A gravity trunk still running
Tang-Lai is the largest gravity irrigation trunk in the Ningxia Yellow River irrigation area. The present canal is 314 kilometres long. Its design intake is 127 cubic metres a second. It draws Yellow River water at the Qingtongxia works in Wuzhong, upstream of the capital, and runs on through Wuzhong, Yinchuan and Shizuishan. Tree lines follow the water where it crosses the city. Inside Yinchuan, four west-bank trunks form the irrigation skeleton: the Western Trunk, Tang-Lai, Huinong and Han-Yan. Through the urban area, a stretch of 75 kilometres runs between Xingqing District and Jinfeng District. Between those districts the cut is still a working canal, with water in it and trees along it, fitted into a street plan that grew up beside the flow.
A Song name, a Yuan repair, a 2017 list
A Song history already names Tang-Lai at Xingzhou, today's Yinchuan, and at Lingzhou. The characters now written Tang-Lai are a later spelling; the 1927 Shuofang gazetteer is the first use of those modern characters. Guo Shoujing repaired the canal in 1264, a date the Yuan history carries. The Ningxia irrigation area begins in the Western Han Yuanshou years, late in the second century BCE, and Song sources again name Tang-Lai and Han-Yan at today's Yinchuan and Lingwu. Huinong Canal was opened in 1726 to water land east of Han-Yan. The old operating cycle was plain: gates sealed, water rationed, and the fields at the canal tail watered after the fields above them. On 10 October 2017, at an executive meeting of the International Commission on Irrigation and Drainage in Mexico City, the Ningxia ancient Yellow River irrigation area was inscribed on that commission's World Heritage Irrigation Structures list. The listing is an ICID World Heritage Irrigation Structure. It is not a UNESCO World Heritage inscription. The heritage named that day is the regional irrigated area. Tang-Lai is one trunk inside it, and the canal is still carrying water. Since 1998 it has also sent ecological water to lakes that include Shahu, in Pingluo County, Shizuishan, 42 kilometres from Yinchuan.
Where the river passes, and where the lakes are
Through Yinchuan the Yellow River runs 83.8 kilometres, the length fixed in December 2021. The river enters at the boundary of Litong and Lingwu and leaves at the boundary of Helan County and Pingluo County, passing Lingwu, Yongning County, Xingqing District and Helan County. East of the channel lie the Qin Canal, the Han Canal and the Donggan Canal. West of it, Tang-Lai and the other trunks continue north. Residents meet this water in town as canals and lakes. Diannong River, also called the west-bank main drain, was built from 2003 to 2008. It runs 108.5 kilometres inside Yinchuan and links lakes that include Yuehai, in Jinfeng District. A person at Yuehai is looking at water from this system, held in a city lake rather than at the main embankment. The intake remains upstream, at Qingtongxia in Wuzhong. The reach itself ends where Helan County meets Pingluo, and the canal water that continues to Shahu has already crossed into another city.