noun
riparian works; river engineering works
Technical term for construction, improvement, or maintenance works on rivers and waterways, such as embankments, dredging, and flood control.
この地域では河川工事が行われている。
River engineering works are being carried out in this area.
治水工事 focuses specifically on flood control and water management, while 河川工事 is a broader term covering all types of river construction and maintenance.
Compound of 河川 (river) and 工事 (construction works).