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Zengwen Reservoir

Summary
Work Content:
I、Reservoir
Catchment Area 481 km²
Water Storage Area 19 km²
Water Storage Elevation 230 m
Effective Capacity 510,020,000 m³

II、Main Structures
Main Dam
Type A rolled earth fill dam of center impermeable core  type
Dam Top Elevation 236m
Dam Height 134m
Dam Length 400m
Embankment Volume 9,300,000 m³

III、Spillway:
Type Floodgate-controlled3-phase energy-reducing flip bucket open ditch
Floodgate Three arched steel gates: height of 20.5m x width: 15m
Spillway Elevation 211 m
Weir Height 12m
Crest Length 446m
Max. Flow Rate 11345m³/sec

IV、River Tunnel Water Discharge Area
Type Inclined Water Fetch Tower + tunnel
Inlet Central Elevation 155.0 m
Outlet Central Elevation 115.76m
Raft and Vertical Sliding Gate 2 sets, each measuring 1.95 m in diameter
Tunnel(ID) 3.9 m in internal diameter; 210 m in length
Max. Water Discharge 180 m³/sec

V、Power Plant Water Fetch Area (Shares Water Tower With River Tunnel Water Discharge Area)
Type Inclined water fetch tower + tunnel
Min. Power Generation Water Level 171m
Fetch Area Central Elevation 165m
Tunnel(ID) 3.8m in internal diameter; 289m in length
Weishui Tunnel 140 m (length)
Fetch Capacity 56 m³/sec

VI、Zengwen Reservoir Sediment-Sluice Tunnel
Type emergency gate + contral gate + tunnel
Inlet Central Elevation 175m
Plunge pool Elevation 94m
Tunnel(ID) 9 m in internal diameter; 1267 m in length
Max. Water Discharge 1070 m³/sec when the water level of the reservoir is 235m
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 Office 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