For improving reservoir desilting operating functions to accelerate reservoir management and the maintained reservoir operating life, so that using jet flow gate to replace existing HowellBunger valve in Tsengwen Reservoir Permanent River Outlet (T.R.P.R.O.) at southern of Taiwan. Except building three new article tunnels respectively provides construction maintenance and the ventilation needs outside, tie Jet gate room space needs, the original valve gate room will expansion upwards, and set doubletrack wire rope hoists to settlement what HowellBunger valve due to row sand wear and air volume insufficient, and the followup equipment maintenance update and transport problem. To enhance reservoir operation safety, it will priority open jet flow gate facility during typhoon and flood period, excluding density current or muddy lake high concentrations of silt and reduce siltation and improve the efficiency of reservoir desilting.