“Washing the beach deeply, building weirs low” is a famous saying in Dujiangyan water control. Beach washing means that a section of the Feishayan and a section of the Neijiang River must be dug deeply. The standard for deep washing is that the ancients prepared deep water at the bottom of the river. Buried "lying iron". The beach should be built as far as the horizontal iron to ensure the water supply in the irrigation area is just right. A low weir means that the Feisha Weir has a certain height. If it is higher, more water will enter, and if it is lower, less water will enter, which is not appropriate. In ancient times, Feisha Weir was a temporary project built with bamboo cages and pebbles; now it is cast in concrete to ensure a permanent effect. Baopingkou is a hole cut in the long ridge of Qianshan (now known as Guankou Mountain and Yulei Mountain) extending to the Minjiang River. It is an artificially cut throat to control the inflow of water from the Inner River. Because it resembles the mouth of a bottle, it has a unique function. Hold, hence the name Baopingkou. The hill left on the right side of Baopingkou is named Lidui because it is separated from the mountain. The width and bottom height of Baoping are strictly controlled. The ancients carved dozens of divisions on the rock wall and named them "Shui Rules". They were the earliest water level scales in my country. Yuzui, Feishayan, Baoping Pingkou, the three major main projects at the head of Dujiangyan Canal, may seem ordinary and simple to ordinary people, but they do not know that it contains extremely huge scientific value. It contains systems engineering, fluid mechanics, etc., today It is still at the forefront of contemporary science and technology and is generally promoted and used. However, these scientific principles have been applied in practice as early as 2,000 years ago in the Dujiangyan Water Conservancy Project. This is a symbol of ancient Chinese civilization and the pride of our descendants of Yan and Huang.

Dujiangyan has a long history and benefits future generations. Its secret is not only the ingenious engineering layout, but more importantly, it follows the guiding ideology of water control of "taking advantage of the situation and adapting to the current conditions" and the principle of "repairing every year" The management system, the river management principle of "cut corners when encountering difficulties, and draw back the heart when times are right", as well as the management experience and weir management principles of "building fish mouths to fill gaps, deep shoals, and low weirs" for water diversion, sand control, and flood discharge . The essence of the guiding ideology of "taking advantage of the situation and adapting to current conditions" is a water management philosophy that is applicable everywhere. It emphasizes the need to fully grasp the flow of rivers and other natural conditions, and use and guide them correctly to utilize them. Favorable conditions eliminate unfavorable factors. At the same time, they should change with time, location and specific conditions, and take different measures to complete the project. This philosophy of water control has very important reference and guiding significance not only for the past, but also for our water conservancy work today.

The eight-character motto here is "cut corners when encountering bays, draw attention when encountering good times", which is a method for regulating the Minjiang River, solving water transportation problems in irrigation areas, and dredging flood drainage rivers. It can also be said to be the method for regulating and dredging rivers. general rules. "Meeting the bay and cutting corners" refers to cutting off sharp angles on the convex bank when repairing the river, reducing the buffering force and making it straighter, so as to reduce the erosion of the river bank by the mainstream. When there are many forks in a river section or river course, the middle part of the river bed should be dug deeper to achieve the purpose of concentrating the main stream, so that the river water can flow "smoothly and smoothly" to avoid flooding and destroying banks and farmland.