Guayanan Highlands moist forests
The Guayanan Highlands moist forests is an ecoregion in the south of Venezuela and the north of Brazil and in Guyana, French Guiana. It is in the Amazon biome, it encompasses an upland region with diverse fauna and flora, which contains dramatic tepuis, or sandstone table mountains. The region has been inaccessible in the past and is fairly intact, apart from the north and northeast where large scale agriculture and mining operations are encroaching on the ecosystem. New roads are opening the interior to logging, planned dams will have a drastic impact on the riparian zones; the ecoregion includes parts of southern Venezuela and southern Guyana and northern Brazil, with scattered portions in Suriname and French Guiana. It extends into eastern Colombia, it has a total area of 33,747,545 hectares. The ecoregion lies on the Guiana Shield, an ancient upland area between the Amazon and Orinoco basins, it is surrounded by lowland forest. All areas of the ecoregion contains enclaves of the Pantepuis ecoregion on the tops of table mountains.
Most areas of the ecoregion in the east are surrounded by the Guianan moist forests ecoregion, most areas in the west are surrounded by the Guianan piedmont and lowland moist forests ecoregion. Sections of the ecoregion in the east border the Uatuma-Trombetas moist forests to the south; the central part of the ecoregion surrounds the northern part of the largest section of the Guianan savanna ecoregion The southwestern part of the ecoregion rises above the Negro-Branco moist forests ecoregion. The Guayanan Highlands moist forests and the Tepuis together make up the Guayanan Highlands Forests Global 200 ecoregion; the terrain is rugged, with elevations in the ecoregion from 500 to 1,500 metres above sea level. Taller table mountains in the region rise to elevations of 3,000 metres and host the Tepui ecoregion; the Guayanan Highlands ecoregion is an "island" of higher land surrounded by lower grasslands and forests. Most of the land drains into the Orinoco through the Ventuari, Caroní, Paragua and Caura rivers in Venezuela.
In the south, it is drained by the Branco rivers in Brazil into the Amazon. The upland terraces and mountains consist of quartzitic or sandstone rocks, with granitic rock in some areas; the lowland plains are recent flooded by lakes or by the sea. Most of the landscape is forest-covered rolling floodplains; the undulating peneplains between the Caura and Paragua rivers hold low hills up to 500 metres high. There are scattered upland areas of undulating plains, rounded hills, low mountains and Tepuis up to 1,500 metres high, the lower slopes of the higher tepuis. Soils are sandy and low in nutrients; the Guayanan Highlands moist forests ecoregion is in the neotropic ecozone and the tropical and subtropical moist broadleaf forests biome. The Köppen climate classification is "Am": monsoonal. Temperatures vary little throughout the year. Yearly average temperatures range from a minimum of 18 °C to a maximum of 29 °C, with a mean of 23 °C. Annual rainfall varies but in some areas averages 3,750 millimetres.
Monthly rainfall is lowest in highest in July at 537 millimetres. There are various habitats including large areas of tall primary rainforest, open savannas and gallery forests; the peneplains hold evergreen forests with dense canopies of 30 to 40 metres with emergent trees in the Calophyllum, Manilkara, Inga, Copaifera and Dipteryx genera. Common trees on the plains include Micropholis melinoniana, Dacryodes species, Euterpe precatoria and Quassia cedron. There are fewer emergent trees in the hilly areas, where tree species include Newtonia suaveolens, Couratari guanensis, Alexa species, Euterpe precatoria and Micrandra minor; the seasonally flooded forests along the rivers have similar formations of flora to the Amazon region. Common tree species on the upper Orinoco include Combretum frangulifolium, Gustavia augusta, Pterocarpus species, Etaballia dubia, Albizia corymbosa, Spondias mombin, Mabea nitida, Eschweilera tenuifolia, Astrocaryum aculeatum and Inga species. Floodplain trees include Caryocar microcarpum, Caraipa densifolia, Macrolobium acaciaefolium, Abuta grandfolia and Panopsis rubescens.
209 species of mammals have been recorded, including jaguar, South American tapir, white-lipped peccary, collared peccary, brocket deer, white-eared opossum, lutrine opossum, Robinson's mouse opossum, Davy's naked-backed bat, Fernandez's sword-nosed bat, highland yellow-shouldered bat, eastern lowland olingo, fiery squirrel, Guyanan spiny rat and Orinoco agouti. Endangered mammals include Fernandez's sword-nosed bat and giant otter. Snakes include palm pit-vipers, coral snakes, boa constrictors and bushmasters. There are tegus lizards. Endangered amphibians include the demonic poison frog.631 species of birds have been recorded, including white-cheeked pintail, aplomado falcon, brown-throated parakeet, pavon
Venezuela the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and a large number of small islands and islets in the Caribbean Sea. The capital and largest urban agglomeration is the city of Caracas, it has a territorial extension of 916,445 km2. The continental territory is bordered on the north by the Caribbean Sea and the Atlantic Ocean, on the west by Colombia, Brazil on the south and Tobago to the north-east and on the east by Guyana. With this last country, the Venezuelan government maintains a claim for Guayana Esequiba over an area of 159,542 km2. For its maritime areas, it exercises sovereignty over 71,295 km2 of territorial waters, 22,224 km2 in its contiguous zone, 471,507 km2 of the Caribbean Sea and the Atlantic Ocean under the concept of exclusive economic zone, 99,889 km2 of continental shelf; this marine area borders those of 13 states. The country has high biodiversity and is ranked seventh in the world's list of nations with the most number of species.
There are habitats ranging from the Andes Mountains in the west to the Amazon basin rain-forest in the south via extensive llanos plains, the Caribbean coast and the Orinoco River Delta in the east. The territory now known as Venezuela was colonized by Spain in 1522 amid resistance from indigenous peoples. In 1811, it became one of the first Spanish-American territories to declare independence, not securely established until 1821, when Venezuela was a department of the federal republic of Gran Colombia, it gained full independence as a country in 1830. During the 19th century, Venezuela suffered political turmoil and autocracy, remaining dominated by regional caudillos until the mid-20th century. Since 1958, the country has had a series of democratic governments. Economic shocks in the 1980s and 1990s led to several political crises, including the deadly Caracazo riots of 1989, two attempted coups in 1992, the impeachment of President Carlos Andrés Pérez for embezzlement of public funds in 1993.
A collapse in confidence in the existing parties saw the 1998 election of former coup-involved career officer Hugo Chávez and the launch of the Bolivarian Revolution. The revolution began with a 1999 Constituent Assembly, where a new Constitution of Venezuela was written; this new constitution changed the name of the country to Bolivarian Republic of Venezuela. The sovereign state is a federal presidential republic consisting of 23 states, the Capital District, federal dependencies. Venezuela claims all Guyanese territory west of the Essequibo River, a 159,500-square-kilometre tract dubbed Guayana Esequiba or the Zona en Reclamación. Venezuela is among the most urbanized countries in Latin America. Oil was discovered in the early 20th century, today, Venezuela has the world's largest known oil reserves and has been one of the world's leading exporters of oil; the country was an underdeveloped exporter of agricultural commodities such as coffee and cocoa, but oil came to dominate exports and government revenues.
The 1980s oil glut led to a long-running economic crisis. Inflation peaked at 100% in 1996 and poverty rates rose to 66% in 1995 as per capita GDP fell to the same level as 1963, down a third from its 1978 peak; the recovery of oil prices in the early 2000s gave. The Venezuelan government under Hugo Chávez established populist social welfare policies that boosted the Venezuelan economy and increased social spending, temporarily reducing economic inequality and poverty in the early years of the regime. However, such populist policies became inadequate, causing the nation's collapse as their excesses—including a uniquely extreme fossil fuel subsidy—are blamed for destabilizing the nation's economy; the destabilized economy led to a crisis in Bolivarian Venezuela, resulting in hyperinflation, an economic depression, shortages of basic goods and drastic increases in unemployment, disease, child mortality and crime. These factors have precipitated the Venezuelan Migrant Crisis where more than three million people have fled the country.
By 2017, Venezuela was declared to be in default regarding debt payments by credit rating agencies. In 2018, the country's economic policies led to extreme hyperinflation, with estimates expecting an inflation rate of 1,370,000% by the end of the year. Venezuela is a charter member of the UN, OAS, UNASUR, ALBA, Mercosur, LAIA and OEI. According to the most popular and accepted version, in 1499, an expedition led by Alonso de Ojeda visited the Venezuelan coast; the stilt houses in the area of Lake Maracaibo reminded the Italian navigator, Amerigo Vespucci, of the city of Venice, Italy, so he named the region Veneziola, or "Little Venice". The Spanish version of Veneziola is Venezuela. Martín Fernández de Enciso, a member of the Vespucci and Ojeda crew, gave a different account. In his work Summa de geografía, he states that the crew found indigenous people who called themselves the Veneciuela. Thus, the name "Venezuela" may have evolved from the native word; the official name was Estado de Venezuela, República de Venezuela, Estados Unidos de Venezuela, a
Alfred Russel Wallace
Alfred Russel Wallace was a British naturalist, geographer and biologist. He is best known for independently conceiving the theory of evolution through natural selection; this prompted Darwin to publish his own ideas in On the Origin of Species. Wallace did extensive fieldwork, first in the Amazon River basin and in the Malay Archipelago, where he identified the faunal divide now termed the Wallace Line, which separates the Indonesian archipelago into two distinct parts: a western portion in which the animals are of Asian origin, an eastern portion where the fauna reflect Australasia, he was considered the 19th century's leading expert on the geographical distribution of animal species and is sometimes called the "father of biogeography". Wallace was one of the leading evolutionary thinkers of the 19th century and made many other contributions to the development of evolutionary theory besides being co-discoverer of natural selection; these included the concept of warning colouration in animals, the Wallace effect, a hypothesis on how natural selection could contribute to speciation by encouraging the development of barriers against hybridisation.
Wallace's 1904 book Man's Place in the Universe was the first serious attempt by a biologist to evaluate the likelihood of life on other planets. He was one of the first scientists to write a serious exploration of the subject of whether there was life on Mars. Wallace was attracted to unconventional ideas, his advocacy of spiritualism and his belief in a non-material origin for the higher mental faculties of humans strained his relationship with some members of the scientific establishment. Aside from scientific work, he was a social activist, critical of what he considered to be an unjust social and economic system in 19th-century Britain, his interest in natural history resulted in his being one of the first prominent scientists to raise concerns over the environmental impact of human activity. He was a prolific author who wrote on both scientific and social issues. Since its publication in 1869 it has never been out of print. Wallace had financial difficulties throughout much of his life, his Amazon and Far Eastern trips were supported by the sale of specimens he collected and, after he lost most of the considerable money he made from those sales in unsuccessful investments, he had to support himself from the publications he produced.
Unlike some of his contemporaries in the British scientific community, such as Darwin and Charles Lyell, he had no family wealth to fall back on, he was unsuccessful in finding a long-term salaried position, receiving no regular income until he was awarded a small government pension, through Darwin's efforts, in 1881. Alfred Wallace was born in the Welsh village near Usk, Monmouthshire, he was the eighth of nine children of Mary Anne Greenell. Mary Anne was English, his family, like many Wallaces, claimed a connection to William Wallace, a leader of Scottish forces during the Wars of Scottish Independence in the 13th century. Thomas Wallace never practised law, he owned some income-generating property, but bad investments and failed business ventures resulted in a steady deterioration of the family's financial position. His mother was from a middle-class English family from Hertford, north of London; when Wallace was five years old, his family moved to Hertford. There he attended Hertford Grammar School until financial difficulties forced his family to withdraw him in 1836, when he was aged 14.
Wallace moved to London to board with his older brother John, a 19-year-old apprentice builder. This was a stopgap measure until William, his oldest brother, was ready to take him on as an apprentice surveyor. While in London, Alfred attended lectures and read books at the London Mechanics Institute. Here he was exposed to the radical political ideas of the Welsh social reformer Robert Owen and of Thomas Paine, he left London in 1837 to work as his apprentice for six years. At the end of 1839, they moved to Kington, near the Welsh border, before settling at Neath in Glamorgan in Wales. Between 1840 and 1843, Wallace did land surveying work in the countryside of the west of England and Wales. By the end of 1843, William's business had declined due to difficult economic conditions, Wallace, at the age of 20, left in January. One result of Wallace's early travels is a modern controversy about his nationality. Since Wallace was born in Monmouthshire, some sources have considered him to be Welsh. However, some historians have questioned this because neither of his parents was Welsh, his family only lived in Monmouthshire, the Welsh people Wallace knew in his childhood considered him to be English, because Wallace himself referred to himself as English rather than Welsh.
One Wallace scholar has stated that the most reasonable interpretation is therefore that he was an Englishman born in Wales. After a brief period of unemployment, he was hired as a master at the Collegiate School in Leicester to teach drawing and surveying. Wallace spent many hours at the library in Leicester: he read An Essay on the Principle of Population by Thomas Robert Malthus, one evening he met the entomologist Henry Bates. Bates was 19 years old, in 1843 he had published a paper on beetles in the
Food and Agriculture Organization
The Food and Agriculture Organization of the United Nations is a specialized agency of the United Nations that leads international efforts to defeat hunger. Serving both developed and developing countries, FAO acts as a neutral forum where all nations meet as equals to negotiate arguments and debate policy. FAO is a source of knowledge and information, helps developing countries in transition modernize and improve agriculture and fisheries practices, ensuring good nutrition and food security for all, its Latin motto, fiat panis, translates as "let there be bread". As of August 2018, The FAO has 197 member states, including the European Union and The Cook Islands, the Faroe Islands and Tokelau, which are associate members; the idea of an international organization for food and agriculture emerged in the late 19th and early 20th century advanced by the US agriculturalist and activist David Lubin. In May–June 1905, an international conference was held in Rome, which led to the creation of the International Institute of Agriculture by the King of Italy Victor Emmanuel III.
In 1943, the United States President Franklin D. Roosevelt called a United Nations Conference on Food and Agriculture. Representatives from forty-four governments gathered at The Homestead Resort in Hot Springs, Virginia, US, from 18 May to 3 June, they committed themselves to founding a permanent organization for food and agriculture, which happened in Quebec City, Canada, on 16 October 1945 with the conclusion of the Constitution of the Food and Agriculture Organization. The First Session of the FAO Conference was held in the Château Frontenac in Quebec City from 16 October to 1 November 1945. World War II ended the International Agricultural Institute, though it was only dissolved by resolution of its Permanent Committee on 27 February 1948, its functions were transferred to the established FAO. From the late 1940s on, FAO attempted to make its mark within the emerging UN system, focusing on supporting agricultural and nutrition research and providing technical assistance to member countries to boost production in agriculture and forestry.
During the 1950s and 1960s, FAO partnered with many different international organizations in development projects. In 1951, FAO's headquarters were moved from DC, United States, to Rome, Italy; the agency is directed by the Conference of Member Nations, which meets every two years to review the work carried out by the organization and to Work and Budget for the next two-year period. The Conference elects a council of 49 member states that acts as an interim governing body, the Director-General, that heads the agency. FAO is composed of eight departments: Agriculture and Consumer Protection, Biodiversity and Water Department and Social Development and Aquaculture, Corporate Services and Technical Cooperation and Programme Management. Beginning in 1994, FAO underwent the most significant restructuring since its founding, to decentralize operations, streamline procedures and reduce costs; as a result, savings of about US$50 million, €35 million a year were realized. FAO's Regular Programme budget is funded by its members, through contributions set at the FAO Conference.
This budget covers core technical work and partnerships including the Technical Cooperation Programme, knowledge exchange and advocacy, direction and administration and security. The total FAO Budget planned for 2016–2017 is USD 2.6 billion. The voluntary contributions provided by members and other partners support mechanical and emergency assistance to governments for defined purposes linked to the results framework, as well as direct support to FAO's core work; the voluntary contributions are expected to reach US$1.6 billion in 2016–2017. This overall budget covers core technical work and partnerships, leading to Food and Agriculture Outcomes at 71 per cent; the world headquarters are located in Rome, in the former seat of the Department of Italian East Africa. One of the most notable features of the building was the Axum Obelisk which stood in front of the agency seat, although just outside the territory allocated to FAO by the Italian Government, it was taken from Ethiopia by Benito Mussolini's troops in 1937 as a war chest, returned on 18 April 2005.
Regional Office for Africa, in Accra, Ghana Regional Office for Asia and the Pacific, in Bangkok, Thailand Regional Office for Europe and Central Asia, in Budapest, Hungary Regional Office for Latin America and the Caribbean, in Santiago, Chile Regional Office for the Near East, in Cairo, Egypt Sub-regional Office for Central Africa, in Libreville, Gabon Sub-regional Office for Central Asia, in Ankara, Turkey Sub-regional Office for Eastern Africa, in Addis Ababa, Ethiopia Sub-regional Office for Mesoamerica, in Panama City, Panama Sub-regional Office for North Africa, in Tunis, Tunisia Sub-regional Office for Southern Africa and East Africa, in Harare, Zimbabwe Sub-regional Office for the Caribbean, in Bridgetown, Barbados Sub-regional Office for the Gulf Cooperation Council States and Yemen, Abu Dhabi Sub-regional Office for the Pacific Islands, in Apia, Samoa Liaison Office for North America, in Washington, DC Liaison Office with J
Boa Vista, Roraima
Boa Vista is the capital of the Brazilian state of Roraima. Situated on the western bank of the Branco River, the city lies 220 km from Brazil's border with Venezuela, it is the only Brazilian state capital located north of the equator. Boa Vista is the most populous municipality in the state of Roraima. Commerce occurs with Manaus, the capital of the State of Amazonas. Business takes place between Boa Vista and with the cities of Lethem, in Guyana and Santa Elena de Uairén, in Venezuela; these two foreign cities are the only major cities that can be accessed from Boa Vista by road, although roads connect other smaller state municipalities with the capital city. Travel by airplane is the only means of transportation with other regions of the country; as a modern city, Boa Vista stands out among the other capitals of the North Region of Brazil as it is a planned city with a radial plan. It was planned by the architect Darci Aleixo Derenusson who based his design for the city on one, similar to that of Paris, France.
The city was built under the direction of the first governor of Roraima. The municipality of Boa Vista formed the first urban area of the state of Roraima; the São Joaquim Fort, founded in 1775, is located about 32 km from the capital and is considered to be of great importance to the region. The city was created on July 1890 as Boa Vista do Rio Branco, it was founded by Augusto Villeroy. The first mayor was João Capistrano da Silva Mota known as Coronel Mota. After the mayor, two councillors were appointed. In 1943, during the middle of World War II, Boa Vista became the capital of the created Federal Territory of Rio Branco; the territory grew from mining operations in the area. The Federal Territory of Rio Branco was elevated to statehood being renamed as "Roraima". Machine-based mining was prohibited, which ended up hindering the economy of the state and the municipality. In the 2010s, the crisis in Venezuela led to the population swelling by around 50,000 Venezuelan immigrants. Boa Vista experiences a tropical savanna climate, with a hot, humid wet season and a warm dry season.
Being the only major Brazilian city north of the equator, the wettest and driest months in Boa Vista are the reverse of the rest of the Amazonian region of Brazil, with a hot, rainy period from April to November and a warm, dry period from December to March. Temperatures fluctuations are unsubstantial throughout the year; the Maracá Ecological Station was established by presidential decree on 2 June 1981. The station consists of the island of Maracá between the Santa Rosa and Maracá branches of the Uraricoera River in the municipality of Boa Vista, has an area of 101,312 hectares; the protected area was established with the purpose of preserving a representative sample of the Amazon ecosystem. The GDP of the city was R$2,265,603,000; the per capita income of the city was R$9,366. Portuguese is the official national language, the primary language taught in schools, but English and Spanish are part of the official high school curriculum. Educational institutions include: Universidade Federal de Roraima.
Anaua Park, a major recreational park is located in Boa Vista. It is the biggest park in the north region of Brazil, it has a square, a lake and a cart-racing facility. Taumanam is a small artificial beach on Rio Branco, it has several stores and snack bars and was created in 2005. The Ayrton Senna complex is the most visited tourist attraction in Boa Vista, it consists of Ayrton Senna, Velia Coutinho, Praça das Águas, Millennium Portal, Praça das Artes. Festa Junina was introduced to Northeastern Brazil by the Portuguese for whom St John's day, on the 24th of June, is one of the oldest and most popular celebrations of the year; the festivities traditionally begin after the 12th of June, on the eve of St Anthony's day, last until the 29th, Saint Peter's day. During these fifteen days, there are bonfires and folk dancing in the streets. Once a rural celebration, today, in Brazil, it is now a city festival; the Civic Center, built in the form of an opened fan, starts from the banks of the Rio Branco.
This design was created by the engineer Darci Aleixo Deregusson during Ene Garcez's government, the first of its kind in Roraima. From the Civic Center runs a system of 16 avenues, with inspiration drawn from Paris, Belo Horizonte, Goiânia, Brazil. In this square are the head offices of the Executive and Legislative branches of the state government. Other buildings of significance are the Palace of Culture, the Amazônia Bank, the Ministry of Education, a cathedral; the civic center showcases a monument to the miners who were the first inhabitants of this land. Indigenous people were the only inhabitants of Boa Vista. Boa Vista had the highest growth rate of any Brazilian capital in the 1970s
Whitewater river (river type)
A whitewater river is classified based on its chemistry and water colour. Whitewater rivers have high levels of suspended sediments, giving the water a pH, near-neutral, a high electric conductivity and a pale muddy, café au lait-like colour. Whitewater rivers are important to local fisheries; the major seasonal Amazonian floodplains known as várzea receive their water from them. The best-known whitewater rivers are Amazonian and have their source in the Andes, but there are whitewater rivers elsewhere in South America and in other continents. Amazonian rivers fall into three main categories: whitewater and clearwater; this classification system was first proposed by Alfred Russel Wallace in 1853 based on water colour, but the types were more defined according to chemistry and physics by Harald Sioli from the 1950s to the 1980s. Although many Amazonian rivers fall into one of these categories, others show a mix of characteristics and may vary depending on season and flood levels; the best-known whitewater rivers have their source in the Andes.
The main rivers that are considered whitewater are Solimões–Amazon, Caquetá–Japurá, Marañón, Javary, Juruá, Purus, Madre de Dios, Madeira. Although the Branco River traditionally is considered whitewater, it has a number of characteristics that do not fit into the classification and some refer to it as clearwater. Outside the Amazon, a small number of South American rivers are considered whitewater, most notably certain tributaries of the Orinoco such as the Guaviare and Apure Rivers, of the Paraná—Paraguay such as the Bermejo and Salado Rivers, which have their source in the Andes. Outside South America, this system of classification is not used, but there are several rivers with whitewater characteristics. In Africa, these include the Niger main stem and its floodplain, Nile, the middle and lower Zambezi, the Cross, Mungo and Wouri rivers. In Asia, examples are the Mekong mainstream, several upland streams in large river basins in the southern and southeastern part of the continent. In Europe, sections of the Danube have whitewater characteristics.
In South America, most whitewater rivers originate in the Andes where they collect high levels of nutrient-rich sediments, notably illite and montmorillonite. They have a near-neutral pH, high levels of dissolved solids, high electric conductivity; the water is turbid, with a low visibility, between 20 and 60 cm. In the main stem of the Amazon River, about 82% of the total suspended solids and 90–95% of the suspended load of sediments originate from the Andes. Along their course, whitewater rivers become diluted due to the inflow of black- and clearwater tributaries. For example, the Rio Negro, the largest blackwater tributary, accounts for 14% of the total Amazon basin water and Tapajós, the largest clearwater tributary, accounts for 6%. Although the Amazon River is whitewater throughout its course, the electric conductivity is 120–200 μS/cm in the Andes, but by the time it reaches Santarém, it has fallen to 40-70 μS/cm. At high elevations in the Andes near the headwater, the pH of whitewater rivers can be above 8.
In some parts of the Amazon where the rivers are not whitewater, "pseudo-whitewater" exists because of soil erosion from human activities. The difference in chemistry and visibility between the various black and clearwater rivers result in distinct differences in flora and fauna. Although there is considerable overlap in the fauna found in the different river types, there are many species found only in one of them. Many blackwater and clearwater species are restricted to small parts of the Amazon, as different blackwater and clearwater systems are separated by large whitewater sections; these "barriers" are considered a main force in allopatric speciation in the Amazon basin. As in South America, distinct differences between species in black- and whitewater can be seen in Asia and Africa. For example, the fish fauna in African whitewater rivers tend to be dominated by cyprinids and elephantfish, whereas blackwater rivers have more characiforms and cichlids; the high nutrient levels in whitewater rivers allow high levels of periphyton, but the water turbidity restricts light, thereby limiting photosynthetic processes, which are necessary to algae and submerged macrophytes, to the uppermost part of the water column.
The periphyton equals the production level in temperate eutrophic lakes. Bacterial abundance and production rates are equal in whitewater and blackwater rivers, but both vary with water level and productions are higher during the high-water season; the major seasonal Amazonian floodplains known as várzea receive their water from whitewater rivers and are home to many animals and plants. In the Brazilian Amazon, várzea covers 200,000 km2, equalling 4% of the entire area. In addition to forests and woodlands with trees and other plants that are seasonally covered by water, about one-third of this floodplain's area is covered by large floating meadows; these floating meadows are home to the richest Amazonian community of aquatic invertebrates and important to fish species that visit during the flood season for feeding or breeding (a lower number of fish species live in the habita
In geography, a confluence occurs where two or more flowing bodies of water join together to form a single channel. A confluence can occur in several configurations: at the point where a tributary joins a larger river. Confluences are studied in a variety of sciences. Hydrology studies the characteristic flow patterns of confluences and how they give rise to patterns of erosion and scour pools; the water flows and their consequences are studied with mathematical models. Confluences are relevant to the distribution of living organisms as well; the United States Geological Survey gives an example: "chemical changes occur when a stream contaminated with acid mine drainage combines with a stream with near-neutral pH water. According to Lynch, "the color of each river is determined by many things: type and amount of vegetation in the watershed, geological properties, dissolved chemicals and biologic content – algae." Lynch notes that color differences can persist for miles downstream before they blend completely.
Hydrodynamic behaviour of flow in a confluence can be divided into six distinct features which are called confluence flow zones. These include Stagnation zone Flow deflection zone Flow separation zone / recirculation zone Maximum velocity zone Flow recovery zone Shear layers Since rivers serve as political boundaries, confluences sometimes demarcate three abutting political entities, such as nations, states, or provinces, forming a tripoint. Various examples are found in the list below. A number of major cities, such as Chongqing, St. Louis, Khartoum, arose at confluences. Within a city, a confluence forms a visually prominent point, so that confluences are sometimes chosen as the site of prominent public buildings or monuments, as in Koblenz and Winnipeg. Cities often build parks at confluences, sometimes as projects of municipal improvement, as at Portland and Pittsburgh. In other cases, a confluence is an industrial site, as in Mannheim. A confluence lies in the shared floodplain of the two rivers and nothing is built on it, for example at Manaus, described below.
One other way that confluences may be employed by humans is as a sacred place in a religion. Rogers suggests that for the ancient peoples of the Iron Age in northwest Europe, watery locations were sacred sources and confluences. Pre-Christian Slavic peoples chose confluences as the sites for fortified triangular temples, where they practiced human sacrifice and other sacred rites. In Hinduism, the confluence of two sacred rivers is a pilgrimage site for ritual bathing. In Pittsburgh, a number of adherents to Mayanism consider their city's confluence to be sacred. At Lokoja, the Benue River flows into the Niger. At Kazungula in Zambia, the Chobe River flows into the Zambezi; the confluence defines the tripoint of Zambia and Namibia. The land border between Botswana and Zimbabwe to the east reaches the Zambezi at this confluence, so there is a second tripoint only 150 meters downstream from the first. See Kazungula and Quadripoint, Gallery below for image; the Sudanese capital of Khartoum is located at the confluence of the White Nile and the Blue Nile, the beginning of the Nile.
82 km north of Basra in Iraq at the town of Al-Qurnah is the confluence of the rivers Tigris and Euphrates, forming the Shatt al-Arab. At Devprayag in India, the Ganges River originates at the confluence of the Bhagirathi and the Alaknanda. Near Allahabad, the Yamuna flows into the Ganges. In Hinduism, this is a pilgrimage site for ritual bathing. In Hindu belief the site is held to be a triple confluence, the third river being the metaphysical Sarasvati. Kuala Lumpur, the capital of Malaysia, is where the Gombak River flows into the Klang River at the site of the Jamek Mosque; the Kolam Biru, a pool with elaborate fountains, has been installed at the apex of the confluence. The Nam Khan River flows into the Mekong at Luang Prabang in Laos; the Jialing flows into the Yangtze at Chongqing in China. The confluence forms a focal point in the city, marked by Chaotianmen Square, built in 1998. In the Far East, the Amur forms the international boundary between Russia; the Ussuri, which demarcates the border, flows into the Amur at a point midway between Fuyuan in China and Khabarovsk in Russia.
The apex of the confluence is located in a rural area, part of China, where a commemorative park, Dongji Square, has been built.