The No. 4 Middle Drainage is a tributary of the Shuiyuandi drainage system and serves as an agricultural drainage channel. The original structure of the channel was composed primarily of earthen ditches, which hindered agricultural operations. The project was designed using a masonry revetment approach, taking ecological needs into account, to improve the drainage efficiency of the channel.

1. Drainage Channel Improvement (approximately 475 meters): The channel was improved using a combination of masonry revetments and reinforced concrete channels. A sloped design was adopted to facilitate wildlife movement, with masonry revetments increasing surface roughness and porosity. The slope was primarily set at 1:0.5, while in sections with sufficient space, a 1:1 slope was used.
2. New Flood Control Road (approximately 273 meters): A new flood control road was constructed for public access and leisure.
3. Greening Area (approximately 475 m²): Landscaping was installed around the No. 4 Intermediate Drainage to improve the local environment.