Why did Minjiang River disappear in Dujiangyan, Chengdu?
Obviously, the Minjiang River system can't disappear in Chengdu, and it has also created Dujiangyan, a great irrigation project, so the Minjiang River has become the most important water resource flowing in Chengdu Plain.
Dujiangyan was built at the end of Zhao Haoqi in Qin Dynasty, which is the most famous part, including the bottle mouth, flying sand weir and water fish mouth. It has been irrigated to this day, and is called Woye Li Qian? Land of abundance? More than two thousand years. Dujiangyan irrigation, a large-scale water conservancy project, not only has an irrigation area of10 million mu, but also is Terry, which has the longest working hours and no dam for drinking water in the world. It is the best embodiment of the wisdom and hard work of the ancient people in China, and was also listed in the World Cultural Heritage List by the United Nations in 2000.
In fact, there are quite a few oolong stories related to the Minjiang River throughout the ages, including but not limited to the disappearance of the middle reaches of the Minjiang River flowing through Chengdu for no reason. For example, the ancients mistook the positive source of the Yangtze River for the Minjiang River, or regarded a river at the southern foot of Minshan Mountain in Songpan County as the positive source of the Minjiang River. But in fact, the positive source of the Yangtze River is actually the Jinsha River, and the positive source of the Minjiang River is the Dadu River in the west. The fundamental reason is that on the one hand, we don't know enough about related water systems, on the other hand, the world will be limited by our own times.
How did Minjiang River become a spider web irrigation system in Chengdu Plain?
The so-called disappearance of the Minjiang River is actually a transformation of the Minjiang River when it flows through Dujiangyan, and it has not completely disappeared on the map, but there have been some bifurcations since Dujiangyan. This is because the fish mouth of Dujiangyan divides the Minjiang River into Neijiang, Waijiang and a series of gates. The significance of building a bottle mouth is to control the water quantity in Neijiang.
Waijiang River refers to Jinma River (Zhengnan River), whose main function is flood discharge, especially in summer, which is prone to heavy rain. The total length of Jinma River is about 76. 1km, and the riverbed width is increased from 200m to 1200m. It flows through Dujiangyan City, Wenjiang District, Wuhou District, Qingyang District, Shuangliu District and chongzhou city, and finally joins Nanhe Branch and Xihe Branch in Wujin Town, Xinjin County.
Dujiangyan has several gates, namely: Puyang River, Shagou River, Baitiao River, Jiang 'an River, Heishi River and Zouma River, and a relatively small tributary, Liu Yanghe. The existence of the seven main tributaries of Minjiang River irrigates dozens of counties and cities in Chengdu Plain. Dujiangyan is not bad, is it? Irrigation? General existence, which is why today's Dujiangyan City was originally called guanxian, while the national road from Chengdu to Dujiangyan has been called? Irrigation line? .
Although a small amount of water resources will flow into the Tuojiang River after the Minjiang River is divided into several tributaries, most of the Dujiangyan water conservancy system will flow into the Fuhe River, and finally join the Jinma River in Jiangkou Town, pengshan county to form the Minjiang River again. The Minjiang River has evolved into an irrigation system like a spider's web, thus nourishing the whole Chengdu Plain. It is no exaggeration to say that the Minjiang River is like the mother river of Chengdu Plain, the so-called land of abundance, and it is inseparable from the Dujiangyan water conservancy project to make full use of the Minjiang River system.
Known as? Land of abundance? What are the characteristics of water system distribution in Chengdu Plain?
There is no doubt that the Minjiang River system is important to the Chengdu-Chongqing Plain, but there is another important water system flowing in the Chengdu-Chongqing Plain, that is, the Tuojiang River system, which is mainly composed of Yujiang River, Shi Ting River and Mianyuan River. To put it simply, Tuojiang River and Minjiang River both enter from the west side of Chengdu Plain, showing fan-shaped distributary characteristics.
In Chengdu Plain, there will be a river with an average distance of less than 2.5 kilometers, which is enough to reflect the number of rivers on the plain. The distribution of water system in Chengdu Plain is dominated by dense rivers. At present, most of these flowing rivers are improved from natural rivers. The large and small rivers distributed in Chengdu Plain are called cobwebs because they have many branches, buckets, agricultural canals and hairy canals on the basis of main canals. When we reduce the map, it looks like a dense net.
Chengdu Plain is rich in water resources and abundant in rainfall, which is one of the climatic characteristics of Chengdu Plain. We can perceive from a set of specific data that the average groundwater resources for many years can reach 4.298 billion cubic meters, the recharge of rivers, canals and irrigation can reach 3.088 billion cubic meters, and the recharge of precipitation can reach about 65.438+0.2 billion cubic meters. Therefore, even though Dujiangyan water conservancy project has played a role in diverting water to irrigate farmland, diverting floods and reducing disasters to a certain extent, it is still difficult to avoid floods in some areas of Chengdu.