There is a small amount of snow water supply in the spring above Zhenjiang Pass in the main stream of Minjiang River, and the seasonal variation of runoff in the year corresponds to the rainy season. When a large-scale rainstorm occurs or spreads with the flood peaks and the flood peaks of the main stream overlap, the peak height of the main stream is high, which seriously threatens the safety of the middle and lower reaches. The average annual runoff in the upper reaches of Minjiang River is about 654.38+0.8 billion cubic meters at Zhenjiangguan Hydrological Station in Songpan County and increased to 654.38+0.45 billion cubic meters at Zipingpu Hydrological Station in Dujiangyan City. Water diversion irrigation at Pengshan Hydrological Station in the middle reaches 14 1 100 million cubic meters. With the integration of the lower reaches of Minjiang River into Dadu River, the water volume of the main stream has soared, and the annual average runoff of Wutongqiao Hydrological Station not far below the confluence is about 78 billion cubic meters. Gaochang Hydrological Station, Minjiang Control Station 29 kilometers away from the estuary, has an average annual runoff of about 89 billion cubic meters for many years. The measured maximum flow of the main stream is: Zipingpu Station 5480 m3/s (1964), Pengshan Station1kloc-0/600m3/s (1984) and Wutongqiao Station 35300m3/s (/kloc-0). According to the flood survey, in July 19 17, a large-scale rainstorm occurred in the middle and lower reaches of Minjiang River, including Qingyi River, and a historical flood occurred in the main stream. The estimated peak flow is: Pengshan Station 15 100 cubic meters per second; Wutongqiao Station is 54,000 cubic meters per second; The water level of Gaochang Station is 295.75m, and the flow rate is 5 1000m3/s ... The flood and dry flow rate of Minjiang River also changes greatly, and the dry flow rate of Zhenjiang Customs Station is generally less than 20 m3/s. Zipingpu Station is 90 cubic meters per second; Pengshan Station is 30m3/s; Wutongqiao Station is 400 cubic meters per second; The high station is 450 m3/s, and the minimum flow of the high station over the years is 364 m3/s (1980). The Minjiang Estuary has an average annual flow of 2,850 cubic meters per second and an annual runoff of 90 billion cubic meters.

The sediment content of Minjiang River is relatively small. According to the statistics of Levin Station, the average sediment concentration for many years is 0.58kg/ m3, and the average sediment transport for many years is 5265438+ 10,000 tons, including 32.97 million tons in Dadu River, accounting for 63.2%. Qingyi River is nearly 9 million tons, accounting for 17.3%. The bed load of Minjiang River is mainly produced in the upper reaches, with a large amount, large particle size, concentration within the year and great interannual variation. Dadu River is the main sediment-producing area in Minjiang River Basin, with an average annual sediment transport of 810.2 million tons in Zipingpu Station, 37.84 million tons in Wutongqiao Station and 52.6 million tons in Gaochang Station.

With the rapid development of industry and agriculture, the population is increasing. The water quality of the main stream and tributaries of Minjiang River has been polluted to some extent. Industrial wastewater and urban sewage are discharged into rivers, and the extensive use of chemical fertilizers and pesticides in agriculture aggravates this pollution. Chemical oxygen consumption, ammonia nitrogen, mercury and other water quality indicators have greatly exceeded the standard, and heavy metal mercury in Xinjin reach has exceeded the standard by five times. The chemical oxygen consumption in Leshan reach exceeded the standard 1 1 times, and the maximum value of volatile acid exceeded the standard by 32 times. The organic pollution in Yibin reach is serious. Chengdu's industrial and urban wastewater discharges 70-80 tons to Shahe, Fuhe and Nanhe rivers every day.