The poem describing the canal is as follows:
"Seven Jue Grand Canal" shows that the ice and snow of the Red Bean River connect the north and south of the country. The water rippled for thousands of years in the Sui Dynasty, sending a message to the geese flying south and returning to the north. The great river The head and tail are Jiachuan.
Canals
Canals refer to artificially dug navigable rivers. There are many definitions of canals. According to the commonly used formulation: in a narrow sense, a canal is an artificially dug navigable river. Broadly speaking, a canal is an artificial waterway used to communicate water transportation between regions or waters, and is usually connected to natural waterways or other canals. In addition to shipping, canals can also be used for irrigation, flood diversion, drainage, water supply, etc.
China has a long history of canal construction. The Xuhe River was excavated in 506 BC. It is the oldest artificial canal in the world, the earliest canal recorded in China, and the earliest canal excavated in the world. In the twenty-eighth year of Qin Shihuang (219 BC), the Ling Canal was excavated to connect shipping between the Xiangjiang River and the Lijiang River. Built primarily during the Sui Dynasty of China, the Beijing-Hangzhou Grand Canal is the longest canal in the world.
The world’s major canals include the Suez Canal, Panama Canal, Kiel Canal, Corinth Canal, Beijing-Hangzhou Grand Canal, etc.
Definition
Waterways are divided into three types: natural rivers, channelized rivers and artificial canals, each with its own special problems. Natural rivers are often frozen due to floods and droughts, forcing seasonal suspension of navigation, and even causing the river to change its course and form a sandbar. Waterway projects must focus on strengthening the riverbed and banks and maintaining the original river course. The only way to do this is to eliminate tributaries, unify the river cross-section, cut bends and straighten them, and smooth the flow of water.
On channelized rivers, cascade ship locks can be built for navigation. Where ships pass through the locks, low dams and gates can be set up to discharge excess water. When artificial canals pass through mountains and cross rivers and valleys, the banks and river beds of the canals must have protective facilities to prevent erosion and leakage.
Choose the artificial canal route to create conditions for long-distance horizontal river sections that can be quickly navigated. The ship lock construction can use stepped multi-stage ship locks, or use ladders with a short section of river between the two locks. Segmented ship lock.
The construction of the reservoir should have a high-water level reservoir that supplies water to high places to make up for the loss of water release and evaporation through the lock; a low-water level reservoir must also be built to accommodate the water released when ships frequently pass through the lock. The amount of water entered. There are more than 520 canals in the world, distributed in 52 countries, with nearly 3,000 cities along them.