation in China.
Chinese practices for regulating the water supply, known as water conservation ?? (shuili), are as old