A dam is a barrier that stops or restricts the flow of water or underground streams. Reservoirs created by dams not only suppress floods but provide water for activities such as irrigation, human consumption, industrial use and navigability. Hydropower is used in conjunction with dams to generate electricity. A dam can be used to collect water or for storage of water which can be evenly distributed between locations. Dams serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions; the earliest known dam is the Jawa Dam in Jordan, dating to 3,000 BC. The word dam can be traced back to Middle English, before that, from Middle Dutch, as seen in the names of many old cities; the first known appearance of dam occurs in 1165. However, there is one village, mentioned in 1120; the word seems to be related to the Greek word taphos, meaning "grave" or "grave hill". So the word should be understood as "dike from dug out earth".

The names of more than 40 places from the Middle Dutch era such as Amsterdam and Rotterdam bear testimony to the use of the word in Middle Dutch at that time. Early dam building took place in the Middle East. Dams were used to control the water level, for Mesopotamia's weather affected the Tigris and Euphrates rivers; the earliest known dam is the Jawa Dam in Jordan, 100 kilometres northeast of the capital Amman. This gravity dam featured an 9-metre-high and 1 m-wide stone wall, supported by a 50 m-wide earth rampart; the structure is dated to 3000 BC. The Ancient Egyptian Sadd-el-Kafara Dam at Wadi Al-Garawi, located about 25 km south of Cairo, was 102 m long at its base and 87 m wide; the structure was built around 2800 or 2600 BC as a diversion dam for flood control, but was destroyed by heavy rain during construction or shortly afterwards. During the Twelfth Dynasty in the 19th century BC, the Pharaohs Senosert III, Amenemhat III and Amenemhat IV dug a canal 16 km long linking the Fayum Depression to the Nile in Middle Egypt.

Two dams called Ha-Uar running east–west were built to retain water during the annual flood and release it to surrounding lands. The lake called "Mer-wer" or Lake Moeris is known today as Birket Qarun. By the mid-late third millennium BC, an intricate water-management system within Dholavira in modern-day India was built; the system included 16 reservoirs and various channels for collecting water and storing it. One of the engineering wonders of the ancient world was the Great Dam of Marib in Yemen. Initiated somewhere between 1750 and 1700 BC, it was made of packed earth – triangular in cross section, 580 m in length and 4 m high – running between two groups of rocks on either side, to which it was linked by substantial stonework. Repairs were carried out during various periods, most important around 750 BC, 250 years the dam height was increased to 7 m. After the end of the Kingdom of Saba, the dam fell under the control of the Ḥimyarites who undertook further improvements, creating a structure 14 m high, with five spillway channels, two masonry-reinforced sluices, a settling pond, a 1,000 m canal to a distribution tank.

These extensive works were not finalized until 325 AD and allowed the irrigation of 25,000 acres. Eflatun Pınar is a Hittite spring temple near Konya, Turkey, it is thought to be from the time of the Hittite empire between the 15th and 13th century BC. The Kallanai is constructed of unhewn stone, over 300 m long, 4.5 m high and 20 m wide, across the main stream of the Kaveri river in Tamil Nadu, South India. The basic structure dates to the 2nd century AD and is considered one of the oldest water-diversion or water-regulator structures in the world, still in use; the purpose of the dam was to divert the waters of the Kaveri across the fertile delta region for irrigation via canals. Du Jiang Yan is the oldest surviving irrigation system in China that included a dam that directed waterflow, it was finished in 251 BC. A large earthen dam, made by Sunshu Ao, the prime minister of Chu, flooded a valley in modern-day northern Anhui province that created an enormous irrigation reservoir, a reservoir, still present today.

Roman dam construction was characterized by "the Romans' ability to plan and organize engineering construction on a grand scale." Roman planners introduced the then-novel concept of large reservoir dams which could secure a permanent water supply for urban settlements over the dry season. Their pioneering use of water-proof hydraulic mortar and Roman concrete allowed for much larger dam structures than built, such as the Lake Homs Dam the largest water barrier to that date, the Harbaqa Dam, both in Roman Syria; the highest Roman dam was the Subiaco Dam near Rome. Roman engineers made routine use of ancient standard designs like embankment dams and masonry gravity dams. Apart from that, they displayed a high degree of inventiveness, introducing most of the other basic dam designs, unknown until then; these include arch-gravity dams, arch dams, buttress dams and multiple arch buttress dams, all of which were known and employed by the 2nd century AD. Roman workforces were the first to build dam bridges, such as the Bridge of Valerian in Iran

Ōhāriu spelled Ohariu and Ōhariu, is a New Zealand parliamentary electorate returning one Member of Parliament to the House of Representatives. It first existed from 1978 to 1993, was recreated for the 2008 election. In 2008, it was the successor to Ohariu-Belmont, first contested at the first mixed-member proportional election in 1996. Through its existence Ohariu-Belmont was represented by Peter Dunne, leader of the United Future party. Dunne contested and won the recreated electorate in 2008, he announced on 21 August 2017, he would not be seeking re-election in the 2017 general election. The 1977 electoral redistribution was the most overtly political since the Representation Commission had been established through an amendment to the Representation Act in 1886, initiated by Muldoon's National Government; as part of the 1976 census, a large number of people failed to fill in an electoral re-registration card, census staff had not been given the authority to insist on the card being completed.

This had little practical effect for people on the general roll, but it transferred Māori to the general roll if the card was not handed in. Together with a northward shift of New Zealand's population, this resulted in five new electorates having to be created in the upper part of the North Island; the electoral redistribution was disruptive, 22 electorates were abolished, while 27 electorates were newly created or re-established. These changes came into effect for the 1978 election; the Ohariu electorate replaced the Karori electorate, but did not include any of Khandallah or Ngaio. In 2008, the boundaries of the Ohariu-Belmont and Ōhariu electorates were near identical except for the removal of the eponymous Lower Hutt suburb of Belmont into the Rimutaka electorate and the addition of Crofton Downs from Wellington Central; the new electorate contained the section of Wellington City between Crofton Downs and southern Tawa, including Ngaio, Khandallah and Newlands. The rest of the electorate consisted of Lower Hutt's hill suburbs of Korokoro and Normandale.

Ōhariu was one of eleven electorate names to include a macron, for the first time. The name was changed to include a second macron. Both Ohariu-Belmont and Ōhāriu are wealthy. 69 % of its population is 14 % Asian and 8 % Māori. Despite Dunne having a 7,702 vote majority in Ohariu-Belmont at the 2005 election, United's performance was less impressive. In 2005 it won just 5.6% of the party vote in an electorate dominated by the big two parties: National came out on top in the party vote with 43.1%, beating Labour by 3.6%, having been reduced to 24.4% three years earlier. Ohariu was an electorate based around north and western Wellington, contested between 1978 and 1990. A substantial redrawing of Wellington's boundaries ahead of the last First Past the Post election in 1993 led to Ohariu being divided between Wellington-Karori and the new electorate of Onslow. Dunne a member of the Labour Party, was the MP for the old Ohariu between 1984 until its abolition, won Onslow in 1993. Key National Labour United Future Green Members of Parliament elected from party lists in elections where that person unsuccessfully contested the Ōhāriu electorate.

Unless otherwise stated, all MPs terms ended at general elections. Electorate: 46,740 McRobie, Alan. Electoral Atlas of New Zealand. Wellington: GP Books. ISBN 0-477-01384-8. Wilson, James Oakley. New Zealand Parliamentary Record, 1840–1984. Wellington: V. R. Ward, Govt. Printer. OCLC 154283103. Norton, Clifford. New Zealand Parliamentary Election Results 1946–1987: Occasional Publications No 1, Department of Political Science. Wellington: Victoria University of Wellington. ISBN 0-475-11200-8

Jack Silver was a Navy Pacific Fleet Champion around 1921, a Pacific Coast Lightweight boxing Champion in 1924 and a contender for the Pacific Coast Welterweight Championship in 1926. In 1925, he was the World's third ranked lightweight, he was reputed by one source to have fought 237 bouts with 200 wins. In his career he fought champions Mushy Callahan, Young Corbett III, Jackie Fields, Young Jack Thompson, he defeated Callahan in a stunning upset on July 5, 1926 just months before Callahan would take the World Light Welterweight Championship. After his retirement from professional boxing, he was a California boxing referee and judge for over twenty years. Silver was born one of eight children, on August 16, 1903 in the rough Portola district of San Francisco, California, his father from Vienna, was a tailor for ladies garments. His brother Joey Silverstein became a Welterweight boxer. Like many boxers of his era, Jack grew up selling newspapers to earn extra money for his family, he entered the Navy around 1921, at the age of eighteen, where he gained many of his boxing skills during his two-year stint.

By the time of his discharge he had earned the title of Pacific Fleet Champion. While in the Navy on June 13, 1922, he fought aboard the USS California, flagship of the Pacific fleet, a vessel known for hosting top boxing and athletic competitions. On August 17, 1923, he took the City of San Francisco Lightweight title from Bobby Allen in four rounds at the large Dreamland Rink where he was to fight regularly. Silver was a studied boxer, solid in the fundamentals, he had an accurate and lightning fast left jab, an efficient right which could knock an opponent on the mat, but knock one out. He was more a studied scientific boxer than a power hitter, his long slim build. From 1922–23, Silver fought at the Dreamland Rink in San Francisco for 52 consecutive weeks as a headliner. In early 1924, according to boxing writer Ken Blady, Silver defeated Lou Paluso of Salt Lake city for the Pacific Coast Lightweight Title, he fought Paluso again for the title on March 29, 1926 in a twelve-round draw match in Salt Lake City.

According to the Deseret News, "the local pride was superior at infighting, while the coast ace had an advantage with his long reach and was at his best on long distance slugging."Defending his Pacific Coast Lightweight Title on February 23, 1925, he fought Joe Benjamin at Recreation Park in San Francisco. The fight attracted 20,000 spectators, was at the time the largest attendance for a lightweight bout in California history. Silver was down in the third round for a count of five, Benjamin won the controversial ten-round decision; this fight was an elimination bout for the World Lightweight Title. On April 16, 1926, Silver defeated Oakland Jimmy Duffy, Pacific Coast Welterweight Champion 1922–25, in ten rounds at his favorite haunt Dreamland Rink in San Francisco. Author Ken Blady wrote that Silver won the Pacific Coast Welterweight Championship as a result of this or an earlier fight with Duffy. On July 5, 1926, Silver faced the next Light Welterweight World Champion Mushy Callahan in Ewing Field in San Francisco before a huge crowd of 18,000, with Silver impressively winning the referee's decision and every round.

Callahan would hold the Light Welterweight Championship from September 21, 1926 until 1930. Reflecting on the Callahan fight two years the San Jose News wrote "In his prime Silver was the fastest Jr. Welterweight on the Pacific Coast, giving Mushy Callahan the surprise of his life... Callahan... expected to find a pushover, but was handed a lacing by the San Francisco battler." By late 1926, Silver was still a competent boxer, who now fought closer to the Jr. welterweight division, but no longer as a top ranked contender. On December 21, 1926, he lost to the former Olympic champion Jackie Fields in a four-round TKO at Dreamland Rink in San Francisco. Silver lost to 1933 World Welterweight Champion Young Corbett III on June 7, 1927 in a close ten round bout in Fresno, California; as a result of his losses to Young Corbett III, Jackie Fields, Silver retired from professional boxing in 1929. He said in an interview "I lost my touch." In a disappointing loss to 1930 Welterweight Champion, Young Jack Thompson, on September 28, 1926, in an eighth-round TKO in Los Angeles, Silver's jaw was broken.

Silver married Bess O'Connor around 1932, had a long marriage with a large family. On October 9, 1937 Silver was scheduled to box in a benefit exhibition at Legion Stadium in Los Angeles for Wad Wadheim, a fight promoter who had suffered a stroke. Among the fifty or so boxing greats that participated were triple World Champion Henry Armstrong, Silver's opponents' Jackie Fields, Mushy Callahan, Young Jack Thompson, Abe'The Newsboy" Hollandersky, Fidel La Barba, ex-Middleweight champion Al McCoy, Jim Jeffries, Maxie Rosenbloom. Silver worked as a boxing referee after his retirement from professional prizefighting, his lengthy career as a California boxing referee stretched from 1939 to 1962 and he refereed about 80 matches, including two USA sanctioned State Titles. He worked as a California boxing judge as well from 1947 to 1968, judging the California State Light Heavyweight Title on August 21, 1968 in Oakland. During his career he judged at least forty-two boxing matches according to his BoxRec record.

In his retirement from boxing, he worked as a Salesman for the Ranier Brewing Company. During the 1940s, when boxing and refereeing jobs were scarce, Silver became a sought after boxing instructor in Hollywood, where he helped tutor actors James C