subdrainage

例句：

1. 1. The engineer designed a system to improve the underground water flow.
   工程师设计了一个系统来改善地下水流。
2. 2.Subsurface drainage is crucial for maintaining soil health and preventing erosion.
   次级排水系统对于保持土壤健康和防止侵蚀至关重要。
3. 3.The construction of this subdrainage network will significantly reduce flooding risks in the city.
   这个次级排水网络的建设将显著降低城市洪水风险。