Yuansantze Flood Diversion Project(員山子分洪道)
Due to the 1998 Zeb typhoon and Babs typhoon flooding of 345 acres and 343 acres lands, the Executive Yuan in the 2603rd meeting appraised and appointed the WRA to execute the “Keelung River Control Construction Early Stage Plan” expecting to reach the protection criteria of 10-year return-period flood, with subsequent second stage plan to be executed. The second stage plan and the integrated overall report (draft) were proposed to the Executive Yuan in April 2000.
The results are summarized as the following:
- The initial estimated budget was 105 billion NT dollars, and the takedown of thousands of local houses is difficult to execute. Further research should be done for alternative, executable plans.
- In consideration of the budget, priority should be placed on feasibility analysis of Yuansantze Flood Diversion Project paired up with flood insurance or other alternative plans.
- The overall proposal should be further analyzed and appraised, and should be resubmitted to the Executive Yuan with the completion of practical feasible plans.
The watershed area of the Keelung River Basin is 491 km2. The drainage area of the Yuansantze Flood Diversion Tunnel approximates 90 km2. The tunnel was designed to divert flood discharge of 1,310 m3 per second, which is the peak flow of 200-year return-period flood. According to hydraulic analysis, it can lower the downstream water level about 1.5 m in average.