# Ertan Dam

The Ertan Dam (simplified Chinese: 二滩大坝; traditional Chinese: 二灘大壩; pinyin: Èrtān Dàbà) is an arch dam on the Yalong River, a tributary of the Yangtze River in Sichuan Province, in southwest China.
The dam has six hydroelectric generators, each with a generating capacity of 550 MW. The total generating capacity of the facility is 3,300 MW, one of the largest hydroelectric stations in China. The annual production is 17 TWh, and until December 5, 2006, it has produced over 100 TWh of electricity. Construction of the dam started in September 1991 and was completed on December 26, 1999. A total of 12,638,000 m$^3$ (446,306,758 cu ft) of material was excavated during construction.
The Ertan Dam was designed by the China Hydropower Engineering Consulting Group Survey and Design Institute in Chengdu, and was constructed and is currently operated by Ertan Hydropower Development Company Limited, the owners of the dam. The company is invested by State Development and Investment Company (52% share) and Sichuan Chuantou Energy Limited (48% share).

## Design

The Ertan Dam is a 240 m (787 ft) high and 774.7 m (2,542 ft) long double-curvature arch dam. The dam withholds a normal reservoir of 5,800,000,000 m$^3$ (4,702,137 acre⋅ft) with a drainage area of 116,400 km$^2$ (44,942 sq mi) and normal surface area of 101 km$^2$ (39 sq mi). The dam has four different ways to discharge water downstream. First, the dam's spillways which contain seven floodgates at the crest and two flood tunnels can discharge 6,260 m$^3$/s (221,070 cu ft/s) and 7,400 m$^3$/s (261,329 cu ft/s) respectively. The dam also contains 6 x middle outlets and four bottom outlets that can discharge 6,930 m$^3$/s (244,731 cu ft/s) and 2,084 m$^3$/s (73,596 cu ft/s) respectively. The dam's power station is located underground along with its transformer room which is in a separate cavern. Additionally, the power station is supported by an underground surge chamber as well.

## Main Features

Source:
| Project Location | On the Yalong River, Sichuan province, P. R. China |
| Project Purpose | Hydroelectric Power Generation |
| Years of Construction | 1987-1999 |
| Construction of Main Dam | |
| Type | Double-curvature Arch Dam |
| Height | 240 m |
| Crest Length | 774.69 m |
| Construction of Power plant | |
| Maximum gross head | 189 m |
| Installed Capacity | 6×550 MW (Francis) |
| Power Conduits | 6 steel embedded in concrete I.D.=9.0 m |
| Catchment and Reservoir | |
| Catchment Area | 116,400 km$^2$ |
| Mean Annual Runoff | 1,670 m$^3$/s |
| Reservoir Area at FSL | 101 km$^2$ |
| Storage at FSL | 5,800 million m$^3$ |
| Active Storage | 3,370 million m$^3$ |
| Discharge Capacity | |
| Crest Outlet | 7 / 6,260 m$^3$/s |
| Mid Level Outlet | 6 / 6,930 m$^3$/s |
| Bottom Outlet | 4 / 2,084 m$^3$/s |
| Flood Discharging | 2 / 7,400 m$^3$/s |
| Project Developers | |
| Owner | Ertan Hydropower Development Company, Ltd. |
| Designer | CHIDI, now POWERCHINA Chengdu |
| Contractor | EJV, SGEJV, GYBD |
| Main Equipment Suppliers | |
| Turbines | GE Canada, Dongfang Electrical Machinery Co, Ltd., Harbin Electric Machinery Co, Ltd. |
| Generators & HV Electrical | GE Canada, Dongfang Electrical Machinery Co, Ltd., Harbin Electric Machinery Co, Ltd. |
| Gates & Hydromechanical | Jiajiang Hydraulic Machinery Works, China Gezhouba (Group) Corporation, Sinohydro Bureau No.8, |