Why has the 600-year-old Forbidden City in Beijing never had water accumulation? In fact, the Forbidden City contains the wisdom of the ancients, in addition to using the height of the terrain, but also with a sophisticated drainage system, so that such a large Forbidden City encounters heavy rain, can quickly discharge rainwater, like the black technology drainage system, so that modern people also look very admirable.
In order not to prevent the flooding problem of the Forbidden City in Beijing, the ancients designed a sophisticated drainage system, so that the ground displacement is greater than the precipitation, when the public stands in the square in front of the Taihe Hall, you can find that the three halls of the Taihe Hall, the Zhonghe Hall, and the Bohol Hall are located on the jade base, and the jade base is about 7 meters high and divided into three layers, and each layer is surrounded by carvings of dragon heads.
Whenever it rains heavily, the dragon head carving will spew out water, the cornice flowing water is like a waterfall, and the dragon head has a total of 1142, these are actually the so-called drainage holes, the ancients not only understand drainage, but also attach great importance to beauty, so the drainage hole is designed as a faucet, drainage will form a "dragon spit water" beauty, the picture is very spectacular, these rainwaters then flow into the Forbidden City Taihe gate in front of the east-west flow of the "NeijinShui River".
Not only that, the ancients also set up 3 defensive lines outside the Forbidden City, the first is the "Ming Inner City Moat, Daming Hao and Taiping Lake", the second is "Xiyuan Tailiu Pond and Houhai", and the last is "Waijinshui River and the Tube River of the Forbidden City", which is the so-called moat, these canals are usually used to provide urban water supply, but when encountering heavy rain, there is a drainage effect, so that there will not be a large amount of rainwater and torrents flowing into the palace outside the Forbidden City.
And the rainwater in the Forbidden City will eventually pass through the drainage channels of the trunk and branch lines, flow into the Neijinshui River, and then flow out along the canal to the south of the Donghua Gate, and merge with the Waijinshui River, in addition, the ancients not only have a sophisticated drainage system, but also according to the topography of the Forbidden City, because Beijing is north of Yanshan Mountain, east of the Bohai Sea, it can be known that Beijing's terrain is northwest high, southeast low, so Beijing's water system is southeast, the ancients took advantage of this feature, the forbidden city water system designed as north high south low.
In addition, the drainage system is based on the emperor's middle royal road as the watershed, the terrain on the east and west sides of the watershed line is gradually reduced, and when it rains, the rainwater will flow into the moat along the terrain to the east and west sides, but although the Forbidden City has the problem of river canals and terrain flood prevention, but the palace buildings are many and dense, each courtyard blocks each other, which will also lead to poor drainage system effect, so the ancients are more precise in the drainage design of the courtyard, setting up open ditches, dark ditches, culverts, flowing ditches, etc., so that each ditch is crisscrossed, forming a huge and complete drainage network.
The drainage system is divided into drainage ditches and underground channels, when the open channel water encounters steps or walls, the ancients will open holes at the bottom, that is, the so-called "ditch eyes", so that rainwater flows from the ground into the mouth of the culvert, and the mouth of the culvert is designed into the shape of the carved Ming and Qing copper coins, also known as "money eyes", the ancients designed a precision drainage system, coupled with regular maintenance by modern people, so that the Forbidden City has not flooded for 600 years.