China is a big agricultural country, but also a big country with water shortage, and the distribution of water resources is extremely uneven, the south is rich in water resources, and the north is scarce, so how to better use water resources to serve agriculture is a problem that people have been studying. Thankfully, our ancestors built 2 great water conservancy projects for us as early as a few years ago, benefiting hundreds of people and still playing a role today. The two projects are Dujiangyan in the south and Qanerjing in the north.
First: Dujiangyan. First, let's talk about the reasons for the construction of Dujiangyan. In the late Warring States period, in order to unify the world, the Qin state stepped up the pace of destroying the Six Kingdoms. Among the six kingdoms, the strength of the State of Chu was the strongest, and the General sima of the State of Qin mistakenly believed that if he wanted to take the State of Chu, he must take the land of Bashu. When the State of Qin destroyed Bashu, in 280 BC, it sent troops to attack the State of Chu. Sima Cuo, the commander of the Qin army, led 100,000 troops down the Min River into the Yangtze River and began a war against Chu, but the outcome of the war ended in failure. The reasons are mainly in the following aspects.
1. The Qin army did not have enough grain and grass. The Chengdu Plain is flat and is the only large-yielding region in the land of Bashu, but it is drought-stricken and water-scarce all year round, so there is a shortage of food.
2. There is a lack of waterways from Chengdu to the Minjiang River. The Qin army's weapons, soldiers, grain and grass were all built and assembled in Chengdu, and then transported to the Minjiang Wharf, and then entered the Yangtze River. From Chengdu to minjiang wharf lack of waterways, it takes time and energy to take time and energy by land, and the timeliness cannot keep up.
Against this backdrop, it is important to build a river from Chengdu to the Minjiang wharf. King Zhaoxiang of Qin chose a person, and he was Li Bing. The State of Qin appointed Li Bing as the shou of Shu Commandery and was responsible for building this important river as the lifeblood of the Qin army. After Li Bing arrived, he and his son came to the minjiang river and recruited a large number of local people with experience in water management to discuss how to build this water conservancy project. Li Bing first let people in Yulei Mountain, which lasted 8 years, and he chiseled a large mouth on the Jade Lei Mountain full of stones, and named this big mouth "Treasure Bottle Mouth". After that, there were supporting projects such as Fish Mouth, King Kong Causeway, And Flying Sand Weir.
The completion of Dujiangyan not only solved the drought problem of the Chengdu Plain, but also played a huge role in flood control and transportation. The Dujiangyan water conservancy project covers more than 30 counties, and there are tens of millions of acres of farmland that can be irrigated, benefiting the people for thousands of years and nurturing countless people. The Dujiangyan Water Conservancy Project, in ancient times, was definitely a super project.
Second: the karez. Qaner wells, in layman's terms, are underground drain irrigation systems. China's Xinjiang climate is arid, everywhere is the boundless Gobi Desert, long sunshine hours, large evaporation, extreme lack of water resources. The water in Xinjiang mainly comes from the melting water of the snow-capped mountains, and how to effectively use this precious water to irrigate crops has become an important problem for people to study, so the karez came into being. Qan'erjing was first built during the reign of Emperor Xuan of Han and has a history of 2,000 years.
The karez mainly consists of 4 parts, namely a shaft, a reservoir, an underground culvert, and an open channel. The karez can make perfect use of the terrain and slope, and without wasting power, it can divert the groundwater that seeps into the ground after the snow-capped mountains melt.
According to statistics, at present, in Xinjiang, there are more than 1,200 karez wells in the Turpan Basin alone, and the total length of underground culverts is more than 5,000 kilometers, which has made great contributions to the agricultural development of the Turpan Basin. Qanerjing can be described as the crystallization of the wisdom of the working people of ancient China, and in that era when only manpower could be used, digging more than 5,000 kilometers of small tunnels underground was definitely a great feat.