Ancient drainage system: Qin sewers were pentagonal in shape and Northern Song Dynasty zoning drainage

Water accumulation in cities is bound to seriously affect residents 'lives. Recently, affected by typhoons, heavy rains have hit the skies in Hangzhou City and Yuyao City, Zhejiang Province, and varying degrees of waterlogging and stagnant water have occurred in each Urban area...

In the Qin Dynasty, sewer pipes were pentagonal

In ancient China, urban construction planning attached great importance to the prevention and control of stagnant water. "Kao Gong Ji" in the Spring and Autumn Period: "Dou, he values three feet." "Dou" is one of the names of ancient sewers. It is also called ditch, ditch, stone canal, brick plaster, etc. There are also a variety of materials and methods used, including pottery pipes for laying, stones for building, or bricks for building.

The sewer pipe of the Qin Dynasty unearthed from Shaanxi is made of pottery and has a pentagonal shape. The pipe is 68 cm long, 46 cm high, 43 cm wide, and the pipe wall is 7 cm thick. Making the sewer into a pentagonal shape can withstand the gravity of the road surface better than a square one. It shows that the working people at that time already understood some mechanical principles. It can be seen from calculations that compared with a square water pipe of the same size, the force borne by a water pipe with a diamond shape is approximately 5:3. This design improvement greatly improves the mechanical strength.

Brick drainage ditches appeared in Tang Dynasty

The Sui and Tang dynasties had developed economies, and urban construction was more progressive than previous generations. The entire Chang 'an City is not only spacious streets, but also neatly planted trees on both sides. Drainage ditches are generally built on both sides of the streets.

Judging from the excavated drainage ditch on Zhuque Street, the ditch is 3.3 meters wide and 2.3 meters deep. Archaeologists also found brick drainage ditches under the laneway in the east and west cities. These ditches eventually led to open ditches on both sides of the street. Judging from the Tang Dynasty drainage ditch discovered in Yangzhou, it is deeply buried about 4.5 meters below the ground, and the exposed part is about 35 meters long from east to west. The ditch mouth is about 2 meters wide, the bottom is 1.75 meters wide, and the depth is 1.5 meters. It is basically excavated on the sand layer formed by the impact of the Yangtze River. After the ditch is dug, fir boards are used on both sides as the revetment, and the outside of the boards are fixed with pine wooden piles. There are three types of wooden piles: round piles, semi-round piles, and square piles, which vary according to the material. One end of the wooden piles is cut into a pointed shape., so that it can be driven into the ground.

The Northern Song Dynasty adopted zoning drainage

During the Xining period of the Northern Song Dynasty, Liu Yi became the governor of Ganzhou, Jiangxi Province, and planned and built streets in the Urban area of Ganzhou. At the same time, according to the street layout and terrain characteristics, and adopting the principle of zoning drainage, two drainage trunk systems have been built. Because the direction of the two ditches is similar to the words "Fu" and "Shou" in the seal style, it is named Fushougou. The entire system is divided into two major parts: Fugou and Shougou. The main ditch has a total length of 12.6 kilometers and a total of 6 water outlets, 3 of which discharge into the Zhangjiang River and 3 into the Gongjiang River. According to the terrain of Ganzhou City, Liu Yi used a combination of open ditches and undercanals to collude with ponds in the Urban area, and then discharged wastewater into the Zhangjiang River and Gongjiang River respectively through the 12 water windows under the city wall. This drainage system formed a drainage network in ancient Ganzhou City with "side branches and horizontal connections","vertical and horizontal winding, and clear lines", with clear primary and secondary lines, and combined drainage and storage. It played an important role in improving environmental sanitation and living conditions in the Urban area. This system also forms a large-capacity reservoir in the drainage network to regulate heavy rain flow and reduce sewer overflows. Sewage can also be used to raise fish and grow vegetables in ordinary times. Fushou Gully still plays a role in Ganzhou's urban drainage, benefiting future generations.

The sewers in the Ming and Qing Dynasties were named "Sanitation Project"

The design of Beijing, the capital city of the Ming and Qing Dynasties, mainly based on the urban planning of Chang 'an in the Tang Dynasty. According to the records of Qing Zhailian's "Shao Ting Miscellaneous Records", sewer projects in the Ming court were even stronger, either cast of raw copper or built of huge rocks, with diameters as thick as several feet. This was also a rare sanitary project worldwide at that time. After the founding of New China, we investigated ancient sewers in Beijing and found that most of the sewers built in the Ming Dynasty five to six hundred years ago were made of masonry. According to estimates by engineers and technicians, these sewers will be no problem even if they are used for another few decades.

Focus on supporting drainage planning

In addition to sewers, our country also paid great attention to supporting drainage planning in ancient times. For example, Chang 'an in the Tang Dynasty and Beijing in the Ming and Qing Dynasties emphasized urban greening. These lush trees take root in deep soil and can divert accumulated water after rain in time. Archaeology in Yangzhou also found a water culvert. It is located in the southwest of Tangluo City. The building scale and form are similar to a small city gate. It is in the form of a long tunnel with a round roof. It is 1.8 meters wide, 2.2 meters high, and 12 meters long. It is bigger than today's Yangzhou. For the drainage planning of Ganzhou, Jiangxi Province, Liu Yi's original design concept, Fushou Gully is only one part of the entire Ganzhou drainage and flood control system. The strong city wall built in the Song Dynasty is the best flood control dam, as well as hundreds of ponds in the city. Liu Yi once sent people to connect Fushou Gully with the ponds in the city to play an important role in regulation and storage. Pond increases the rainwater regulation capacity of the city during heavy rains, thereby reducing the area and time that streets are submerged.

In ancient times, to prevent and control stagnant water, we had a long-term vision and took into account the century-old foundation; on the other hand, we paid attention to utilizing the natural environment and taking advantage of the situation. In recent years, large-scale and long-term water accumulation has occurred in various places from time to time. Can our urban planning learn from ancient times?