Hwacheon Dam
Encyclopedia
Hwacheon Dam is a concrete gravity dam on the North Han (Pukhan) River
Han River (Korea)
The Han River is a major river in South Korea and the fourth longest river on the Korean peninsula after the Amnok, Duman, and Nakdong rivers. It is formed by the confluence of the Namhan River , which originates in Mount Daedeok, and the Bukhan River , which originates on the slopes of Mount...

 in Hwacheon County
Hwacheon County
Hwacheon County is a county in Gangwon Province, South Korea. The northern border parallels the Korean Demilitarized Zone, as close as 9 km in some places. Neighboring counties are Cheorwon to the northwest and north, Yanggu to the east, Chuncheon to the south, and the Gyeonggi-do province to...

, Gangwon-do Province
Gangwon-do (South Korea)
Gangwon-do is a province of South Korea, with its capital at Chuncheon. Before the division of Korea in 1945, Gangwon and its North Korean neighbour Kangwŏn formed a single province.-History:...

, South Korea. The dam was completed in 1944 as a primary source of electricity in South Korea. The focal point of a raid during the Korean War
Korean War
The Korean War was a conventional war between South Korea, supported by the United Nations, and North Korea, supported by the People's Republic of China , with military material aid from the Soviet Union...

, it also provides flood protection from North Korea's Imnam Dam
Imnam Dam
Imnam Dam is a North Korean dam on the Bukhan River, completed in 2003.Construction began in 1986. The dam was immediately seen as a threat by the South Korean government. The Bukhan River is a tributary of the Han River, and war scenarios foresaw North Korea releasing flood waters that could...

.

Background

The dam was constructed by the Japanese during their occupation of Korea in World War II. The Han River Hydroelectric Company began construction in July 1939 and the dam was complete in October 1944. Several months prior in May, the first generator of the power plant was operational, second that October. The third generator was operational in 1957 and the last of the four generators was installed in 1968. Before the upstream Peace Dam
Peace Dam
The Peace Dam is a South Korean dam on the Bukhan River. It was built to stave off possible catastrophic flooding should the upstream Imnam Dam in North Korea collapse, either intentionally or by accident. The dam was completed in 2005. As it stands, the dam has no reservoir, and is merely...

 was completed in 2005, the Hwacheon Dam served as the first line-of-defense for a collapse or excess discharge from the Imnam Dam
Imnam Dam
Imnam Dam is a North Korean dam on the Bukhan River, completed in 2003.Construction began in 1986. The dam was immediately seen as a threat by the South Korean government. The Bukhan River is a tributary of the Han River, and war scenarios foresaw North Korea releasing flood waters that could...

 in North Korea.

Korean War raid

At midnight 8 April 1951, North Korea and Chinese forces released excess water from the dam's spillway
Spillway
A spillway is a structure used to provide the controlled release of flows from a dam or levee into a downstream area, typically being the river that was dammed. In the UK they may be known as overflow channels. Spillways release floods so that the water does not overtop and damage or even destroy...

 which disabled five floating bridges of the United Nations Command
United Nations Command (Korea)
The United Nations Command is the unified command structure for the multinational military forces supporting the Republic of Korea during and after the Korean War...

 downstream. The dam had been previously assessed as a problem and key facility in the area due to its hydroelectric power and ability to flood downstream areas. Capturing or disabling it became key. On 9 April, the 7th Cavalry Regiment, already executing Operation Rugged in the area, were charged with capturing the dam but were unsuccessful after encountering stiff defense. Between 16 and 21 April, Allies had secured the dam but were repelled in a Chinese counterattack before being able to destroy the dam's floodgates. After B-29s failed to neutralize the dam, on 30 April, Skyraiders fired Tiny Tim rockets
Tiny Tim (rocket)
The Tiny Tim was an American air to ground rocket used near the end of the Second World War. One source states it was built in response to a US Navy requirement for an anti-shipping rocket capable of hitting ships outside of their anti-aircraft range, with a payload capable of sinking heavy shipping...

 at and dropped a pair of 2,000-pound bombs on the dam, puncturing one spillway gate. On 1 May, Air Group 19 assaulted the dam with eight Skyraiders that were equipped with Mk 13
Mark 13 torpedo
The Bliss-Leavitt Mark 13 torpedo was the U.S. Navy's most common aerial torpedo of World War II. It was designed with unusually squat dimensions for its type: diameter was and length . In the water, the Mark 13 could reach a speed of for up to . The Mark 13 ran slower than the Mark 14 torpedo...

 torpedoes and escorted by twelve Corsairs. Seven of eight torpedoes struck the dam and six exploded. The attack alleviated the dam as a flood threat, destroying one sluice gate and damaging several others. One of the participating U.S. Navy squadrons, VFA-195
VFA-195
Strike Fighter Squadron 195 , also known as the "Dambusters", is a United States Navy F/A-18E Super Hornet fighter squadron stationed at Naval Air Facility Atsugi...

 was renamed from Tigers to Dambusters.
This raid constitutes the last time globally that an aerial torpedo
Aerial torpedo
The aerial torpedo, airborne torpedo or air-dropped torpedo is a naval weapon, the torpedo, designed to be dropped into water from an aircraft after which it propels itself to the target. First used in World War I, air-dropped torpedoes were used extensively in World War II, and remain in limited...

 was used against a surface target, and was the only time torpedoes were used in the Korean War.

Design

The dam is a 78 m (256 ft) tall and 435 m (1,427 ft) long concrete gravity-type. The dam sits at a the head of a 3901 km² (1,506 sq mi) catchment area and its reservoir has a gross capacity of 1018000000 cubic metre. Of this capacity, 809 million m3 can be regulated and 213 million m3 is used for flood control. The reservoir's surface area is 38.9 km² (15 sq mi). The dam's spillway
Spillway
A spillway is a structure used to provide the controlled release of flows from a dam or levee into a downstream area, typically being the river that was dammed. In the UK they may be known as overflow channels. Spillways release floods so that the water does not overtop and damage or even destroy...

 is controlled by 16 sluice gates and has a maximum discharge capacity of 5428 m3/s. The dam's power station is located 2.5 km (2 mi) southwest of the dam at 38°05′56"N 127°45′44"E, just over a ridge. The power station contains four 27 MW turbine
Turbine
A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and...

-generators and has an effective hydraulic head
Hydraulic head
Hydraulic head or piezometric head is a specific measurement of water pressure above a geodetic datum. It is usually measured as a water surface elevation, expressed in units of length, at the entrance of a piezometer...

of 74.5 m (244 ft).
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