Misplaced Pages

#896103

126-407: Native American petroglyphs have been discovered within the park on cliffs overlooking Difficult Run. The Patowmack Canal, which George Washington partially funded, was a one-mile (1.6 km) bypass canal that began operating in 1785 to give small barges the opportunity to skirt around the falls and to distribute manufactured goods upstream and raw materials downstream. The park visitor center had

252-557: A Cherokee ancestor on the Dawes Rolls, although all Cherokee Freedmen and their descendants had been members since 1866. As of 2004, various Native Americans are wary of attempts by others to gain control of their reservation lands for natural resources, such as coal and uranium in the West. The State of Maine is the only State House Legislature that allows Representatives from Indian Tribes. The three nonvoting members represent

378-401: A balancing compression stress in the downstream face, providing additional economy. For this type of dam, it is essential to have an impervious foundation with high bearing strength. Permeable foundations have a greater likelihood of generating uplift pressures under the dam. Uplift pressures are hydrostatic pressures caused by the water pressure of the reservoir pushing up against the bottom of

504-465: A body of law, Jim Crow institutionalized economic, educational, and social disadvantages for Native Americans, and other people of color living in the south. Native American identity was especially targeted by a system that only wanted to recognize white or colored, and the government began to question the legitimacy of some tribes because they had intermarried with African Americans. Native Americans were also discriminated and discouraged from voting in

630-544: A dam as "jurisdictional" or "non-jurisdictional" varies by location. In the United States, each state defines what constitutes a non-jurisdictional dam. In the state of Colorado a non-jurisdictional dam is defined as a dam creating a reservoir with a capacity of 100 acre-feet or less and a surface area of 20 acres or less and with a height measured as defined in Rules 4.2.5.1. and 4.2.19 of 10 feet or less. In contrast,

756-499: A dam that directed waterflow. It was finished in 251 BC. A large earthen dam, made by Sunshu Ao , the prime minister of Chu (state) , flooded a valley in modern-day northern Anhui Province that created an enormous irrigation reservoir (100 km (62 mi) in circumference), a reservoir that is still present today. Roman dam construction was characterized by "the Romans' ability to plan and organize engineering construction on

882-493: A distinct vertical curvature to it as well lending it the vague appearance of a concave lens as viewed from downstream. The multiple-arch dam consists of a number of single-arch dams with concrete buttresses as the supporting abutments, as for example the Daniel-Johnson Dam , Québec, Canada. The multiple-arch dam does not require as many buttresses as the hollow gravity type but requires a good rock foundation because

1008-495: A federal Indian trust relationship are based. Cultural activism since the late 1960s has increased the participation of Indigenous peoples in American politics. It has also led to expanded efforts to teach and preserve Indigenous languages for younger generations, and to establish a more robust cultural infrastructure: Native Americans have founded independent newspapers and online media outlets, including First Nations Experience ,

1134-478: 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 particularly Roman concrete allowed for much larger dam structures than previously built, such as the Lake Homs Dam , possibly the largest water barrier to that date, and

1260-470: A large degree of tribal sovereignty . For this reason, many Native American reservations are still independent of state law and the actions of tribal citizens on these reservations are subject only to tribal courts and federal law. The Indian Citizenship Act of 1924 granted US citizenship to all Native Americans born in the US who had not yet obtained it. This emptied the "Indians not taxed" category established by

1386-511: A minor tributary of the Nieuwe Maas . The central square of Amsterdam, covering the original site of the 800-year-old dam, still carries the name Dam Square . The Romans were the first to build arch dams , where the reaction forces from the abutment stabilizes the structure from the external hydrostatic pressure , but it was only in the 19th century that the engineering skills and construction materials available were capable of building

SECTION 10

#1732783165897

1512-724: A more collective basis than the culture which Europeans were familiar with. Most Indigenous American tribes treated their hunting grounds and agricultural lands as land that could be used by their entire tribe. Europeans had developed concepts of individual property rights with respect to land that were extremely different. The differences in cultures, as well as the shifting alliances among different nations during periods of warfare, caused extensive political tension, ethnic violence, and social disruption. Native Americans suffered high fatality rates from contact with European diseases that were new to them, and to which they had not acquired immunity . Smallpox epidemics are thought to have caused

1638-509: A notable increase in interest in SHPs. Couto and Olden (2018) conducted a global study and found 82,891 small hydropower plants (SHPs) operating or under construction. Technical definitions of SHPs, such as their maximum generation capacity, dam height, reservoir area, etc., vary by country. A dam is non-jurisdictional when its size (usually "small") excludes it from being subject to certain legal regulations. The technical criteria for categorising

1764-649: A profession based on a rigorously applied scientific theoretical framework. This new emphasis was centered around the engineering faculties of universities in France and in the United Kingdom. William John Macquorn Rankine at the University of Glasgow pioneered the theoretical understanding of dam structures in his 1857 paper On the Stability of Loose Earth . Rankine theory provided a good understanding of

1890-475: A resolution recommending that the federal and legislative branches of the U.S. government terminate tribal governments. In 2007, a group of Democratic Party congressmen and congresswomen introduced a bill in the U.S. House of Representatives to terminate Federal recognition of the Cherokee Nation . This was related to their voting to exclude Cherokee Freedmen as members of the tribe unless they had

2016-566: A settling pond, and a 1,000 m (3,300 ft) canal to a distribution tank. These works were not finished until 325 AD when the dam permitted the irrigation of 25,000 acres (100 km ). Eflatun Pınar is a Hittite dam and spring temple near Konya , Turkey. It is thought to date from the Hittite empire between the 15th and 13th centuries BC. The Kallanai is constructed of unhewn stone, over 300 m (980 ft) long, 4.5 m (15 ft) high and 20 m (66 ft) wide, across

2142-400: A variety of diseases, but in many cases this happened long after Europeans first arrived. When severe epidemics did hit, it was often less because Native bodies lack immunity than because European colonialism disrupted Native Communities and damaged their resources, making them more vulnerable to pathogens." After the thirteen British colonies revolted against Great Britain and established

2268-408: A whole dam itself, that dam also would be held in place by gravity, i.e., there is no tension in the upstream face of the dam holding the top of the dam down. The designer does this because it is usually more practical to make a dam of material essentially just piled up than to make the material stick together against vertical tension. The shape that prevents tension in the upstream face also eliminates

2394-537: Is condescending for such lands to be considered "held in trust" and regulated in any fashion by any entity other than their own tribes. Some tribal groups have been unable to document the cultural continuity required for federal recognition. To achieve federal recognition and its benefits, tribes must prove continuous existence since 1900. The federal government has maintained this requirement, in part because through participation on councils and committees, federally recognized tribes have been adamant about groups' satisfying

2520-424: Is dependent on the strength of the side wall abutments, hence not only should the arch be well seated on the side walls but also the character of the rock should be carefully inspected. Two types of single-arch dams are in use, namely the constant-angle and the constant-radius dam. The constant-radius type employs the same face radius at all elevations of the dam, which means that as the channel grows narrower towards

2646-538: Is illegal. An average of seven drownings per year occur in the Potomac River in the park vicinity, most of them alcohol -related even though consumption of alcoholic beverages is illegal within the park. Native Americans in the United States This is an accepted version of this page Native Americans (also called American Indians , First Americans , or Indigenous Americans ) are

SECTION 20

#1732783165897

2772-608: Is known as the " Kelp Highway ". The early inhabitants by land were classified as Paleo-Indians , who spread throughout the Americas, diversifying into numerous culturally distinct nations. Major Paleo-Indian cultures included the Clovis and Folsom traditions , identified through unique spear points and large-game hunting methods, especially during the Lithic stage . Around 8000 BCE, as the climate stabilized, new cultural periods like

2898-480: Is often used in conjunction with dams to generate electricity. A dam can also be used to collect or store water which can be evenly distributed between locations. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees (also known as dikes ) are used to manage or prevent water flow into specific land regions. The word dam can be traced back to Middle English , and before that, from Middle Dutch , as seen in

3024-471: Is sloped the distribution is more complicated. The normal component of the weight of the arch ring may be taken by the arch action, while the normal hydrostatic pressure will be distributed as described above. For this type of dam, firm reliable supports at the abutments (either buttress or canyon side wall) are more important. The most desirable place for an arch dam is a narrow canyon with steep side walls composed of sound rock. The safety of an arch dam

3150-733: Is the largest tribe if only full-blood individuals are counted; the Navajo are the tribe with the highest proportion of full-blood individuals, 86.3%. The Cherokee have a different history; it is the largest tribe, with 819,000 individuals, and it has 284,000 full-blood individuals. As of 2012, 70% of Native Americans live in urban areas, up from 45% in 1970 and 8% in 1940. Urban areas with significant Native American populations include Minneapolis, Denver, Phoenix, Tucson, Chicago, Oklahoma City, Houston, New York City, and Los Angeles. Many live in poverty. Racism, unemployment, drugs and gangs are common problems which Indian social service organizations such as

3276-399: Is the more widely used of the two, though the hollow dam is frequently more economical to construct. Grand Coulee Dam is a solid gravity dam and Braddock Locks & Dam is a hollow gravity dam. A gravity dam can be combined with an arch dam into an arch-gravity dam for areas with massive amounts of water flow but less material available for a pure gravity dam. The inward compression of

3402-590: Is the thinnest arch dam in the world and one of the oldest arch dams in Asia. It was constructed some 700 years ago in Tabas county , South Khorasan Province , Iran . It stands 60 meters tall, and in crest is a one meter width. Some historians believe the dam was built by Shāh Abbās I, whereas others believe that he repaired it. In the Netherlands , a low-lying country, dams were often built to block rivers to regulate

3528-564: The American Indian Movement (AIM) drawing attention to Indigenous rights. Landmark legislation like the Indian Self-Determination and Education Assistance Act of 1975 recognized tribal autonomy, leading to the establishment of Native-run schools and economic initiatives. Tribal sovereignty has continued to evolve, with legal victories and federal acknowledgments supporting cultural revitalization. By

3654-543: The Archaic stage arose, during which hunter-gatherer communities developed complex societies across North America. The Mound Builders created large earthworks, such as at Watson Brake and Poverty Point , which date to 3500 BCE and 2200 BCE, respectively, indicating early social and organizational complexity. By 1000 BCE, Native societies in the Woodland period developed advanced social structures and trade networks, with

3780-518: The Census Bureau until 1930: American Indians and Alaska Natives as percentage of the total population between 1880 and 2020: Absolute numbers of American Indians and Alaska Natives between 1880 and 2020 (since 1890 according to the Census Bureau ): 78% of Native Americans live outside a reservation. Full-blood individuals are more likely to live on a reservation than mixed-blood individuals. The Navajo , with 286,000 full-blood individuals,

3906-664: The Dawes Act , which undermined communal landholding. A justification for the policy of conquest and subjugation of the Indigenous people emanated from the stereotyped perceptions of Native Americans as "merciless Indian savages" (as described in the United States Declaration of Independence ). Sam Wolfson in The Guardian writes, "The declaration's passage has often been cited as an encapsulation of

Great Falls Park - Misplaced Pages Continue

4032-657: 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 then release it to surrounding lands. The lake called Mer-wer or Lake Moeris covered 1,700 km (660 sq mi) and is known today as Birket Qarun. By the mid-late third millennium BC, an intricate water-management system in Dholavira in modern-day India

4158-579: The Harbaqa Dam , both in Roman Syria . The highest Roman dam was the Subiaco Dam near Rome ; its record height of 50 m (160 ft) remained unsurpassed until its accidental destruction in 1305. 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

4284-791: The Hopewell tradition connecting the Eastern Woodlands to the Great Lakes and the Gulf of Mexico . This period led to the Mississippian culture , with large urban centers like Cahokia —a city with complex mounds and a population exceeding 20,000 by 1250 CE. From the 15th century onward, European contact drastically reshaped the Americas. Explorers and settlers introduced diseases, causing massive Indigenous population declines, and engaged in violent conflicts with Native groups. By

4410-680: The Indigenous peoples of the United States , particularly of the lower 48 states and Alaska . They may also include any Americans whose origins lie in any of the indigenous peoples of North or South America. The United States Census Bureau publishes data about "American Indians and Alaska Natives ", whom it defines as anyone "having origins in any of the original peoples of North and South America ... and who maintains tribal affiliation or community attachment". The census does not, however, enumerate "Native Americans" as such, noting that

4536-758: The Indigenous peoples of Canada are generally known as First Nations , Inuit and Métis ( FNIM ). The history of Native Americans in the United States began before the founding of the U.S., tens of thousands of years ago with the settlement of the Americas by the Paleo-Indians . The Eurasian migration to the Americas occurred over millennia via Beringia , a land bridge between Siberia and Alaska , as early humans spread southward and eastward, forming distinct cultures and societies. Archaeological evidence suggests these migrations began 60,000 years ago and continued until around 12,000 years ago. Some may have arrived even before this time fishing in kayaks along what

4662-625: The Mississippi River , in order to accommodate continued European American expansion. This resulted in what amounted to the ethnic cleansing or genocide of many tribes, who were subjected to brutal forced marches . The most infamous of these came to be known as the Trail of Tears . Contemporary Native Americans have a unique relationship with the United States because they may be members of nations, tribes, or bands that have sovereignty and treaty rights upon which federal Indian law and

4788-620: The Senate Indian Affairs Committee endorsed a bill that would grant federal recognition to tribes in Virginia. As of 2000 , the largest groups in the United States by population were Navajo , Cherokee , Choctaw , Sioux , Chippewa , Apache , Blackfeet , Iroquois , and Pueblo . In 2000, eight of ten Americans with Native American ancestry were of mixed ancestry. It is estimated that by 2100 that figure will rise to nine out of ten. The civil rights movement

4914-464: The U.S. Capitol . During the construction of the canal, blasting powder , which at the time was essentially gunpowder , was used to blast through solid rocks. This is one of the first known examples of blasting powder being used for engineering purposes anywhere in the world. The canal was never a profitable enterprise. With the completion of the Chesapeake and Ohio Canal on the opposite side of

5040-734: The United States Constitution , allowed Natives to vote in elections, and extended the Fourteenth Amendment protections granted to people "subject to the jurisdiction" of the United States. However, some states continued to deny Native Americans voting rights for decades. Titles II through VII of the Civil Rights Act of 1968 comprise the Indian Civil Rights Act, which applies to Native American tribes and makes many but not all of

5166-645: The University of Oxford published a study of the cost of large dams – based on the largest existing dataset – documenting significant cost overruns for a majority of dams and questioning whether benefits typically offset costs for such dams. Dams can be formed by human agency, natural causes, or even by the intervention of wildlife such as beavers . Man-made dams are typically classified according to their size (height), intended purpose or structure. Based on structure and material used, dams are classified as easily created without materials, arch-gravity dams , embankment dams or masonry dams , with several subtypes. In

Great Falls Park - Misplaced Pages Continue

5292-542: The falls was also considered but, due to a strong lobby to eliminate additional bridges over the Potomac and concerns over environmental impacts, the project was never undertaken. The park continues to provide picnic grounds and a visitor center but the carousel that operated between 1954 and 1972 was destroyed by a flood caused by Hurricane Agnes . Direct access to the park is usually by way of Georgetown Pike (Virginia Route 193) and Old Dominion Drive. Major highways in

5418-565: The first written accounts of the contact were provided by Europeans . Ethnographers classify the Indigenous peoples of North America into ten geographical regions which are inhabited by groups of people who share certain cultural traits, called cultural areas. The ten cultural areas are: At the time of the first contact, the Indigenous cultures were different from those of the proto-industrial and mostly Christian immigrants. Some Northeastern and Southwestern cultures, in particular, were matrilineal and they were organized and operated on

5544-537: The 19th century, westward U.S. expansion, rationalized by Manifest destiny , pressured tribes into forced relocations like the Trail of Tears , which decimated communities and redefined Native territories. Despite resistance in events like the Sioux Uprising and Battle of Little Bighorn , Native American lands continued to be reduced through policies like the Indian Removal Act of 1830 and later

5670-513: The 21st century, Native Americans had achieved increased control over tribal lands and resources, although many communities continue to grapple with the legacy of displacement and economic challenges. Urban migration has also grown, with over 70% of Native Americans residing in cities by 2012, navigating issues of cultural preservation and discrimination. Continuing legal and social efforts address these concerns, building on centuries of resilience and adaptation that characterize Indigenous history across

5796-455: The 48 states and Alaska. Native American population rebounded sharply from 1950, when they numbered 377,273; it reached 551,669 in 1960, 827,268 in 1970, with an annual growth rate of 5%, four times the national average. Total spending on Native Americans averaged $ 38 million a year in the late 1920s, dropping to a low of $ 23 million in 1933, and returning to $ 38 million in 1940. The Office of Indian Affairs counted more American Indians than

5922-647: The Americas , including Mesoamerican peoples such as the Maya , as well as Canadian and South American natives . In 2022, 634,503 Indigenous people in the United States identified with Central American Indigenous groups, 875,183 identified with the Indigenous people of Mexico , and 47,518 identified with Canadian First Nations . Of the 3.2 million Americans who identified as American Indian or Alaska Native alone in 2022, around 45% are of Hispanic or Latino ethnicity, with this number growing as increasing numbers of Indigenous people from Latin American countries immigrate to

6048-399: The Americas. According to the 2020 census, the U.S. population was 331.4 million. Of this, 3.7 million people, or 1.1 percent, reported American Indian or Alaska Native ancestry alone. In addition, 5.9 million people (1.8 percent), reported American Indian or Alaska Native in combination with one or more other races. The definition of American Indian or Alaska Native used in the 2010 census

6174-544: The British began construction in 1898. The project was designed by Sir William Willcocks and involved several eminent engineers of the time, including Sir Benjamin Baker and Sir John Aird , whose firm, John Aird & Co. , was the main contractor. Capital and financing were furnished by Ernest Cassel . When initially constructed between 1899 and 1902, nothing of its scale had ever before been attempted; on completion, it

6300-520: The Colorado River is a constant-angle arch dam. A similar type is the double-curvature or thin-shell dam. Wildhorse Dam near Mountain City, Nevada , in the United States is an example of the type. This method of construction minimizes the amount of concrete necessary for construction but transmits large loads to the foundation and abutments. The appearance is similar to a single-arch dam but with

6426-680: The Colorado River. By 1997, there were an estimated 800,000 dams worldwide, with some 40,000 of them over 15 meters high. Early dam building took place in Mesopotamia and the Middle East . Dams were used to control water levels, for Mesopotamia's weather affected the Tigris and Euphrates Rivers. The earliest known dam is the Jawa Dam in Jordan , 100 kilometres (62 mi) northeast of

SECTION 50

#1732783165897

6552-552: The Ghost Dance properly, the European American colonists would vanish, the bison would return, and the living and the dead would be reunited in an Eden ic world. On December 29 at Wounded Knee, gunfire erupted, and U.S. soldiers killed up to 300 Indians, mostly old men, women, and children. Days after the massacre, the author L. Frank Baum wrote: The Pioneer has before declared that our only safety depends upon

6678-579: The Indians were destined to vanish under the pressure of white civilization, stating in an 1886 lecture: I don't go so far as to think that the only good Indians are dead Indians, but I believe nine out of ten are, and I shouldn't like to inquire too closely into the case of the tenth. One of the last and most notable events during the Indian wars was the Wounded Knee Massacre in 1890. In

6804-578: The International Scale of River Difficulty. The first kayaker to run them was Tom McEwan in 1975, but only since the early 1990s have the Falls been a popular destination for expert whitewater boaters in the DC area. Below the falls, through Mather Gorge, the river is rated class 2-3 and has been a very popular kayaking run since the 1960s. Entry into the water above the falls from the Virginia side

6930-746: The Little Earth housing complex in Minneapolis attempt to address. Below are numbers for U.S. citizens self-identifying to selected tribal groupings, according to the 2010 U.S. census. There are 573 federally recognized tribal governments and 326 Indian reservations in the United States. These tribes possess the right to form their own governments, to enforce laws (both civil and criminal) within their lands, to tax, to establish requirements for membership, to license and regulate activities, to zone, and to exclude persons from tribal territories. Limitations on tribal powers of self-government include

7056-714: The Middle Ages, dams were built in the Netherlands to regulate water levels and prevent sea intrusion. In the 19th century, large-scale arch dams were constructed around the British Empire, marking advances in dam engineering techniques. The era of large dams began with the construction of the Aswan Low Dam in Egypt in 1902. The Hoover Dam, a massive concrete arch-gravity dam, was built between 1931 and 1936 on

7182-773: The Park was bought from the receivership by the Fairfax Park Authority using funds set aside to purchase right-of-way for the George Washington Memorial Parkway . The George Washington Memorial Parkway was developed to ensure the easy linkage of George Washington's most visited places. Great Falls Park was a part of the Northern Virginia Parks system until it was transferred to the NPS in 1966. A proposed bridge to span

7308-492: The Penobscot Nation, Houlton Band of Maliseet Indians, and Passamaquoddy Tribe . These representatives can sponsor any legislation regarding American Indian affairs or co-sponsor any pending State of Maine legislation. Maine is unique regarding Indigenous leadership representation. In the state of Virginia , Native Americans face a unique problem. Until 2017 Virginia previously had no federally recognized tribes but

7434-511: The Secretary of State, rather than the Bureau of Indian Affairs . The Bureau of Indian Affairs reports on its website that its "responsibility is the administration and management of 55,700,000 acres (225,000 km ) of land held in trust by the United States for American Indians, Indian tribes, and Alaska Natives ". Many Native Americans and advocates of Native American rights believe that it

7560-478: The U.S. federal government's claim to recognize the "sovereignty" of Native American peoples falls short, given that the United States wishes to govern Native American peoples and treat them as subject to U.S. law. Such advocates contend that full respect for Native American sovereignty would require the U.S. government to deal with Native American peoples in the same manner as any other sovereign nation, handling matters related to relations with Native Americans through

7686-405: The US and more Latinos self-identify with indigenous heritage. Of groups Indigenous to the United States, the largest self-reported tribes are Cherokee (1,449,888), Navajo (434,910), Choctaw (295,373), Blackfeet (288,255), Sioux (220,739), and Apache (191,823). 205,954 respondents specified an Alaska Native identity. Native Hawaiians are counted separately from Native Americans by

SECTION 60

#1732783165897

7812-495: The United States alone, there are approximately 2,000,000 or more "small" dams that are not included in the Army Corps of Engineers National Inventory of dams . Records of small dams are kept by state regulatory agencies and therefore information about small dams is dispersed and uneven in geographic coverage. Countries worldwide consider small hydropower plants (SHPs) important for their energy strategies, and there has been

7938-600: The United States was established, Native American tribes were considered semi-independent nations, because they generally lived in communities which were separate from communities of white settlers . The federal government signed treaties at a government-to-government level until the Indian Appropriations Act of 1871 ended recognition of independent Native nations, and started treating them as "domestic dependent nations" subject to applicable federal laws. This law did preserve rights and privileges, including

8064-458: The United States, President George Washington and Secretary of War Henry Knox conceived the idea of " civilizing " Native Americans in preparation for their assimilation as U.S. citizens. Assimilation, whether it was voluntary, as it was with the Choctaw , or forced , was consistently maintained as a matter of policy by consecutive American administrations. During the 19th century,

8190-524: The World Commission on Dams also includes in the "large" category, dams which are between 5 and 15 m (16 and 49 ft) high with a reservoir capacity of more than 3 million cubic metres (2,400  acre⋅ft ). Hydropower dams can be classified as either "high-head" (greater than 30 m in height) or "low-head" (less than 30 m in height). As of 2021 , ICOLD's World Register of Dams contains 58,700 large dam records. The tallest dam in

8316-403: The arch dam, stability is obtained by a combination of arch and gravity action. If the upstream face is vertical the entire weight of the dam must be carried to the foundation by gravity, while the distribution of the normal hydrostatic pressure between vertical cantilever and arch action will depend upon the stiffness of the dam in a vertical and horizontal direction. When the upstream face

8442-666: The back of the dam through a large pipe to drive a water wheel and watermill . In the 10th century, Al-Muqaddasi described several dams in Persia. He reported that one in Ahwaz was more than 910 m (3,000 ft) long, and that it had many water-wheels raising the water into aqueducts through which it flowed into reservoirs of the city. Another one, the Band-i-Amir Dam, provided irrigation for 300 villages. Shāh Abbās Arch (Persian: طاق شاه عباس), also known as Kurit Dam ,

8568-438: The bottom of the dam the central angle subtended by the face of the dam becomes smaller. Jones Falls Dam , in Canada, is a constant radius dam. In a constant-angle dam, also known as a variable radius dam, this subtended angle is kept constant and the variation in distance between the abutments at various levels is taken care of by varying the radii. Constant-radius dams are much less common than constant-angle dams. Parker Dam on

8694-408: The bottom portions of two wooden lock gates from the canal excavated in the 1980s, which can still be found in the park today. The gates survived from at least the 1830s and were found during restoration projects on stonework which were erected for the canal locks. Stonemason marks found on the stones are unique to each artisan and are identical to some found in foundation stones of the White House and

8820-402: The buttress loads are heavy. In a gravity dam, the force that holds the dam in place against the push from the water is Earth's gravity pulling down on the mass of the dam. The water presses laterally (downstream) on the dam, tending to overturn the dam by rotating about its toe (a point at the bottom downstream side of the dam). The dam's weight counteracts that force, tending to rotate the dam

8946-450: The capital Amman . This gravity dam featured an originally 9-metre-high (30 ft) and 1 m-wide (3.3 ft) stone wall, supported by a 50 m-wide (160 ft) earthen rampart. The structure is dated to 3000 BC. However, the oldest continuously operational dam is Lake Homs Dam , built in Syria between 1319-1304 BC. The Ancient Egyptian Sadd-el-Kafara Dam at Wadi Al-Garawi, about 25 km (16 mi) south of Cairo ,

9072-407: The census, being classified as Pacific Islanders . According to 2022 estimates, 714,847 Americans reported Native Hawaiian ancestry. The 2010 census permitted respondents to self-identify as being of one or more races. Self-identification dates from the census of 1960; prior to that the race of the respondent was determined by the opinion of the census taker. The option to select more than one race

9198-646: The city. The masonry arch dam wall was designed by Lieutenant Percy Simpson who was influenced by the advances in dam engineering techniques made by the Royal Engineers in India . The dam cost £17,000 and was completed in 1856 as the first engineered dam built in Australia, and the second arch dam in the world built to mathematical specifications. The first such dam was opened two years earlier in France . It

9324-506: The cliffs in Mather Gorge above the Potomac. The park contains a large picnic area and sufficient parking for 600 vehicles . On busy weekends, all the parking may fill up by early in the morning, creating delays and temporary closures lasting up to several hours. The NPS does not permit camping in the park. The falls total 76 feet (20 m) over a series of major cascades . The Great Falls are rated Class 5-6 Whitewater according to

9450-447: The colonization process as comprising genocide against Native Americans. As part of a policy of white settler colonialism , European settlers continued to wage war and perpetrated massacres against Native American peoples, removed them from their ancestral lands , and subjected them to one-sided government treaties and discriminatory government policies. Into the 20th century, these policies focused on forced assimilation . When

9576-671: The construction of the Rideau Canal in Canada near modern-day Ottawa and built a series of curved masonry dams as part of the waterway system. In particular, the Jones Falls Dam , built by John Redpath , was completed in 1832 as the largest dam in North America and an engineering marvel. In order to keep the water in control during construction, two sluices , artificial channels for conducting water, were kept open in

9702-469: The dam by the water reduces the lateral (horizontal) force acting on the dam. Thus, the gravitational force required by the dam is lessened, i.e., the dam does not need to be so massive. This enables thinner dams and saves resources. A barrage dam is a special kind of dam that consists of a line of large gates that can be opened or closed to control the amount of water passing the dam. The gates are set between flanking piers which are responsible for supporting

9828-533: The dam was submitted by a consortium called Six Companies, Inc. Such a large concrete structure had never been built before, and some of the techniques were unproven. The torrid summer weather and the lack of facilities near the site also presented difficulties. Nevertheless, Six Companies turned over the dam to the federal government on 1 March 1936, more than two years ahead of schedule. By 1997, there were an estimated 800,000 dams worldwide, some 40,000 of them over 15 m (49 ft) high. In 2014, scholars from

9954-605: The dam. If large enough uplift pressures are generated there is a risk of destabilizing the concrete gravity dam. On a suitable site, a gravity dam can prove to be a better alternative to other types of dams. When built on a solid foundation, the gravity dam probably represents the best-developed example of dam building. Since the fear of flood is a strong motivator in many regions, gravity dams are built in some instances where an arch dam would have been more economical. Gravity dams are classified as "solid" or "hollow" and are generally made of either concrete or masonry. The solid form

10080-407: The dam. The first was near the base of the dam on its east side. A second sluice was put in on the west side of the dam, about 20 ft (6.1 m) above the base. To make the switch from the lower to upper sluice, the outlet of Sand Lake was blocked off. Hunts Creek near the city of Parramatta , Australia , was dammed in the 1850s, to cater to the demand for water from the growing population of

10206-450: The dams' potential range and magnitude of environmental disturbances. The International Commission on Large Dams (ICOLD) defines a "large dam" as "A dam with a height of 15 m (49 ft) or greater from lowest foundation to crest or a dam between 5 m (16 ft) metres and 15 metres impounding more than 3 million cubic metres (2,400  acre⋅ft )". "Major dams" are over 150 m (490 ft) in height. The Report of

10332-522: The dehumanizing attitude toward Indigenous Americans that the US was founded on." Native American nations on the plains in the west continued armed conflicts with the U.S. throughout the 19th century, through what were called generally Indian Wars . Notable conflicts in this period include the Dakota War , Great Sioux War , Snake War , Colorado War , and Texas-Indian Wars . Expressing the frontier anti-Indian sentiment, Theodore Roosevelt believed

10458-535: The falls. Located at the end of an electric trolley line that began in Georgetown, Washington, D.C. , the park contained picnic grounds, a dance pavilion, and a carousel . In the evenings, a searchlight illuminated the falls. After the railroad went into receivership in 1935 and the Great Falls line was abandoned, the Park was leased by the receivership to a series of concessionaires. In January 1953,

10584-502: The falls. The NPS operates a visitor center near the falls. Fifteen miles (24 km) of hiking trails traverse the park and follow a small stream known as Difficult Run . A scenic trail near the river travels upstream from a landing at the mouth of Difficult Run, climbs to the top of Mather Gorge and passes the falls, a dam , and a reservoir before ending in Fairfax County's Riverbend Park. Rock climbers frequent

10710-977: The first Native American television channel; established Native American studies programs, tribal schools universities , museums, and language programs. Literature is at the growing forefront of American Indian studies in many genres, with the notable exception of fiction—some traditional American Indians experience fictional narratives as insulting when they conflict with traditional oral tribal narratives. The terms used to refer to Native Americans have at times been controversial . The ways Native Americans refer to themselves vary by region and generation, with many older Native Americans self-identifying as "Indians" or "American Indians", while younger Native Americans often identify as "Indigenous" or "Aboriginal". The term "Native American" has not traditionally included Native Hawaiians or certain Alaskan Natives , such as Aleut , Yup'ik , or Inuit peoples. By comparison,

10836-561: The first large-scale arch dams. Three pioneering arch dams were built around the British Empire in the early 19th century. Henry Russel of the Royal Engineers oversaw the construction of the Mir Alam dam in 1804 to supply water to the city of Hyderabad (it is still in use today). It had a height of 12 m (39 ft) and consisted of 21 arches of variable span. In the 1820s and 30s, Lieutenant-Colonel John By supervised

10962-742: The first was the Roman-built dam bridge in Dezful , which could raise water 50 cubits (c. 23 m) to supply the town. Also diversion dams were known. Milling dams were introduced which the Muslim engineers called the Pul-i-Bulaiti . The first was built at Shustar on the River Karun , Iran, and many of these were later built in other parts of the Islamic world . Water was conducted from

11088-534: The force of water. A fixed-crest dam is a concrete barrier across a river. Fixed-crest dams are designed to maintain depth in the channel for navigation. They pose risks to boaters who may travel over them, as they are hard to spot from the water and create induced currents that are difficult to escape. There is variability, both worldwide and within individual countries, such as in the United States, in how dams of different sizes are categorized. Dam size influences construction, repair, and removal costs and affects

11214-525: The greatest loss of life for Indigenous populations. "The decline of native American populations was rapid and severe, probably the greatest demographic disaster ever. Old World diseases were the primary killer. In many regions, particularly the tropical lowlands, populations fell by 90 percent or more in the first century after the contact." Estimates of pre-Columbian population of the United States vary from 4 to 18 million. Jeffrey Ostler writes: "Most Indigenous communities were eventually afflicted by

11340-402: The guarantees of the U.S. Bill of Rights applicable within the tribes. Since the 1960s, Native American self-determination movements have resulted in positive changes to the lives of many Native Americans, though there are still many contemporary issues faced by them . Today, there are over five million Native Americans in the US, about 80% of whom live outside reservations. The states with

11466-561: The highest percentage of Native Americans are Alaska , Oklahoma , New Mexico , South Dakota , Montana , and North Dakota . Beginning toward the end of the 15th century, the migration of Europeans to the Americas led to centuries of population, cultural, and agricultural transfer and adjustment between Old and New World societies, a process known as the Columbian exchange . Because most Native American groups had preserved their histories by means of oral traditions and artwork,

11592-541: The ideology known as manifest destiny became integral to the American nationalist movement. Westward expansion of European American populations after the American Revolution resulted in increasing pressure on Native Americans and their lands, warfare, and rising tensions. In 1830, the U.S. Congress passed the Indian Removal Act , authorizing the federal government to relocate Native Americans from their homelands within established states to lands west of

11718-521: The latter term can encompass a broader set of groups, e.g. Native Hawaiians , which it tabulates separately. The European colonization of the Americas from 1492 resulted in a precipitous decline in the size of the Native American population because of newly introduced diseases , including weaponized diseases and biological warfare by colonizers, wars , ethnic cleansing , and enslavement . Numerous scholars have classified elements of

11844-645: 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 regulating structures 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

11970-633: The names of many old cities, such as Amsterdam and Rotterdam . Ancient dams were built in Mesopotamia and the Middle East for water control. The earliest known dam is the Jawa Dam in Jordan , dating to 3,000 BC. Egyptians also built dams, such as Sadd-el-Kafara Dam for flood control. In modern-day India, Dholavira had an intricate water-management system with 16 reservoirs and dams. The Great Dam of Marib in Yemen, built between 1750 and 1700 BC,

12096-683: The other basic dam designs which had been 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 (see List of Roman dams ). Roman workforces also were the first to build dam bridges, such as the Bridge of Valerian in Iran. In Iran , bridge dams such as the Band-e Kaisar were used to provide hydropower through water wheels , which often powered water-raising mechanisms. One of

12222-429: The other way about its toe. The designer ensures that the dam is heavy enough that the dam's weight wins that contest. In engineering terms, that is true whenever the resultant of the forces of gravity acting on the dam and water pressure on the dam acts in a line that passes upstream of the toe of the dam. The designer tries to shape the dam so if one were to consider the part of the dam above any particular height to be

12348-607: The principles behind dam design. In France, J. Augustin Tortene de Sazilly explained the mechanics of vertically faced masonry gravity dams, and Zola's dam was the first to be built on the basis of these principles. The era of large dams was initiated with the construction of the Aswan Low Dam in Egypt in 1902, a gravity masonry buttress dam on the Nile River . Following their 1882 invasion and occupation of Egypt ,

12474-629: The problem was quickly resolved. King would later make trips to Arizona visiting Native Americans on reservations, and in churches encouraging them to be involved in the Civil Rights Movement. In King's book Why We Can't Wait he writes: Dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation , human consumption , industrial use , aquaculture , and navigability . Hydropower

12600-410: The problems of Virginia Indians in establishing documented continuity of identity, due to the work of Walter Ashby Plecker (1912–1946). As registrar of the state's Bureau of Vital Statistics, he applied his own interpretation of the one-drop rule , enacted in law in 1924 as the state's Racial Integrity Act. It recognized only two races: "white" and "colored". Plecker, a segregationist , believed that

12726-511: The right to label arts and crafts as Native American and permission to apply for grants that are specifically reserved for Native Americans. But gaining federal recognition as a tribe is extremely difficult; to be established as a tribal group, members have to submit extensive genealogical proof of tribal descent and continuity of the tribe as a culture. In July 2000, the Washington State Republican Party adopted

12852-557: The river, and the oncoming age of railroads , the project was abandoned in 1830. The canal is a Civil Engineering Landmark as well as a Virginia Historic Landmark. Along the trails, the ruins of the small town of Matildaville, Virginia can also be found. Between 1906 and 1932, the Great Falls and Old Dominion Railroad and its successor, the Washington and Old Dominion Railway , operated an amusement park ( trolley park ) at

12978-471: The same limitations applicable to states; for example, neither tribes nor states have the power to make war, engage in foreign relations, or coin money (this includes paper currency). In addition, there are a number of tribes that are recognized by individual states , but not by the federal government. The rights and benefits associated with state recognition vary from state to state. Many Native Americans and advocates of Native American rights point out that

13104-521: The same requirements as they did. The Muwekma Ohlone of the San Francisco Bay Area are pursuing litigation in the federal court system to establish recognition. Many of the smaller eastern tribes, long considered remnants of extinct peoples, have been trying to gain official recognition of their tribal status. Several tribes in Virginia and North Carolina have gained state recognition. Federal recognition confers some benefits, including

13230-660: The south in the late 1950s after they reached out to him. At that time the remaining Creek in Alabama were trying to completely desegregate schools in their area. In this case, light-complexioned Native children were allowed to ride school buses to previously all white schools, while dark-skinned Native children from the same band were barred from riding the same buses. Tribal leaders, upon hearing of King's desegregation campaign in Birmingham, Alabama, contacted him for assistance. He promptly responded and, through his intervention,

13356-613: The southern and western states. In the south segregation was a major problem for Native Americans seeking education, but the NAACP's legal strategy would later change this. Movements such as Brown v. Board of Education was a major victory for the Civil Rights Movement headed by the NAACP , and inspired Native Americans to start participating in the Civil Rights Movement. Martin Luther King Jr. began assisting Native Americans in

13482-535: The state as "colored" and gave them lists of family surnames to examine for reclassification based on his interpretation of data and the law. This led to the state's destruction of accurate records related to families and communities who identified as Native American (as in church records and daily life). By his actions, sometimes different members of the same family were split by being classified as "white" or "colored". He did not allow people to enter their primary identification as Native American in state records. In 2009,

13608-500: The state had recognized eight. This is related historically to the greater impact of disease and warfare on the Virginia Indian populations, as well as their intermarriage with Europeans and Africans. Some people confused ancestry with culture, but groups of Virginia Indians maintained their cultural continuity. Most of their early reservations were ended under the pressure of early European settlement. Some historians also note

13734-487: The state of New Mexico defines a jurisdictional dam as 25 feet or greater in height and storing more than 15 acre-feet or a dam that stores 50 acre-feet or greater and is six feet or more in height (section 72-5-32 NMSA), suggesting that dams that do not meet these requirements are non-jurisdictional. Most US dams, 2.41 million of a total of 2.5 million dams, are not under the jurisdiction of any public agency (i.e., they are non-jurisdictional), nor are they listed on

13860-529: The state's Native Americans had been "mongrelized" by intermarriage with African Americans; to him, ancestry determined identity, rather than culture. He thought that some people of partial black ancestry were trying to " pass " as Native Americans. Plecker thought that anyone with any African heritage had to be classified as colored, regardless of appearance, amount of European or Native American ancestry, and cultural/community identification. Plecker pressured local governments into reclassifying all Native Americans in

13986-474: The total extermination of the Indians. Having wronged them for centuries, we had better, in order to protect our civilization, follow it up by one more wrong and wipe these untamed and untamable creatures from the face of the earth. In the 20th century, Native Americans served in significant numbers during World War II, marking a turning point for Indigenous visibility and involvement in broader American society. Post-war, Native activism grew, with movements such as

14112-535: The vicinity of the park which provide regional connections include the Capital Beltway (Interstate 495) , the Dulles Toll Road (Virginia Route 267) and Leesburg Pike (Virginia Route 7) . There is a $ 20 entrance fee per car for visitors who drive into the park. The park is open only during daylight hours. The park has several viewing platforms that provide visitors with vantage points overlooking

14238-406: The water level and to prevent the sea from entering the marshlands. Such dams often marked the beginning of a town or city because it was easy to cross the river at such a place, and often influenced Dutch place names. The present Dutch capital, Amsterdam (old name Amstelredam ), started with a dam on the river Amstel in the late 12th century, and Rotterdam began with a dam on the river Rotte ,

14364-642: The water load, and are often used to control and stabilize water flow for irrigation systems. An example of this type of dam is the now-decommissioned Red Bluff Diversion Dam on the Sacramento River near Red Bluff, California . Barrages that are built at the mouths of rivers or lagoons to prevent tidal incursions or use the tidal flow for tidal power are known as tidal barrages . Embankment dams are made of compacted earth, and are of two main types: rock-fill and earth-fill. Like concrete gravity dams, embankment dams rely on their weight to hold back

14490-581: The world is the 305 m-high (1,001 ft) Jinping-I Dam in China . As with large dams, small dams have multiple uses, such as, but not limited to, hydropower production, flood protection, and water storage. Small dams can be particularly useful on farms to capture runoff for later use, for example, during the dry season. Small scale dams have the potential to generate benefits without displacing people as well, and small, decentralised hydroelectric dams can aid rural development in developing countries. In

14616-717: The years leading up to it the U.S. government had continued to seize Lakota lands. A Ghost Dance ritual on the Northern Lakota reservation at Wounded Knee, South Dakota , led to the U.S. Army's attempt to subdue the Lakota. The dance was part of a religious movement founded by the Northern Paiute spiritual leader Wovoka that told of the return of the Messiah to relieve the suffering of Native Americans and promised that if they would live righteous lives and perform

14742-548: Was 102 m (335 ft) long at its base and 87 m (285 ft) 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 (9.9 mi) long linking

14868-677: Was a very significant moment for the rights of Native Americans and other people of color. Native Americans faced racism and prejudice for hundreds of years, and this increased after the American Civil War . Native Americans, like African Americans, were subjected to the Jim Crow Laws and segregation in the Deep South especially after they were made citizens through the Indian Citizenship Act of 1924. As

14994-715: Was an engineering wonder, and Eflatun Pinar, a Hittite dam and spring temple in Turkey, dates to the 15th and 13th centuries BC. The Kallanai Dam in South India, built in the 2nd century AD, is one of the oldest water regulating structures still in use. Roman engineers built dams with advanced techniques and materials, such as hydraulic mortar and Roman concrete, which allowed for larger structures. They introduced reservoir dams, arch-gravity dams, arch dams, buttress dams, and multiple arch buttress dams. In Iran, bridge dams were used for hydropower and water-raising mechanisms. During

15120-519: Was as follows: According to Office of Management and Budget, "American Indian or Alaska Native" refers to a person having origins in any of the original peoples of North and South America (including Central America) and who maintains tribal affiliation or community attachment. Despite generally referring to groups indigenous to the continental US and Alaska, this demographic as defined by the US Census Bureau includes all Indigenous people of

15246-560: Was built. The system included 16 reservoirs, dams 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 sometime between 1750 and 1700 BC, it was made of packed earth – triangular in cross-section, 580 m (1,900 ft) in length and originally 4 m (13 ft) high – running between two groups of rocks on either side, to which it

15372-635: Was introduced in 2000. If American Indian or Alaska Native was selected, the form requested the individual provide the name of the "enrolled or principal tribe". Censuses counted around 346,000 Native Americans in 1880 (including 33,000 in Alaska and 82,000 in Oklahoma, back then known as Indian Territory ), around 274,000 in 1890 (including 25,500 in Alaska and 64,500 in Oklahoma), 362,500 in 1930 and 366,500 in 1940, including those on and off reservations in

15498-488: Was linked by substantial stonework. Repairs were carried out during various periods, most importantly around 750 BC, and 250 years later the dam height was increased to 7 m (23 ft). After the end of the Kingdom of Saba , the dam fell under the control of the Ḥimyarites (c. 115 BC) who undertook further improvements, creating a structure 14 m (46 ft) high, with five spillways, two masonry-reinforced sluices,

15624-404: Was possibly the world's first concrete arch dam. Designed by Henry Charles Stanley in 1880 with an overflow spillway and a special water outlet, it was eventually heightened to 10 m (33 ft). In the latter half of the nineteenth century, significant advances in the scientific theory of masonry dam design were made. This transformed dam design from an art based on empirical methodology to

15750-461: Was the first French arch dam of the industrial era , and it was built by François Zola in the municipality of Aix-en-Provence to improve the supply of water after the 1832 cholera outbreak devastated the area. After royal approval was granted in 1844, the dam was constructed over the following decade. Its construction was carried out on the basis of the mathematical results of scientific stress analysis. The 75-miles dam near Warwick , Australia,

15876-634: Was the largest masonry dam in the world. The Hoover Dam is a massive concrete arch-gravity dam , constructed in the Black Canyon of the Colorado River , on the border between the US states of Arizona and Nevada between 1931 and 1936 during the Great Depression . In 1928, Congress authorized the project to build a dam that would control floods, provide irrigation water and produce hydroelectric power . The winning bid to build

#896103