Wade–Giles romanization Han Shui, Pinyin Han Shui, one of the most important tributaries of the Yangtze River of China. It has a total length of about 952 mi (1,532 km). The Han Shui rises in the Shen-ch'iung Shan (mountains), part of the Mi-t'sang Shan in the north of Ning-ch'iang County in the extreme southwest of Shensi Province. Its upper stream is known successively as the Yü-tai Ho, the YangShui, and, below Mien-hsien, the Mien Shui. At Han-chung it becomes the Han Shui. It flows eastward at the foot of the Tsinling Shan, receiving from the north various tributaries (of which the Hsun Ho is the largest) and a large number of north-flowing tributaries arising in the Ta-pa Mountains to the south. This upper valley of the Han Shui is mostly rugged and mountainous, but around Han-chung is a fertile alluvialbasin some 60 mi (100 km) long and 12 mi (19 km) wide. Below An-k'ang the river cuts through a series of deep gorges and emerges eventually into the central Yangtze Basin at Kuang-hua (Lao-ho-k'ou) above Yün-hsien in Hupeh Province.
The lower course of the Han Shui flows through a rich lowland. The course changes frequently, and the area is so flat that a small change in the level of the river may inundate a considerable area, and extensive dikes are required. Above Hsiang-fan at Chün Hsien, where the Han Shui receives the Tan Chiang (river), a dam completed in 1970 stabilizes the water flow, prevents flooding, extends the range of navigation, and permits irrigation. Six hydroelectric generators began operation on the site between 1968 and 1973. Further downstream at Hsiang-fan the river receives its largest tributary, the Pai-shui Chiang. In the 1950s, in order to prevent flooding, a largeretention basin was built at the confluence of the Pai-shui Chiang to accumulate floodwaters and to regulate the flow of the Han Shui itself; four extensive irrigation projects were also built in the area.
Below Hsiang-fan the Han Shui meanders south and then turns eastward to join the Yangtze at Wu-han. In this lower course much of the river's water is dispersed into the innumerable creeks and lakes of the southern section of the North China Plain. Toward its junctionwith the Yangtze, the river narrows sharply. This area, too, has been prone to frequent and disastrous flooding, and, to prevent this, in 1954 a second retention basin was built south of the junction with the Yangtze.
The Han Shui is an important waterway. The lower course of the river, with its innumerable small waterways and canals, forms the spine of a dense network of water transport covering the whole southern part of the North China Plain; junks can travel from Sha-shih to Wu-han by these waterways—a much shorter distance than along the main stream of the Yangtze.