旭子如风
你好In China,Chengdu is always praised as the Tian Fu Zhi Guo,which means 'Nature's Storehouse'.Over 2,200 years ago,the city was threatened by the frequent floods caused by flooding of the Minjiang River (a tributary of the Yangtze River ).Li Bing,a local official of Sichuan Province at that time,together with his son,decided to construct an irrigation system on the Minjiang River to prevent flooding.After a lengthy study and a lot of hard work by the local people,the great Dujiangyan Irrigation Project was completed.Since then,the Chengdu Plain has been free of flooding and the people have been living peacefully and affluently.Now,the project is honored as the 'Treasure of Sichuan',which still plays a crucial role in draining off floodwater,irrigating farms and providing water resources for more than 50 cities in the province.Dujiangyan is the oldest and only surviving no-dam irrigation system in the world; and a wonder in the development of Chinese science.The project consists of three important parts,namely Yuzui,Feishayan and Baopingkou scientifically designed to automatically control the water flow of the rivers from the mountains to the plains throughout the year.Yuzui,like a big fish lying in the Minjiang River,is a watershed dividing the river into two parts:inner river and outside river.Feisha Yan is a spillway that diverts the sand and stones of the inner river into the outer river.Baoping Kou,like a neck of a bottle,is used to bring water into the inner river from Minjiang.At the same time,Baoping Kou controls the amount of the intake water due to its reasonable location.These three parts interact with each other perfectly to form an effective water conservancy project.During the low-water season,60% of the Minjiang water is brought into the inner river for irrigation while 40% of the water is drawn into the outside river.The situation is reversed in the flood season ensuring the water supply for ir满意请采纳
大大大华哥呢
The Dujiangyan Dam, 45km north of Chengdu, is an ancient technological wonder of the country. More than 2000 yers ago, Li Bing(250-200BC), as a local governor of the Shu State, designed this water control and irrigation dam and organized thousands of local people to complete the project to check the Mingjiang River.For many years the river,flooded the Chengdu agricultural area and local farmers suffered a lot from the water disaster. Due to the success of the project, the dam automatically diverts the Mingjiang River and channels it into irrigation canals. For many years the dam has continued to make the most of the water conservancy works.Expansion has been undertaken since 1949 and at present the system does a good job of irrigating farming land across 33counties of the western part of Sichuan Province. Local people feel proud of the system becaude it has supported a large amount of people in their daily life.What makes this system so good?The system is a large hydraulic water project which consists of three main parts: the Fish Mouth Water-Dividing Dam, the Flying Sand Fence, and the Bottle-Neck Channel.The Fish mouth functions to divide the flow of water into an inner river and an outer river. Long ago, when Li Bing worked as the local governor of the Shu State, he found the old river canal was too narrow to hold much water, which often overflowed the banks and caused disastrous flood. Based on natural geographic conditions, he organized the people to build a man-made dam. The whole dam looks like a fish, and the front dam has a circular cone shaped like a fish mouth. It is the dam that channels water into an outer canal and an inner canal. The outer water canal functions as the main stream and holds sixty percent of water in the river. The extra water goes through the inner canal for irrigation in Chengdu areas.The Flying Sand Fence joins the inner and outer canals. The fence functions to controll the flow of water and discharge excess into the inner canal from the main stream. During the dry season the fence doesn‘t work much, but when floods occur, the river rushes forward along the outer canal. As it approaches the fence, the fence,the river begins to turn round fast and soon many whirlpools are formed. The volatile whirlpools sweep away sand and pebbles and, throw them into the outer canal. For many years huge bamboo baskets were used as the fence. They were filled with stones and pebbles. However,at present, reinforced concrete weir has replaced the ancient fence.So now, let‘s discuss the Bottle-Neck Channel. A trunk canal was cut through the mountain into two parts which link up the inner canal for irrigation. The small part is later called Li Dui, which means an isolated hill. Chengdu looks like a large bottle and the trunk canal between the mountain and the hill takes shape of the bottleneck. The trunk canal technically has two functions: First, it leads the water to irrigate the farming land in western Sichujan; Secondly, the trunk casnal works together with the Flying Sand Weir to keep the flow below a certain point in the inner canal during flood season. Some stone tablets, which stand on the isolated hill, are engraved in Buddhist Sanskrit. The local people hope that the Buddhist tablets can exert the Buddhist superpower to harness flood disaster. For over two thousand years, in fact, the Fish Mouth Water-Dividing Dam, the Flying Sand Weir, and the Bottle-neck Channel automatically work together to control foods and sweep away sand and stones in the main stram. The local people benefit a lot from this project.
