Xi An, the decline of the ancient capital: 13 generations of water resourcesThe factor

Xi has special significance in the history of the East AsianEmpire. Because it was the first capital to be called "Beijing",it became the central starting point for the two modes of rule of Zhou andQin. The city-centered Guanzhong area was also where the dynasty wasestablished.

Therefore, the decline of Xi after the late Tang Dynasty has also become thesubject of many studies. In general, the main reasons summarized includethe damage caused by frequent war-torn cities and the cavitation effect causedby the southward shift of the ancient economic center of gravity. Ofcourse, this also includes the excessive expansion effect of empire capital.

Xi's waterways and ancient city walls

have received little attention in the most direct factors. This is thewater pollution factor that directly caused the decline of Xi and itssurrounding areas. Because compared to issues such as industrialadjustment and war trauma, water pollution is a very deadly problem that isdifficult to resolve quickly.

Because ancient ancestors used to get water easily, they often chose to live onwater. Designers and planners also use water as a necessary considerationwhen choosing a city location. Ordinary cities are usually built on oneside of the river, while megacities usually span both sides of the river.

Since ancient times, there have been eight major rivers near Xi.

In ancient times, there were eight rivers around, such as Wei, Jing, Feng, Lao,Luo, Hu, Hui and Ba. Therefore, it is often said that "the eightrivers flow around Chang'an." Therefore, it is not only necessary tobuild a city here, but also necessary peripheral facilities for many largecities. For example, agriculture that supports large populations is bestsuited close to the city itself. Not only is it easy to obtain and savetransportation costs, but the city garrison can protect its own farmland.

However, water can also overturn a ship. Xi's eventual decline was alsodue to overexploited water systems, which affected the city's own groundwaterquality. As early as the end of the Northern Dynasty, Emperor Sui Wenusurped the throne and found that the surrounding environment of the oldChang'an City was very bad. Several large-scale expansions since the Qinand Han Dynasties have led to the accumulation of domestic garbage in differentperiods. This situation occurred in the Han Dynasty, but was ignoredbecause the Eastern Han Dynasty moved the capital to Luoyang.

Since ancient times, Xi should not be a place where water is scarce.

After experiencing the turmoil of the Wei, Jin, and Northern and SouthernDynasties, the Yang family discovered how terrible this situation was when theywere preparing to rebuild the great empire. Due to the large amount ofpollution, the groundwater obtained by urban residents through drilling hasdeteriorated and cannot be drunk at all. This forced Sui Wendi to decideto build a new city in Longshou, southeast of the ancient city. The medievalXi, later named Daxing, became the last witness of Guanzhong's glorioushistory.

Of course, changing places doesn't mean solving the problem. Groundwaterpollution only occurred in urban areas during the Tang Zhongzong period, whichis more serious than in the past. This is because the groundwater systemsin a certain area are often interconnected, taking the sewage to a wider areaby the way. The city size of Xi in the Tang Dynasty reached its historicalpeak, as far as pollution emissions are concerned, there is nolatter. Until the establishment of the Northern Song Dynasty, more thanhalf of the well water in the city could only drink salt water.

All Xi