Landslide dam

A landslide dam or barrier lake is a natural damming of a river by some kind of landslides, such as debris flows and rock avalanches, or by volcanic eruptions.[1] If the damming landslides are caused by an earthquake, it may also be called a quake lake. Some landslide dams are as high as the largest existing artificial dam.[2]

Causes

The major causes for landslide dams investigated by 1986 are landslides from excessive precipitation and earthquakes, which account for 84%. Volcanic eruptions account for a further 7% of dams.[3] Other causes of landslides account for the remaining 9%.

Consequences

The water impounded by a landslide dam may create a dam reservoir (lake) that may last from short times to several thousand years.[2]

Because of their rather loose nature and absence of controlled spillway, landslide dams frequently fail catastrophically and lead to downstream flooding, often with high casualties. A common failure scenario is overflowing with subsequent dam breach and erosion by the overflow stream.[2]

Landslide dams are responsible for two types of flooding: backflooding (upstream flooding) upon creation and downstream flooding upon failure. Compared with catastrophic downflooding, relative slow backflooding typically presents little life hazard, but property damage can be substantial.

Falling river level causing landslide 1
Profiles of the dam reservoir and groundwater upstream (the landslide dam is not shown in the figure)
Falling river level causing landslide 2
Groundwater after dam failure downstream

While the dam is being filled, the surrounding groundwater level rises. The dam failure may trigger further catastrophic processes. As the water level rapidly drops, the uncompensated groundwater hydraulic pressure may initiate additional landslides. Those that fall into the dam reservoir may lead to further catastrophic spillages. Moreover, the resulting flood may undercut the sides of the river valley to further produce landslides downstream.[2]

After forming, the dam leads to aggradation of the valley upstream, and dam failure leads to aggradation downstream.[2]

Construction engineers responsible for design of artificial dams and other structures in river valleys must take into account the potential of such events leading to abrupt changes in river's regimen.

Examples

References

  1. ^ "Natural Debris Dams and Debris-Dam Lakes". USGS/Cascades Volcano Observatory, Vancouver, Washington. 2003. Retrieved 2008-03-16.
  2. ^ a b c d e f Robert B. Jansen (1988) "Advanced Dam Engineering for Design, Construction, and Rehabilitation", ISBN 0-442-24397-9
  3. ^ R.B. Jansen refers to Schuster R.L. and Costa J.E., "A Perspective on Landslide Dams", in Landslide Dams by the American Society of Civil Engineers, 1986, pp. 1-20.
  4. ^ Offer, R.E. (Robert) (1997). Walls for Water: Pioneer Dam Building in New Zealand. Palmerston North: The Dunmore Press Ltd. ISBN 978-0-86469-313-6.
  5. ^ Amid race to drain Chinese quake lake, emergency plans proceed_English_Xinhua Archived 2008-05-29 at the Wayback Machine
  6. ^ Flooding spreads more destruction in town below 'quake lake' - International Herald Tribune
  7. ^ Schuster, R.L. and G. F. Wieczorek, "Landslide triggers and types" in Landslides: Proceedings of the First European Conference on Landslides 2002 A.A. Balkema Publishers. p.66
1786 Kangding-Luding earthquake

An earthquake occurred on 1 June 1786 in and around Kangding, in what is now China's Sichuan province. It had an estimated magnitude of about 7.75 and a maximum perceived intensity of X (Extreme) on the Mercalli intensity scale. The initial quake killed 435 people. After an aftershock ten days later, a further 100,000 died when a landslide dam collapsed across the Dadu river.

1933 Diexi earthquake

The 1933 Diexi earthquake occurred in Diexi, Mao County, Szechwan, Republic of China on August 25 with a moment magnitude of 7.3 and a maximum Mercalli intensity of X (Extreme). With up to 9,300 killed, this was the deadliest earthquake of 1933.

This earthquake destroyed the town of Diexi and surrounding villages, and caused many landslides, and killed about 9,000 people. The old town of Diexi sank into the landslide dam-created Diexi Lake.

Attabad Lake

Attabad Lake (Urdu: عطا آباد جھیل‎) is a lake in Gojal Valley, Hunza, Gilgit Baltistan, an administrative region of Pakistan. The lake was created in January 2010 as a result of the Attabad Disaster. Attabad Lake has become one of the biggest tourist attractions in Gilgit-Baltistan offering activities like boating, jet skiing, fishing and other recreational activities.

Diexi Lake

Diexi Lake (Chinese: 叠溪海子; pinyin: Diéxī Hǎizi) is a lake in Diexi, Mao County, Sichuan, China.

Diexi Lake is a landslide dam-created lake formed in the 1933 Diexi earthquake and covers 3.5 square kilometers. The old town of Diexi sank into this lake. The remnants of the town's watch towers, a temple, stone lions and cliff murals are still visible today.

Gros Ventre landslide

The Gros Ventre landslide ( groh-VAHNT) is in the Gros Ventre Wilderness of Bridger-Teton National Forest, Wyoming, United States. The Gros Ventre landslide is seven miles (11 km) east of Jackson Hole valley and Grand Teton National Park.

The landslide occurred on June 23, 1925, following melt from a heavy snowpack, several weeks of heavy rain, and earthquake tremors in the area. Approximately 50,000,000 cu yd (38,000,000 m3; 1.4×109 cu ft) of primarily sedimentary rock slid down the north face of Sheep Mountain, crossed over the Gros Ventre River and rode up the opposite mountainside a distance of 300 feet (91 m). The landslide created a large dam over 200 feet (61 m) high and 400 yards (370 m) wide across the Gros Ventre River, backing up the water and forming Lower Slide Lake.

On May 18, 1927, part of the landslide dam failed, resulting in a massive flood that was six feet (1.8 m) deep for at least 25 miles (40 km) downstream. The small town of Kelly, six miles (9.7 km) downstream, was wiped out, killing six people. It is one of the world's largest known examples of recent mass wasting events aside from volcanic eruptions. Slide Lake is now much smaller than before the flood.

Today, the landslide is partially reclaimed by the surrounding forest but is still an obvious landmark from many vantage points in the Jackson Hole valley. It is easily accessible by traveling north from Jackson, Wyoming or south from Moran, Wyoming and then taking the Antelope Flats road east off U.S. Route 26.

Lake Borabay

Lake Borabay, also known as Lake Kocabey, (Turkish: Borabay Gölü or Kocabey Gölü) is a landslide-dammed lake in Amasya Province, Turkey. The lake and its surroundings were declared a nature park in 2014.

The lake is in Taşova ilçe (district) of Amasya Province It is situated to the west of the town Borabay. Its distance to Taşova is 21 km (13 mi) and to Amasya is 61 km (38 mi).The lake is situated in the 1,051 m (3,448 ft)-high, east-west-oriented valley on the Black Sea Mountains. It was formed when the river was blocked by a landslide. The landslide dam was strengthened later with a concrete weir to avoid its split off by flooding. It is 675 m (2,215 ft) long and has a maximum width of 175 m (574 ft). Its total area is around 4 ha (9.9 acres). Its maximum depth is 11 m (36 ft).The lake freezes in the winter time.

Lake Christabel

Lake Christabel is a small lake in the north of New Zealand's South Island. It is located 12 kilometres southwest of the Lewis Pass. The lake is the source of the Grey River, one of the longest rivers on the South Island's West Coast, although its outlet is underground. The lake lies behind a landslide dam, thought to have been created by a prehistoric earthquake.

Mount Meager (British Columbia)

Not to be confused with the Mount Meager massif, which is also commonly referred to as Mount Meager.Mount Meager is a mountain in the Pacific Ranges of the Coast Mountains in British Columbia, Canada. It represents the second highest peak of the Mount Meager massif, a group of coalescent stratovolcanoes in the Garibaldi Volcanic Belt.The mountain was the source of the 2010 Mount Meager landslide. On August 6, the southern 2,554 m (8,379 ft) peak of Meager collapsed in a series of major rockfalls. The rockfalls transformed into a large debris flow that dammed Meager Creek for about one day. The landslide dam was about 30 m (98 ft) high and impounded water in a temporary lake about 4 km (2.5 mi) long. The debris flow also crossed the Lillooet River downstream and wiped out a forestry road on the opposite bank of the Lillooet River. The response of emergency personnel, fearing a sudden failure of the dam on Meager Creek, was to direct residents on the Lillooet River floodplain, in the village of Pemberton 55 km (34 mi) downstream and in the Lil'wat community at Mount Currie to evacuate the area.

Mount Tangjia

Mount Tangjia (Chinese: 唐家山; pinyin: Tángjiā Shān) is a mountain in Sichuan Province, China, 3.2 kilometres away from the county seat of Beichuan County.It overlooks the Jian River and Tangjiashan Lake, a landslide dam-created lake which was formed by the 2008 Sichuan earthquake.

Phoksundo Lake

Phoksundo Lake, (Nepali: फोक्सुण्डो ताल, NLK Phoksuṇḍo tāl), is an alpine fresh water oligotrophic lake in Nepal's Shey Phoksundo National Park, located at an elevation of 3,611.5 m (11,849 ft) above sea level in the Dolpa District. Phoksundo Lake is 494 ha (1.91 sq mi) in size with a water volume of 409,000,000 m3 (1.44×1010 cu ft) and a discharge of 3.715 m3/s (131.2 cu ft/s). In 2004, a survey by the Department of Hydrology and Meteorology measured the maximum depth of the lake at 145 m (476 ft).In September 2007, Phoksundo Lake has been designated a Ramsar site.On the lake' southern end, the village of Ringmo sits on the 30,000- to 40,000-year-old landslide dam that formed the lake. Past the dam, the waters of the lake plunge over a 167 m (548 ft) tall waterfall.

Poerua River

Poerua River is the name of two rivers in the West Coast region of New Zealand's South Island.

The northern Poerua River flows from Lake Poerua into the Crooked River, which leads to Lake Brunner.

The southern Poerua River flows from its headwaters in the Southern Alps to the Tasman Sea near Harihari. The river is a trout and salmon fishing location and its mouth is where it is met by the Hinatua River and is located roughly a kilometre south of the Wanganui River's mouth. On the morning of 6 October 1999, a landslide from Mount Adams blocked the Poerua River, creating a landslide dam about 11 km upstream from the State Highway 6 bridge over the river. Despite fears of flooding and other damage, there were relatively minimal impacts when the dam was breached six days later, though significant quantities of coarse gravel were deposited downstream and the river's course was changed in places.

Ringmo

Ringmo is a traditional village in Dolpo in the Dolpa District of Nepal, with a seasonal population of about 200. The people are mostly of Tibetan ethnicity, are of the Bönpo faith, and engage in trade, yak herding and tourism. It sits on the landslide dam that formed Phoksundo Lake at about 3660 m (12,000 ft) above sea level. A Bön temple also named Ringmo can be found just outside the town, and the river that drains from Phoksundo plunges over an impressive 167 m (548 ft) waterfall about half a kilometer south of the village.Ringmo is the seat of the Phoksundo village development committee.

Rivière de Grand Goâve

The Rivière de Grand Goâve is a river of Haiti.

The 12 January 2010 7.0 tremor created a landslide which formed a landslide dam blocking the river, that can potentially contain a large basin of water. Though it is now dry, the wet season is approaching, and a dam collapse would directly outflow the contents through the city of Grand-Goâve. The dam is located a dozen kilometres from the city of Grand-Goâve.

Sarez Lake

Sarez Lake is a lake in Rushon District of Gorno-Badakhshan province, Tajikistan. Length about 75.8 kilometres (47.1 mi), depth few hundred meters, water surface elevation about 3,263 metres (10,705 ft) above sea level and volume of water is more than 16 cubic kilometres (3.8 cu mi). The mountains around rise more than 2,300 metres (7,500 ft) above the lake level.

The lake formed in 1911, after a great earthquake, when the Murghab River was blocked by a big landslide. Scientists believe that the landslide dam formed by the earthquake, known as the Usoi Dam, is unstable given local seismicity, and that the terrain below the lake is in danger of catastrophic flood if the dam were to fail during a future earthquake.Shadau Lake is a small water body southwest of the Usoi Dam and west of Sarez Lake.

Siaolin Village

Siaolin Village (Chinese: 小林里; Hanyu Pinyin: Xiǎolín; Tongyong Pinyin: Siǎolín; Wade–Giles: Hsiao-Lin), also spelled Xiaolin Village, is a village in Jiasian District, Kaohsiung, Taiwan. It is mostly agricultural and home to one of the largest communities of the Taivoan people.

In 2009, Typhoon Morakot brought unprecedented rainfall to southern Taiwan, including Siaolin. A landslide dam upstream of Siaolin failed catastrophically, resulting in a devastating mudflow to completely cover the northern half of the village. 471 people lost their lives in the incident.

Spanish Fork River

The Spanish Fork (often referred to as the Spanish Fork River) is a river in southeastern Utah County, Utah, United States.

Tangjiashan Lake

Tangjiashan Lake (Chinese: 唐家山堰塞湖, literally "Tang's Mountain landslide dam-created lake") is a landslide dam-created lake on the Jian River, which was formed by the 2008 Sichuan earthquake. Its name comes from the nearby mountain Tangjiashan. On May 24, 2008 the water level rose by 2 metres (6 ft 7 in) in a single day, reaching a depth of 23 metres (75 ft), just 29 metres (95 ft) below the barrier level. On June 9 2008, more than 250,000 people have been evacuated from Mianyang in anticipation of the Tangjiashan Lake dam bursting.A similar lake in the same province that formed 222 years earlier caused one of the worst landslide-related disasters in history. On June 10, 1786 a landslide dam on Sichuan's Dadu River, created by an earthquake ten days earlier, burst and caused a flood that extended 1400 km downstream and killed 100,000 people.A "relatively strong" aftershock on June 8, 2008 shook the massive earthquake-formed lake that has been threatening to flood more than 1 million people and triggered landslides in surrounding mountains. Soldiers used digging equipment, explosives, and even missiles to blast channels in the dam in an attempt to relieve the pressure behind it.The flow from the sluice channel cut into the dam increased dramatically on June 10, 2008, going from 300 cubic metres/second to 7000 cubic metres/second in the span of four hours. The muddy waters flowed rapidly downstream causing flooding in the evacuated town of Beichuan and overtopping of dams.In 2013 broken banks from a severe flood caused the lake's water to fall to 503 metres above sea level, 40 metres below its peak and 9 metres below its 2010 level. As water receded, the Xuanping town in the Beichuan Qiang Autonomous County was revealed.

The lake is now within the Beichuan Earthquake Museum. Landsat imagery from 2018 showed that the lake's size was greatly reduced do to natural erosion of the barrier and filling of the lake with sediment.

Tsarap River

The Tsarap River or the Tsarap Chu (Urdu: صراف ندی‎), is a river 182 kilometres (113 mi) long, which forms the eastern part of the Zanskar valley, in the Ladakh region of the Indian state of Jammu and Kashmir.

Usoi Dam

The Usoi Dam is a natural landslide dam along the Murghab River in Tajikistan. At 567 metres (1,860 ft) high, it is the tallest dam in the world, either natural or man-made. The dam was created on February 18, 1911, when the 7.4-Ms Sarez earthquake caused a massive landslide that blocked the flow of the river.The dam is formed of approximately 2 cubic kilometres (0.48 cu mi) of rock dislodged from the steeply sloped river valley of the Murghab, which cuts from east to west through the high and rough Pamir Mountains. It is named after the village of Usoi, which was completely buried by the 1911 landslide. The dam rises to a height of 500 to 700 metres (1,600 to 2,300 ft) from the original valley floor.The basin formed by Usoi Dam now holds Sarez Lake, a 55.8-kilometre (34.7 mi)-long lake holding 16.074 cubic kilometres (13,031,000 acre⋅ft) of water. Water does not flow over the top of the dam, which would quickly cause it to erode away; instead, water seeps out of the base of the dam at a rate which approximately matches the rate of inflow, maintaining the lake at a relatively constant level. The flow averages about 45 cubic meters per second, and dissipates about 250 megawatts.

Geologists are concerned that the Usoi Dam may become unstable during future large-magnitude earthquakes, which are relatively common in the seismically active Pamirs, and might collapse due to liquefaction or subsequent landslides during such an event. Collapse of the dam would unleash a locally catastrophic flood. The Murghab's river valley tends to be relatively narrow and steep. This would focus and maintain any flood's destructive power as it swept through the valley of the Murghob District.

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