Reservoirs storing large volumes of water have the capability of causing considerable damage and loss of life if they fail. Reservoirs are considered "installations containing dangerous forces" under international humanitarian law because of their potential adverse impact. In 1975 the failure of the Banqiao Reservoir Dam and other dams in Henan Province, China caused more casualties than any other dam failures in history. The disaster killed an estimated 171,000 people [1] and 11 million people lost their homes.
Because reservoirs and their containing dams present such significant potential risks many countries have put legislation in place and set safety standards, but it was not until 1930 that effective legislation was first approved for control of the design, construction and maintenance of dams and reservoirs when the Reservoirs (Safety provisions) Act, 1930 was enacted in the United Kingdom.
Although failure is often portrayed as a catastrophic failure of the dam wall to contain the mass of water held up behind the dam, there a number of significant other causes of failure. These include:
Not all countries have specific legislative control over the safety of dams and reservoirs, and a number of those that do have legislation have it at State or province level only. Some such as the US have both Federal and State legislation. In some, such as Australia legislation is at State level but only some states have relevant legislation.
Australia issued "Guidelines on Dam Safety Management in 1994" but specific safety legislation is enacted at State level. New South Wales, Queensland and Victoria have all enacted legislation. [2] In Queensland a concept of a "referable dam" is used to determine whether the legislation applies. A referable dam is defined by a number of criteria including a height exceeding 8 metres (26 ft) and a volume of 500 cubic metres (110×10 3 imp gal) . A number of other conditions and caveats apply. [2] In New South Wales the Dams Safety Act establishes an expert committee to oversee surveillance of "prescribed" dams. The list of prescribed dams is not based on height or volumes but is a list contained in a schedule to the Act. [2]
The government of New Zealand is consulting the public about the proposal to establish legislative control over the design, construction and monitoring of dams and reservoirs. [3] The consultation include proposed definitions of "classifiable" dams which would be either "at or above 4 metres in height and 20,000 cubic metres in volume; or less than 4 metres in height, but at or above 30,000 cubic metres in volume". The document acknowledges the special issues facing New Zealand because of the frequency of potentially damaging earthquakes. [3]
In Britain, the demand for water for the many industries that flourished in the Industrial Revolution and the need for drinking water for the thousands of workers who had migrated from the countryside to the cities for work, put great strains on the water supply infrastructure and led to the construction of many reservoirs in the hillier parts of the country, especially in the Pennines and mid and north Wales. In the absence of any legislation or control of quality or design it was inevitable that failures would occur and by 1863 at least 12 dams had failed causing loss of life. [4]
In 1864 a newly constructed dam at Dale Dyke near Sheffield failed as the reservoir was being filled and the resultant out-wash killed 244 people. [4] As a result, a draft bill requiring dams and reservoirs to have their plans and the construction approved by an independent competent person was written in 1865 but was lost when there was change of government. [4]
Reservoirs (Safety Provisions) Act 1930 | |
---|---|
Act of Parliament | |
Long title | An Act to impose, in the interests of safety, precautions to be observed in the construction, alteration, and use of reservoirs, and to amend the law with respect to liability for damage and injury caused by the escape of water from reservoirs. |
Citation | 20 & 21 Geo. 5. c. 51 |
Dates | |
Royal assent | 1 August 1930 |
Other legislation | |
Repealed by | Reservoirs Act 1975 |
Status: Repealed |
This Act entered the statute book following the coupled failure of two reservoirs in North Wales. Llyn Eigiau and the Coedty Reservoir were two relatively small reservoirs. On a wet November night, Eigiau failed and the out-wash overwhelmed Coedty 2.5 miles downstream. Sixteen villagers in Dolgarrog were killed.
The new Act applied to reservoirs holding more than 5 million imp gal (0.023 million m3) and mandated that construction had to be supervised by a qualified engineer and the filling of the reservoir also had to be supervised and certified. It also set out for the first time an inspection requirement that every qualifying reservoir had to be inspected every ten years by an engineer included on a published list or panel of engineers. These panels were compiled by the relevant Secretary of State in liaison with the president of the Institution of Civil Engineers. [4] Since the Act came into force no lives have been lost in any reservoir or dam failure in the UK.
Reservoirs Act 1975 | |
---|---|
Act of Parliament | |
Long title | An Act to make further provision against escapes of water from large reservoirs or from lakes or lochs artificially created or enlarged. |
Citation | 1975 c. 23 |
Dates | |
Royal assent | 8 May 1975 |
Other legislation | |
Repeals/revokes | Reservoirs (Safety Provisions) Act 1930 |
Status: Current legislation | |
Text of statute as originally enacted | |
Text of the Reservoirs Act 1975 as in force today (including any amendments) within the United Kingdom, from legislation.gov.uk. |
Despite the success of the 1930 act, further legislation was brought onto the statute books in 1975. The new legislation recognised that more significant people were involved in the design and construction of a dam and the impoundment and it assigned accountabilities to those identified players. It also raised the volume threshold to 25 thousand m3 (5.5 million imp gal) and "provides the legal framework within which qualified civil engineers make technical decisions." [4]
It also introduced the roles of supervising engineer and enforcement authority – a role assigned to the appropriate local authority. However, implementation of the Act took from 10 to 12 years so it was not fully implemented until 1987. [4] In 2004 the role of enforcement authority in England and Wales was reassigned to the Environment Agency.
A series of severe dam failures in the 1970s prompted Congress to take action. These failures included Buffalo Creek, West Virginia which failed, devastating a 16-mile valley and killing 125 people. [5] As a result, Congress enacted Public Law 92–367 in November 1977 which authorized the U.S. Army Corps of Engineers to inventory and inspect non-Federal dams. [6]
The Water Resources Act 1986 established a National Dam Safety Review Board although there was not a National Dam Safety Program until 1986. [6] The legislation authorising this program was last amended by The Dam Safety Act of 2006.
Although some 79 people were killed by dam failures in 1979 at the Laurel Run Dam and at the Kelly Barnes Dam, it is likely that only a single death in the US has been caused by subsequent failures which was below the failed Spencer Dam. [7]
The legislation varies on a country by county basis across Europe. Italy and Spain both have a minimum reservoir capacity of 1,000 million m3 (220,000 million imp gal). France sets a minimum height of 20 metres (66 ft) while Spain and Portugal and Austria all set a minimum height of 15 metres (49 ft) but each with different volume minima. [8]
Dartmouth Dam is a large rock-fill embankment dam with an uncontrolled chute spillway across the Mitta Mitta, Gibbo and Dart rivers, the Morass Creek and a number of small tributaries. The dam is located near Mount Bogong in the north-east of the Australian state of Victoria. The dam's purpose includes irrigation, the generation of hydro-electric power, water supply and conservation. The impounded reservoir is called Dartmouth Reservoir, sometimes called Lake Dartmouth. The Dartmouth Power Station, a hydro-electric power station that generates power to the national grid, is located near the dam wall.
The Teton Dam was an earthen dam in the western United States, on the Teton River in eastern Idaho. It was built by the U.S. Bureau of Reclamation, one of eight federal agencies authorized to construct dams. Located between Fremont and Madison counties, it suffered a catastrophic failure on June 5, 1976, as it was filling for the first time.
Lake Burragorang is a man-made reservoir in the lower Blue Mountains of New South Wales, Australia, serving as a major water supply for greater metropolitan Sydney. The dam impounding the lake, the Warragamba Dam, is located approximately 60 kilometres (37 mi) southwest of the Sydney central business district.
Oroville Dam is an earthfill embankment dam on the Feather River east of the city of Oroville, California, in the Sierra Nevada foothills east of the Sacramento Valley. At 770 feet (235 m) high, it is the tallest dam in the U.S. and serves mainly for water supply, hydroelectricity generation, and flood control. The dam impounds Lake Oroville, the second-largest reservoir in California, capable of storing more than 3.5 million acre-feet (1.1×10 12 US gal; 4.3×109 m3).
Frankley Reservoir is a semi-circular reservoir for drinking water in Birmingham, England, operated by Severn Trent Water. Its construction was authorised by the Birmingham Corporation Water Act 1892 It was built by Birmingham Corporation Water Department to designs by Abram Kellett of Ealing in 1904.
Googong Dam is a minor ungated earth and rock fill with clay core embankment dam with concrete chute spillway plus a nearby 13 metres (43 ft) high earthfill saddle embankment across the Queanbeyan River upstream of Queanbeyan in the Capital Country region of New South Wales, Australia. The dam's purpose includes water supply for Canberra and Queanbeyan. The impounded reservoir is called Googong Reservoir.
The Clywedog Reservoir is a reservoir near Llanidloes, Wales on the head-waters of the River Severn. The construction of the reservoir was enabled by an act of Parliament, the Clywedog Reservoir Joint Authority Act 1963, which asserted that "At certain times the flow of water in the river is inadequate ... unless that flow were regulated so as to ensure that at those times water in addition to the natural flow will flow down the river."
Llyn Cowlyd is the deepest lake in northern Wales. It lies in the Snowdonia National Park at the upper end of Cwm Cowlyd on the south-eastern edge of the Carneddau range of mountains, at a height of 330 metres (1,083 ft) above sea level. The lake is long and narrow, measuring nearly 3 kilometres (2 mi) long and about 500 m wide, and covers an area of 1.1 square kilometres. It has a mean depth of 33 metres (108 ft) and at its deepest has given soundings of 70 metres (230 ft), this being some 14 m (46 ft) greater than its natural depth, the water surface having been raised twice by the building of dams.
Dolgarrog is a village and community in Conwy County Borough, in Wales, situated between Llanrwst and Conwy, very close to the Conwy River. The village is well known for its industrial history since the 18th century and the Eigiau dam disaster, which occurred in 1925. The population was 414 at the 2001 Census, increasing to 446 at the 2011 Census. The community extends up to, and includes part of, Llyn Cowlyd in the Carneddau.
The Queen Mary Reservoir is one of the largest of London's reservoirs supplying fresh water to London and parts of surrounding counties, and is located in the Borough of Spelthorne in Surrey. The reservoir covers 707 acres (2.86 km2) and is 45 ft (14 m) above the surrounding area.
The Cowlyd Tramway was a 2 ft narrow gauge railway line used to convey men and materials to Llyn Cowlyd Reservoir, near Trefriw in northern Wales during the enlargement of the dam, and thereafter for maintenance purposes.
Scofield Reservoir is a 2,815-acre (11.39 km2) reservoir impounded by Scofield Dam, in Carbon County, Utah. Located on the Price River, a tributary of the Green River, Scofield Reservoir is adjacent to the northernmost boundary of the Manti–La Sal National Forest. The reservoir sits at an elevation of 7,618 feet (2,322 m), on the northern edge of the Wasatch Plateau. Utah State Route 96 runs along the western shoreline.
Glen Canyon Dam, a concrete arch dam on the Colorado River in the American state of Arizona, is viewed as carrying a large amount of risk, most notably due to siltation. The Colorado and San Juan rivers deposit large volumes of silt into Lake Powell, slowly decreasing its capacity. The sediment will eventually build up against the dam and could affect its safe operation and lead to its failure.
The Cotter Dam is a concrete gravity and rockfill embankment dam across the Cotter River, located in the Australian Capital Territory, Australia. Both the dam and river are named after early settler in the area Garrett Cotter. The impounded Cotter Reservoir is a supply source of potable water for the city of Canberra and its environs.
The Laurel Run Dam, also known as Laurel Run Dam No. 2, was an earthen embankment dam that failed during the Johnstown Flood of 1977. It had the largest reservoir of seven dams to fail between July 19 and 20, 1977 and caused the most fatalities of the two that did. The dam failed in the early morning of July 20 after period of heavy rain, causing 101 million US gallons (380,000 m3) of water to flood downstream Tanneryville, killing 40 people.
The Sweetwater Dam is a dam across the Sweetwater River in San Diego County, California. It is located approximately 12 miles (19 km) east of San Diego, 9 miles (14 km) and borders Bonita to the southwest and La Presa to the northeast. The 108-foot (33 m)-high masonry arch dam impounds 960-acre (390 ha) Sweetwater Reservoir.
Amistad Dam is a major embankment dam across the Rio Grande between Texas, United States, and Coahuila, Mexico. Built to provide irrigation water storage, flood control, and hydropower generation, it is the largest dam along the international boundary reach of the Rio Grande. The dam is over 6 miles (9.7 km) long, lies mostly on the Mexican side of the border, and forms Amistad Reservoir. It supplies water for irrigation in the Rio Grande Valley, 574 miles (924 km) upstream of the Rio Grande's mouth on the Gulf of Mexico at Brownsville, Texas/Matamoros, Tamaulipas.
The Manly Dam is a heritage-listed dam near King Street, Manly Vale with a reservoir extending into Allambie Heights, both in the Northern Beaches Council local government area of New South Wales, Australia. It is often used as a place to have recreational activities. The reservoir is located within the Manly Dam Reserve. The dam was designed by the NSW Department of Public Works and built in 1892 by the Department. The reservoir and dam is owned by Sydney Water, an agency of the Government of New South Wales. The reservoir and dam was added to the New South Wales State Heritage Register on 18 November 1999.
Morena Dam is a rockfill dam across Cottonwood Creek, a tributary of the Tijuana River in southern San Diego County, California. Originally completed in 1912 and raised several times afterward, the dam is one of the oldest components of the city of San Diego's municipal water system, providing between 1,600 to 15,000 acre-feet of water per year. It is one of the few facilities in the San Diego water supply system that relies entirely on local runoff.
There are a large number of reservoirs in Wales reflecting the need for the supply of water for both industry and for consumption, both within the country itself and in neighbouring England. A number also provide hydroelectricity and many old reservoirs also provided motive power for industries, especially for the processing of minerals such as metal ores and slate.
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