Yinchuan immigrant irrigation area

Yinchuan plain is an important commodity grain base in northwest China. Located between Helan Mountain and Ordos Plateau, it is a fault basin in geological structure, which is formed by long-term deposition of the Yellow River and plain lakes and swamps. From Qingtongxia to Shizuishan, including the piedmont floodplain, it is 10 ~ 50 km wide from east to west and 165 km long from north to south, covering an area of more than 7,000 square kilometers. Altitude1100 ~1200m, slowly inclines from south to north, and the ground slope varies from 0.6 ~ 1 ‰. Because of the flat terrain, deep soil layer and convenient water diversion, it is beneficial to gravity irrigation. Yinchuan Plain is located in a temperate arid area with abundant sunshine, with an average annual sunshine hours of about 3,000 hours and a frost-free period of about 160 days. Rich in heat resources, the active accumulated temperature above 10℃ is about 3300℃. The daily temperature difference is large, with an average of 65438 03℃, which is beneficial to the growth and development of crops and the accumulation of nutrients. Although there is drought and little rain (annual precipitation is about 200mm), the annual transit water volume of the Yellow River reaches more than 30 billion cubic meters, which is convenient for irrigation, and the agricultural natural resources such as light, heat, water and soil are well coordinated, providing extremely favorable conditions for the development of agriculture, forestry and animal husbandry. More than 2,000 years ago, a large number of Central Plains immigrants, together with local ethnic minorities, used the Yellow River to open canals to irrigate fields and manage agriculture and animal husbandry, becoming the earliest irrigation area in the northwest of China, known as "Jiangnan". There are famous ancient canals such as Tanglai Canal, Han Yan Canal, Huinong Canal, Qinqu Canal and Hanqu Canal. Since the 1950s, nine main canals and more than 2,000 branch canals have been built, including the West Main Canal and the East Main Canal. Tanglai Canal, located in Hexi Irrigation District, was built in the third year of Emperor Wu of the Han Dynasty (BC 102), expanded on a large scale in the Tang Dynasty and renovated after the 1950s. The canal line flows through five counties and cities, including Qingtongxia, Yongning, Yinchuan, Helan and Pingluo, with a total length of 154 km, a water diversion capacity of 160 m3/s, and more than 800 branch canals, which can irrigate more than 53,000 hectares of farmland. It is the largest self-flowing main canal for diverting water from the Yellow River in Ningxia.