Overall Project
To mitigate floods, the government, in 1960, has started planning the overall flood control project for Taipei area; but due to the enormous budget, the government could not execute it immediately. The Taipei area flood control project uses the 200-year-flood frequency as protection criteria for its planning, and builds dikes alongside the banks of Danshuei River and its branches. The high density of houses alongside the banks of Taipei Bridge pass prevented the broadening plan , therefore, utilizing flood diversion, the Erchong Floodway was constructed to mitigate the floods of Sindian River and Dahan River.
Designed flood: Sindian River 10,300 m3/s, Dahan River 13,200 m3/s, the two merging into Danshuei River with the flood amount 23,500 m3/s. In addition, the Erchong Floodway diverts flood amount 9,200 m3/s, while Danshuei river below Kwantu was designed as 25000 cms.
Danshuei River, merging Dahan River, Sindian River and Keelung River, has a basin area of 2726 km2. Because of the unique landforms of the basin, the floods are enormous. The Taipei Bridge and Kwantu pass segments, with their narrow river channels, cause bottle-neck effect on flooding, therefore Erchong floodway was built to divert extra flood. To protect the lives and properties of the local residents, flood control projects are of urgent priority.