Introduction to ancient water conservancy projects: There was originally a culvert built in the city that connected with the outside of the city. On the walls of the east and west culverts, there are the words "Chongyong Barrier Flow" and "Jintang Consolidation" respectively engraved on them. There is a moon dam built above the culvert, which is as high as the city wall, which not only facilitates the drainage of accumulated water in the city, but also blocks external water from pouring into the city during the flood season.