Summary
Work Content：
I、Reservoir
| Catchment Area | 481 km² |
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| Water Storage Area | 19 km² |
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| Water Storage Elevation | 229 m |
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| Effective Capacity | 48,654,000 m³ |
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II、Main Structures
Main Dam| Type | A rolled earth fill dam of center impermeable core type |
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| Dam Top Elevation | 236m |
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| Dam Height | 134m |
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| Dam Length | 400m |
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| Embankment Volume | 9,300,000 m³ |
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III、Spillway：
| Type | Floodgate-controlled3-phase energy-reducing flip bucket open ditch |
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| Floodgate | Three arched steel gates: height of 20.5m x width: 15m |
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| Spillway Elevation | 211 m |
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| Weir Height | 12m |
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| Crest Length | 446m |
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| Max. Flow Rate | 11345m³/sec |
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IV、River Tunnel Water Discharge Area
| Type | Inclined Water Fetch Tower + tunnel |
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| Inlet Central Elevation | 155.0 m |
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| Outlet Central Elevation | 115.76m |
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| Raft and Vertical Sliding Gate | 2 sets, each measuring 1.95 m in diameter |
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| Tunnel(ID) | 3.9 m in internal diameter; 210 m in length |
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| Max. Water Discharge | 180 m³/sec |
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V、Power Plant Water Fetch Area (Shares Water Tower With River Tunnel Water Discharge Area)
| Type | Inclined water fetch tower + tunnel |
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| Min. Power Generation Water Level | 171m |
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| Fetch Area Central Elevation | 165m |
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| Tunnel(ID) | 3.8m in internal diameter; 289m in length |
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| Weishui Tunnel | 140 m (length) |
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| Fetch Capacity | 56 m³/sec |
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VI、Zengwen Reservoir Sediment-Sluice Tunnel
| Type | emergency gate + contral gate + tunnel |
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| Inlet Central Elevation | 175m |
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| Plunge pool Elevation | 94m |
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| Tunnel(ID) | 9 m in internal diameter; 1267 m in length |
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| Max. Water Discharge | 1070 m³/sec when the water level of the reservoir is 235m |
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| 995m³/sec when the water level of the reservoir is 230m |
Zengwen Reservoir is situated upstream of Zengwen Creek with 7 hundred million stere gross capacity and 17 myriari lake area.Both are the largest in Taiwan. The main dam is made up of embankment measuring 133 m, which ranks after the second highest dam in Taiwan, Techi Reservoir. The dam volume exceeds 9 million stere, which is the largest in Taiwan. The Transbasin spillway is divided into three parts. Different from other reservoirs that have only single chutes, its discharge elevation operates in coordination with flood discharge volume selected at inlet control gate to perform the max. energy removal functions.
Not alike single tunnel as usual did, it was designed two 12 m diversion tunnels during the construction period. Zengwen Reservoir's main functions are power generation and flood preventation. It works associated with WushanTou Reservoir which conduct water supply and irrigation.Due to population growth and economic developments of the southern region, the water supply which originally plays a minor role in Zengwen Reservoir function has become increasingly important. Due to hydraulic limitations, although the reservoir capacity is large enough, the time in full storage is scarce showing there is still room for improvement. Thus, Water Resources Branch has proposed Zengwen Channeling Project to direct tributaries of Gao-ping such as Lao-Nong River or Chi-Shan River into the reservoir through channeling.
Functional Efficacy
1.Irrigation：area 66.680hectares(passing through Wushantou Reservoir )
2.Water Supply：350,000 m3/day (passing through Wushantou Reservoir)
3.Power Generation：Annual power generation: .212,000,000 watt (Zengwen Power Generation Plant)
4.Flood Mitigation
5.Tourism