Fushou Ditch is an underground drainage system built in Song Dynasty in China, and it is one of the most outstanding drainage systems in the early world. Located underground of zhanggong district Old Town, Ganzhou City, Jiangxi Province. It is a large-scale ancient masonry drainage system under the ancient city of Ganzhou.

The water window (sluice) in Fushou Ditch is located on the side near the river, and it is opened and closed to the outside world, mainly because it is "knocked open" when the urban displacement is large, and the excess water in the city is discharged into the river, that is, the opening and closing frequency of the water window is high in rainy season.

Ganzhou, located in the south of Jiangxi, belongs to the subtropical monsoon climate zone. In summer, it is hot and rainy, rivers are well supplied, and Fushou Ditch has a large amount of water. Therefore, the month when the water window is frequently opened and closed is July, which is in the rainy summer.