Toker Dam is the fourth largest dam in Eritrea. Construction was begun in 1997 and completed in 2001, despite having to be halted for a few months in 1998 when Ethiopia and Eritrea were at war. Its primary designer was Natural Resources Consulting Engineers from Colorado, USA. Furthermore, NRCE Inc., was the primary consultant on the project. The construction contractor was Keagnam of South Korea.
Eritrea, officially the State of Eritrea, is a country in the Horn of Africa, with its capital at Asmara. It is bordered by Sudan in the west, Ethiopia in the south, and Djibouti in the southeast. The northeastern and eastern parts of Eritrea have an extensive coastline along the Red Sea. The nation has a total area of approximately 117,600 km2 (45,406 sq mi), and includes the Dahlak Archipelago and several of the Hanish Islands. The name Eritrea is based on the Greek name for the Red Sea, which was first adopted for Italian Eritrea in 1890.
The project was designed to provide modern and effective service to the City of Asmara and neighboring villages. It further provides safe drinking water for the local population. The dam is a roller compacted concrete dam, and was one of the highest in sub-Saharan Africa at the time it was built.
Asmara or Asmera is the capital and most populous city of Eritrea, in the country's Central Region. It sits at an elevation of 2,325 metres (7,628 ft), making it the sixth highest capital in the world by altitude. The city is located at the tip of an escarpment that is both the northwestern edge of the Eritrean Highlands and the Great Rift Valley in neighbouring Ethiopia. In 2017, the city was declared as a UNESCO World Heritage Site for its well-preserved modernist architecture. Asmara was first settled in 800 BC with a population ranging from 100 to 1000. The city was then founded in the 12th century AD after four separate villages unified to live together peacefully after long periods of conflict.
The dam is 73 metres tall and is composed of 210,000 cubic metres (7,400,000 cu ft) of concrete. The upstream face is vertical and the downstream face is sloping, with a central spillway. The reservoir can hold 17,000,000 cubic metres (600,000,000 cu ft) of water; there is a pumping station at its toe, leading to a water filtration plant. This has a capacity of 20,000 cubic metres (710,000 cu ft) water per day which is delivered to the city of Asmara's distribution system.
During construction, the cofferdam was overtopped for about four days during a large flood, when the dam was about one third of its final height. The flood was in excess of the once in a hundred years flood expectation. The contractors had little warning but managed to get most of their equipment away from the critical area before the event struck. The conventional and roller-compacted concrete in the main dam were largely undamaged and construction work was resumed within a fortnight.
A cofferdam is an enclosure built within, or in pairs across, a body of water to allow the enclosed area to be pumped out. This pumping creates a dry work environment so that the work can be carried out safely. Enclosed coffers are commonly used for construction or repair of permanent dams, oil platforms, bridge piers, etc ., built within or over water.
Roller-compacted concrete (RCC) or rolled concrete (rollcrete) is a special blend of concrete that has essentially the same ingredients as conventional concrete but in different ratios, and increasingly with partial substitution of fly ash for Portland cement. The partial substitution of fly ash for Portland Cement is an important aspect of RCC dam construction because the heat generated by fly ash hydration is significantly less than the heat generated by Portland Cement hydration. This in turn reduces the thermal loads on the dam and reduces the potential for thermal cracking to occur. RCC is a mix of cement/fly ash, water, sand, aggregate and common additives, but contains much less water. The produced mix is drier and essentially has no slump. RCC is placed in a manner similar to paving; the material is delivered by dump trucks or conveyors, spread by small bulldozers or specially modified asphalt pavers, and then compacted by vibratory rollers.
Kárahnjúkar Hydropower Plant, officially called Fljótsdalur Power Station is a hydroelectric power plant in Fljótsdalshérað municipality in eastern Iceland, designed to produce 4,600 gigawatt-hours (17,000 TJ) annually for Alcoa's Fjarðaál aluminum smelter 75 kilometres (47 mi) to the east in Reyðarfjörður. With the installed capacity of 690 megawatts (930,000 hp), the plant is the largest power plant in Iceland. The project, named after the nearby Kárahnjúkar mountains, involves damming the rivers Jökulsá á Dal and Jökulsá í Fljótsdal with five dams, creating three reservoirs. Water from the reservoirs is diverted through 73 kilometres (45 mi) of underground water tunnels and down a 420-metre (1,380 ft) vertical penstock towards a single underground power station. The smelter became fully operational in 2008 and the hydropower project was completed in 2009.
Mangrove Creek Dam, a concrete faced concrete faced rockfill embankment dam, is the primary reservoir for water supply to residents of the Central Coast in New South Wales, Australia.
Pangue Hydroelectric Plant is a hydroelectric power station in Bío Bío Region, Chile. It lies west of Callaqui volcano at the confluence of the rivers Pangue and Huiri-Huiri. The plant uses water from the upper Bío Bío River and produces 467 megawatts (626,000 hp) of electricity. The plant was built by Endesa in 1996.
The Wyaralong Dam is a mass concrete gravity dam with an un-gated spillway across the Teviot Brook that is located in the South East region of Queensland, Australia. The main purpose of the dam is for supply of potable water for the Scenic Rim region. The impounded reservoir is also called Wyaralong Dam. The dam was initiated by the Queensland Government in 2006 as a result of a prolonged drought which saw the catchment areas of South East Queensland's dams receive record low rain.
The Miyagase Dam is a dam on the Nakatsu River, a main tributary of the Sagami River in Aikō District, Kanagawa Prefecture, Japan. It straddles the border between the village of Kiyokawa, town of Aikawa and the former town of Tsukui.
Willow Creek Dam is a dam in Morrow County of the U.S. state of Oregon, located just east of Heppner's city limits. It was the first major dam in the United States constructed of roller-compacted concrete.
The Cotter Dam is a concrete gravity and rockfill embankment dam across the Cotter River, located in the Australian Capital Territory, Australia. The impounded reservoir is called the Cotter Reservoir which is a supply source of potable water for the city of Canberra and its environs.
The Yeywa Hydropower Station, located on the Myitnge River, 52 kilometres (32 mi) southeast of Mandalay city, at Yeywa village in Kyaukse Township, Mandalay Region in central Myanmar, is the country's first roller-compacted concrete (RCC) dam, and the site of a 790-megawatt (1,060,000 hp) hydroelectric power plant, the largest in the country.
The Governor José Richa Hydroelectric Plant, formerly known as Salto Caxias, is a dam and hydroelectric power plant on the Iguazu River near Caxias in Paraná, Brazil. It is the first dam upstream of the Iguazu Falls and was constructed between 1995 and 1999. The power station has a 1,240-megawatt (1,660,000 hp) capacity and is supplied with water by a roller-compacted concrete gravity dam.
The São Simão Dam is an embankment dam on the Paranaíba River near São Simão in Goiás/Minas Gerais, Brazil. It was constructed for hydroelectric power production and flood control. The dam was completed in 1978 and all generators were operational by 1979. In 1977, the first use of roller compacted concrete in Brazilian dam construction occurred on the São Simão.
The Guangzhao Dam is a concrete gravity dam on the Beipan River near Guangzhao in Guanling County, Guizhou Province, China. The main purpose of the project is hydroelectric power generation with additional purposes of water regulation and irrigation. It creates the uppermost or head reservoir on the Beipan and was constructed between 2003 and 2008.
The El Quimbo Dam is a concrete faced rock-fill dam (CFRD) and hydroelectric power project under development in the Huila Department of southwestern-central Colombia, approximately 69 kilometres (43 mi) south of the city of Neiva, on the Magdalena River. It is located about 1,300 metres (4,300 ft) upstream from the confluence of the Páez River with the Magdalena River. Its works were officially opened on February 25, 2011 in the presence of President Juan Manuel Santos. It is one of the largest infrastructure projects in the country. The project is planned to be completed over a period of 4 years, in 2015.
The Miel I Dam, officially known as the Patángoras Dam, is a gravity dam on La Miel River just south of Norcasia in Caldas Department, Colombia. The dam was constructed between 1997 and 2002 for the primary purpose of hydroelectric power generation. At the time of its completion, the dam was the tallest roller-compacted concrete (RCC) dam in the world but was surpassed by the Longtan Dam in 2009.
The Jiangya Dam is a concrete gravity dam on the Loushui River, located 50 km (31 mi) northeast of Zhangjiajie in Hunan Province, China. The primary purpose of the multi-purpose dam is flood control but it also generates hydroelectricty, supplies water for irrigation and municipal use and improves navigation.
Big Tujunga Dam is a 244-foot (74 m)-high concrete arch dam in Los Angeles County, California, spanning Big Tujunga Canyon northeast of Sunland, in the foothills of the San Gabriel Mountains. Completed in 1931, it provides flood control and groundwater recharge for the San Fernando Valley.
The Daguangba Dam is a multi-purpose dam on the Changhua River in Hainan Province, China. It is located 35 km (22 mi) east of Dongfang. As the primary component of the Daguangba Multipurpose Project, the dam was constructed between 1990 and 1995. It serves to provide water for both hydroelectric power generation and agriculture. It supports a 240 MW power station and supplies water for the irrigation of 12,700 ha. It is also the largest dam and hydroelectric power station in Hainan.
The Hohhot Pumped Storage Power Station, also known by Huhehaote, is located 20 kilometres (12 mi) north of Hohhot in Inner Mongolia, China. It uses the pumped-storage hydroelectric method to generate electricity. The plant has an installed capacity of 1,224 megawatts (1,641,000 hp). Construction began in 2005 and the first generator was commissioned on 20 November 2014. The second generator was commissioned on 26 December 2014 and the final two were commissioned in June 2015.
The Ntimbale Dam is a dam on the Tati River in Botswana. It has a capacity of 26,000,000 cubic metres (920,000,000 cu ft).
The Dikgatlhong Dam is a dam near the village of Robelela on the Shashe River in Botswana, completed in December 2011. When full it will hold 400,000,000 cubic metres (1.4×1010 cu ft). The next largest dam in Botswana, the Gaborone Dam, has capacity of 141,000,000 cubic metres (5.0×109 cu ft).
The Hantangang Dam is a gravity dam currently under construction on the Hantan River in Yeoncheon County, Gyeonggi Province, South Korea. Construction on the dam began in 2007 and it is expected to be completed in mid-2015. The primary purpose of the dam will be flood control and it was proposed in 1998 after a series of deadly floods in the late 1990s. These floods killed 128 people, displaced over 31,000 and caused about US$900 million in property damage. Initially designed as a multi-purpose project, the design was changed solely to flood control in 2006 due to the concerns of residents upstream. It is being implemented by Korea Water Resources Corporation (K-water).