The Paraná River is a river in south Central South America, running through Brazil and Argentina for some 4,880 kilometres. It is second in length only to the Amazon River among South American rivers; the name Paraná is an abbreviation of the phrase "para rehe onáva", which comes from the Tupi language and means "like the sea". It merges first with the Paraguay River and farther downstream with the Uruguay River to form the Río de la Plata and empties into the Atlantic Ocean; the first European to go up the Paraná River was the Venetian explorer Sebastian Cabot, in 1526, while working for Spain. The course is formed at the confluence of the Rio Grande rivers in southern Brazil. From the confluence the river flows in a southwestern direction for about 619 km before encountering the city of Saltos del Guaira, Paraguay; this was once the location of the Guaíra Falls (Sete Quedas waterfalls, where the Paraná fell over a series of seven cascades. This natural feature was said to rival the world-famous Iguazu Falls to the south.
The falls were flooded, however, by the construction of the Itaipu Dam, which began operating in 1984. For the next 200 km the Paraná flows southward and forms a natural boundary between Paraguay and Brazil until the confluence with the Iguazu River. Shortly upstream from this confluence, the river is dammed by the Itaipu Dam, the second largest hydroelectric power plant in the world, creating a massive, shallow reservoir behind it. After merging with the Iguazu, the Paraná becomes the natural border between Paraguay and Argentina. Overlooking the Paraná River from Encarnación, across the river, is downtown Posadas, Argentina; the river continues its general southward course for about 468 km before making a gradual turn to the west for another 820 km, encounters the Paraguay River, the largest tributary along the course of the river. Before this confluence the river passes through a second major hydroelectric project, the Yaciretá Dam, a joint project between Paraguay and Argentina; the massive reservoir formed by the project has been the source of a number of problems for people living along the river, most notably the poorer merchants and residents in the low-lying areas of Encarnación, a major city on the southern border of Paraguay.
River levels rose upon completion of the dam, flooding out large sections of the city's lower areas. From the confluence with the Paraguay River, the Paraná again turns to the south for another 820 km through Argentina, making a slow turn back to the east near the city of Rosario for the final stretch of less than 500 km before merging with the Uruguay River to form the Río de la Plata; this flows into the Atlantic Ocean. During the part of its course downstream from the city of Diamante, Entre Ríos, it splits into several arms and it forms the Paraná Delta. Together with its tributaries, the Rio Paraná forms a massive drainage basin that encompasses much of the southcentral part of South America including all of Paraguay, much of southern Brazil, northern Argentina, the southeastern part of Bolivia. If the Uruguay River is counted as a tributary to the Paraná, this watershed extends to cover most of Uruguay as well; the volume of water flowing into the Atlantic Ocean through the Río de la Plata equals the volume at the Mississippi River delta.
This watershed contains a number of large cities, including São Paulo, Buenos Aires, Asunción, Brasília, La Plata. The Paraná and its tributaries provide a source of income and of daily sustenance for fishermen who live along its banks; some of the species of fish are commercially important, they are exploited for heavy internal consumption or for export. The Parana River delta ranks as one of the world's greatest bird-watching destinations. Much of the length of the Paraná is navigable, the river serves as an important waterway linking inland cities in Argentina and Paraguay with the ocean, providing deepwater ports in some of these cities; the construction of enormous hydroelectric dams along the river's length has blocked its use as a shipping corridor to cities further upstream, but the economic impact of those dams offsets this. The Yacyretá Dam and the Itaipu Dam on the Paraguay border have made the small undeveloped nation of Paraguay the world's largest exporter of hydroelectric power.
Due to its use for oceangoing ships, measurements of the water tables extend back to 1904. The data correlates with the solar cycle; the course of the Paraná is crossed by the following bridges, beginning upstream: Tributaries of the Río de la Plata Paraná River steamers Information and a map of the Paraná's watershed "Paraná". New International Encyclopedia. 1905
La Pampa Province
La Pampa is a sparsely populated province of Argentina, located in the Pampas in the center of the country. Neighboring provinces are from the north clockwise San Luis, Córdoba, Buenos Aires, Río Negro, Neuquén and Mendoza. In 1604 Hernandarias was the first European explorer to reach the area, but it was not until the 18th century. Resistance of the local indigenous people prevented much expansion until the government of Juan Manuel de Rosas, it did not cease until Julio Roca's conquest of the desert in the 19th century. The territory was divided between the officers, they erected the first Spanish settlements; the Territorio Nacional de La Pampa Central was erected in 1884, containing the Río Negro Province and parts of other surrounding provinces. It had around 25,000 inhabitants. By 1915 there were a reflection of movement to that area. In 1945 the territory was divided and La Pampa became a province. In 1952 its constitution was written and the province was renamed after Eva Peron. In 1955 after the government changed and the Peróns went into exile, both La Pampa and Chaco, named for Juan Perón, were reverted to their original names.
There are only two major rivers in the province: the Colorado on the border with the Province of Río Negro, the Salado crossing it. The Salado's level has been dropping, as its tributaries in the Province of Mendoza are diverted for irrigation; the general aspect of the central-eastern part of the province is that of a plain tilted to the east, dissected by valleys. The surface of the plain has a calcrete crust; the valleys of La Pampa, known as the transverse valleys are NE-SW oriented, with breads of various kilometers and lengths of tens of kilometers. Some of the valleys host large fossil inland dunes. Functioning as windfunnels for sand at present these valleys are an ecotone region between the Dry and Humid Pampas. While flat the province do contains mountains like Sierra de Lihuel Calel where a variety of landforms can be observed including inselbergs, flared slopes, nubbins, tors and gnammas. Most of Sierra de Lihuel Calel is made up ignimbrite, a volcanic rock type, violently erupted by ancient volcanoes.
Being located in the Pampas, the province has a cool temperate climate. In general, the province is dominated by two different types of climates: a temperate one in the east and a semi-arid one in the west. Precipitation decreases from east to west and from north to south. Being characterized by large thermal amplitudes, the climate of the province has continental characteristics in the west where thermal amplitudes are much larger; the general atmospheric circulation is one of the most important factors that influence the climate on a regional scale. During summer, the South Atlantic High is displaced to the southeast, which brings hot and humid air masses from the north and northeast; the South Pacific High in summer is responsible for bringing cooler air masses from the southwest which when these two contrasting air masses meet lead to precipitation occurring. In contrast, winters are dry due the northward displacement of the South Atlantic high and the topographic barrier of the Andes north of 40oS which prevents frontal systems that bring precipitation from reaching the province.
Any winds from the southwest during winter bring in cold and dry weather since most of the precipitation and humidity are released in the Andes. As such, most of the precipitation occurs during summer. Mean annual temperatures in the province range between 14 to 16 °C although the thermal amplitude is large. In summer, mean temperatures in the warmest month range from 24 °C in the north and northeastern parts to 22 °C in the west and southwestern parts of the province. Temperatures tend to be cooler in the west owing to the higher altitudes. In winter, mean temperatures in the coldest month range from 8 °C in the north to 6 °C in the west and southwest; the northern parts are the warmest parts of the province. The lowest temperatures recorded range from −10 °C in the northeast to −17 °C in the southwest. One characteristic of the precipitation in the province is that most of the precipitation occurs from October to March with little precipitation during winter. Mean annual precipitation ranges from a low of 260 mm in the southwest to 820 mm in the northeast.
Precipitation decreases from northeast to southwest. Most of the precipitation is caused by frontal systems. Precipitation is variable from year to year. La Pampa, long Argentina's most economically agricultural province, produced an estimated US$3.144 billion in output in 2006, or, US$10,504 per capita. Now, the GDP per capita of the province is of US$14.000. Agriculture contributes a fourth to La Pampa's economy, the most important activity being cattle ranching, with 3,632,684 head, which takes place all over the province. Other livestock include 140,498 goats and 64,118 pigs; the Northeast, on the more fertile lands, has an important activity with wheat, maize, alfalfa and other cereals. There's a dairy industry of 300 centres of extraction and 25 cheese factories, honey production, salt extraction from salt basins. La Pampa is home to little
A flood is an overflow of water that submerges land, dry. In the sense of "flowing water", the word may be applied to the inflow of the tide. Floods are an area of study of the discipline hydrology and are of significant concern in agriculture, civil engineering and public health. Flooding may occur as an overflow of water from water bodies, such as a river, lake, or ocean, in which the water overtops or breaks levees, resulting in some of that water escaping its usual boundaries, or it may occur due to an accumulation of rainwater on saturated ground in an areal flood. While the size of a lake or other body of water will vary with seasonal changes in precipitation and snow melt, these changes in size are unlikely to be considered significant unless they flood property or drown domestic animals. Floods can occur in rivers when the flow rate exceeds the capacity of the river channel at bends or meanders in the waterway. Floods cause damage to homes and businesses if they are in the natural flood plains of rivers.
While riverine flood damage can be eliminated by moving away from rivers and other bodies of water, people have traditionally lived and worked by rivers because the land is flat and fertile and because rivers provide easy travel and access to commerce and industry. Some floods develop while others such as flash floods can develop in just a few minutes and without visible signs of rain. Additionally, floods can be local, impacting a neighborhood or community, or large, affecting entire river basins; the word "flood" comes from a word common to Germanic languages. Floods can happen on flat or low-lying areas when water is supplied by rainfall or snowmelt more than it can either infiltrate or run off; the excess accumulates in place, sometimes to hazardous depths. Surface soil can become saturated, which stops infiltration, where the water table is shallow, such as a floodplain, or from intense rain from one or a series of storms. Infiltration is slow to negligible through frozen ground, concrete, paving, or roofs.
Areal flooding begins in flat areas like floodplains and in local depressions not connected to a stream channel, because the velocity of overland flow depends on the surface slope. Endorheic basins may experience areal flooding during periods when precipitation exceeds evaporation. Floods occur in all types of river and stream channels, from the smallest ephemeral streams in humid zones to normally-dry channels in arid climates to the world's largest rivers; when overland flow occurs on tilled fields, it can result in a muddy flood where sediments are picked up by run off and carried as suspended matter or bed load. Localized flooding may be caused or exacerbated by drainage obstructions such as landslides, debris, or beaver dams. Slow-rising floods most occur in large rivers with large catchment areas; the increase in flow may be the result of sustained rainfall, rapid snow melt, monsoons, or tropical cyclones. However, large rivers may have rapid flooding events in areas with dry climate, since they may have large basins but small river channels and rainfall can be intense in smaller areas of those basins.
Rapid flooding events, including flash floods, more occur on smaller rivers, rivers with steep valleys, rivers that flow for much of their length over impermeable terrain, or normally-dry channels. The cause may be localized convective precipitation or sudden release from an upstream impoundment created behind a dam, landslide, or glacier. In one instance, a flash flood killed eight people enjoying the water on a Sunday afternoon at a popular waterfall in a narrow canyon. Without any observed rainfall, the flow rate increased from about 50 to 1,500 cubic feet per second in just one minute. Two larger floods occurred at the same site within a week, but no one was at the waterfall on those days; the deadly flood resulted from a thunderstorm over part of the drainage basin, where steep, bare rock slopes are common and the thin soil was saturated. Flash floods are the most common flood type in normally-dry channels in arid zones, known as arroyos in the southwest United States and many other names elsewhere.
In that setting, the first flood water to arrive is depleted. The leading edge of the flood thus advances more than and higher flows; as a result, the rising limb of the hydrograph becomes quicker as the flood moves downstream, until the flow rate is so great that the depletion by wetting soil becomes insignificant. Flooding in estuaries is caused by a combination of sea tidal surges caused by winds and low barometric pressure, they may be exacerbated by high upstream river flow. Coastal areas may be flooded by storm events at sea, resulting in waves over-topping defenses or in severe cases by tsunami or tropical cyclones. A storm surge, from either a tropical cyclone or an extratropical cyclone, falls within this category. Research from the NHC explains: "Storm surge is an abnormal rise of water generated by a storm and above the predicted astronomical tides. Storm surge should not be confused with storm tide, defined as the water level rise due to the combination of storm surge and the astronomical tide.
This rise in water level can cause extreme flooding in coastal areas when storm surge coincides with normal high tide, resulting in storm tides reaching up to 20 feet or more in some cases." Urban flooding is the inundation of land or property in a built environment in more densely populated areas, caused by rainfall overwhelmi
A tributary or affluent is a stream or river that flows into a larger stream or main stem river or a lake. A tributary does not flow directly into a ocean. Tributaries and the main stem river drain the surrounding drainage basin of its surface water and groundwater, leading the water out into an ocean. A confluence, where two or more bodies of water meet together refers to the joining of tributaries; the opposite to a tributary is a distributary, a river or stream that branches off from and flows away from the main stream. Distributaries are most found in river deltas. "Right tributary" and "left tributary" are terms stating the orientation of the tributary relative to the flow of the main stem river. These terms are defined from the perspective of looking downstream. In the United States, where tributaries sometimes have the same name as the river into which they feed, they are called forks; these are designated by compass direction. For example, the American River receives flow from its North and South forks.
The Chicago River's North Branch has the East and Middle Fork. Forks are sometimes left. Here, the "handedness" is from the point of view of an observer facing upstream. For instance, Steer Creek has a left tributary, called Right Fork Steer Creek. Tributaries are sometimes listed starting with those nearest to the source of the river and ending with those nearest to the mouth of the river; the Strahler Stream Order examines the arrangement of tributaries in a hierarchy of first, second and higher orders, with the first-order tributary being the least in size. For example, a second-order tributary would be the result of two or more first-order tributaries combining to form the second-order tributary. Another method is to list tributaries from mouth to source, in the form of a tree structure, stored as a tree data structure. A gallery of major river basins with tributaries Estuary
Canals, or navigations, are human-made channels, or artificial waterways, for water conveyance, or to service water transport vehicles. In most cases, the engineered works will have a series of dams and locks that create reservoirs of low speed current flow; these reservoirs are referred to as slack water levels just called levels. A canal is known as a navigation when it parallels a river and shares part of its waters and drainage basin, leverages its resources by building dams and locks to increase and lengthen its stretches of slack water levels while staying in its valley. In contrast, a canal cuts across a drainage divide atop a ridge requiring an external water source above the highest elevation. Many canals have been built at elevations towering over valleys and other water ways crossing far below. Canals with sources of water at a higher level can deliver water to a destination such as a city where water is needed; the Roman Empire's aqueducts were such water supply canals. A navigation is a series of channels that run parallel to the valley and stream bed of an unimproved river.
A navigation always shares the drainage basin of the river. A vessel uses the calm parts of the river itself as well as improvements, traversing the same changes in height. A true canal is a channel that cuts across a drainage divide, making a navigable channel connecting two different drainage basins. Most commercially important canals of the first half of the 19th century were a little of each, using rivers in long stretches, divide crossing canals in others; this is true for many canals still in use. Both navigations and canals use engineered structures to improve navigation: weirs and dams to raise river water levels to usable depths. Since they cut across drainage divides, canals are more difficult to construct and need additional improvements, like viaducts and aqueducts to bridge waters over streams and roads, ways to keep water in the channel. There are two broad types of canal: Waterways: canals and navigations used for carrying vessels transporting goods and people; these can be subdivided into two kinds:Those connecting existing lakes, other canals or seas and oceans.
Those connected in a city network: such as the Canal Grande and others of Venice Italy. Aqueducts: water supply canals that are used for the conveyance and delivery of potable water for human consumption, municipal uses, hydro power canals and agriculture irrigation. Canals were of immense importance to commerce and the development and vitality of a civilization. In 1855 the Lehigh Canal carried over 1.2 million tons of anthracite coal. The few canals still in operation in our modern age are a fraction of the numbers that once fueled and enabled economic growth, indeed were a prerequisite to further urbanization and industrialization – for the movement of bulk raw materials such as coal and ores are difficult and marginally affordable without water transport; such raw materials fueled the industrial developments and new metallurgy resulting of the spiral of increasing mechanization during 17th–20th century, leading to new research disciplines, new industries and economies of scale, raising the standard of living for any industrialized society.
The surviving canals, including most ship canals, today service bulk cargo and large ship transportation industries, whereas the once critical smaller inland waterways conceived and engineered as boat and barge canals have been supplanted and filled in, abandoned and left to deteriorate, or kept in service and staffed by state employees, where dams and locks are maintained for flood control or pleasure boating. Their replacement was gradual, beginning first in the United States in the mid-1850s where canal shipping was first augmented by began being replaced by using much faster, less geographically constrained & limited, cheaper to maintain railways. By the early 1880s, canals which had little ability to economically compete with rail transport, were off the map. In the next couple of decades, coal was diminished as the heating fuel of choice by oil, growth of coal shipments leveled off. After World War I when motor-trucks came into their own, the last small U. S. barge canals saw a steady decline in cargo ton-miles alongside many railways, the flexibility and steep slope climbing capability of lorries taking over cargo hauling as road networks were improved, which had the freedom to make deliveries well away from rail lined road beds or ditches in the dirt which couldn't operate in the winter.
Canals are built in one of three ways, or a combination of the three, depending on available water and available path: Human made streamsA canal can be created where no stream presently exists. Either the body of the canal is dug or the sides of the canal are created by making dykes or levees by piling dirt, concrete or other building materials; the finished shape of the canal as seen in cross section is known as the canal prism. The water for the canal must be provided like streams or reservoirs. Where the new waterway must change elevation engineering works like locks, lifts or elevators are constructed to raise and lower vessels. Examples include canals that connect valleys over a higher body of land, like Canal du Midi, Canal de Briare and the Panama Canal. A canal can be constructed by dredging a channel in the bottom of an existing lake; when the channel is complete, the lake is drained and the channel becom
Samborombón Bay is a bay on the coast of Buenos Aires Province, Argentina. Located at the Río de la Plata's mouth on the Argentine Sea, it begins about 160 kilometres southeast of Buenos Aires and is about 135 kilometres wide; the bay is thought to have been named in 1520 by members of Ferdinand Magellan's expedition, who attributed its nearly semicircular shape to the detachment of legendary Saint Brendan's Island from the South American mainland. The Samborombón River and the town of Samborombón share the bay's name. Samborombón Bay is located at the mouth of the Río de la Plata, stretching from Punta Piedras in the north to Punta Rasa in the south, where Cape San Antonio begins. Depending on the boundaries used, the bay can be considered an estuary stretch of the Río de la Plata or a large bay of the Argentine Sea; the bay receives inflow from the Southern Salado River, the Samborombón River, other smaller streams, as well as numerous artificial canals constructed to drain eastern Buenos Aires Province.
It experiences a substantial flow of water coming out from the Río de la Plata into the Argentine Sea. Samborombón Bay exhibits an unusually high density of shorebird species, many of which use the bay as a stopping point in their seasonal migrations, it serves as an important nursery habitat for fish species in the Río de la Plata estuary system. The bay and the adjoining coastal region are included in a number of protected areas because of the well preserved Pampas grassland and wetland ecosystems that characterize the area; the Province of Buenos Aires' Provincial Body for Sustainable Development has designated the central portion of the coast as the Samborombón Bay Provincial Nature Reserve because of its importance as a wildlife refuge. The bay is designated as a Western Hemisphere Shorebird Reserve Network Site of International Importance, as well as a Ramsar Wetland of International Importance, reflecting its significance as a habitat for the buff-breasted sandpiper and other threatened species.
The southern shore includes home to a population of rare Pampas deer. The Samborombón Bay coast is known for its excellent sport fishing in the waters near Punta Rasa and the town of General Lavalle, where large saltwater species such as black drum are abundant. Map of Samborombón Bay and its various protected areas from the Argentine National Parks Administration
A river is a natural flowing watercourse freshwater, flowing towards an ocean, lake or another river. In some cases a river flows into the ground and becomes dry at the end of its course without reaching another body of water. Small rivers can be referred to using names such as stream, brook and rill. There are no official definitions for the generic term river as applied to geographic features, although in some countries or communities a stream is defined by its size. Many names for small rivers are specific to geographic location. Sometimes a river is defined as being larger than a creek, but not always: the language is vague. Rivers are part of the hydrological cycle. Potamology is the scientific study of rivers, while limnology is the study of inland waters in general. Most of the major cities of the world are situated on the banks of rivers, as they are, or were, used as a source of water, for obtaining food, for transport, as borders, as a defensive measure, as a source of hydropower to drive machinery, for bathing, as a means of disposing of waste.
A river begins at a source, follows a path called a course, ends at a mouth or mouths. The water in a river is confined to a channel, made up of a stream bed between banks. In larger rivers there is also a wider floodplain shaped by flood-waters over-topping the channel. Floodplains may be wide in relation to the size of the river channel; this distinction between river channel and floodplain can be blurred in urban areas where the floodplain of a river channel can become developed by housing and industry. Rivers can flow down mountains, through valleys or along plains, can create canyons or gorges; the term upriver refers to the direction towards the source of the river, i.e. against the direction of flow. The term downriver describes the direction towards the mouth of the river, in which the current flows; the term left bank refers to the left bank in the direction of right bank to the right. The river channel contains a single stream of water, but some rivers flow as several interconnecting streams of water, producing a braided river.
Extensive braided rivers are now found in only a few regions worldwide, such as the South Island of New Zealand. They occur on peneplains and some of the larger river deltas. Anastamosing rivers are quite rare, they have multiple sinuous channels carrying large volumes of sediment. There are rare cases of river bifurcation in which a river divides and the resultant flows ending in different seas. An example is the bifurcation of Nerodime River in Kosovo. A river flowing in its channel is a source of energy which acts on the river channel to change its shape and form. In 1757, the German hydrologist Albert Brahms empirically observed that the submerged weight of objects that may be carried away by a river is proportional to the sixth power of the river flow speed; this formulation is sometimes called Airy's law. Thus, if the speed of flow is doubled, the flow would dislodge objects with 64 times as much submerged weight. In mountainous torrential zones this can be seen as erosion channels through hard rocks and the creation of sands and gravels from the destruction of larger rocks.
A river valley, created from a U-shaped glaciated valley, can easily be identified by the V-shaped channel that it has carved. In the middle reaches where a river flows over flatter land, meanders may form through erosion of the river banks and deposition on the inside of bends. Sometimes the river will cut off a loop, shortening the channel and forming an oxbow lake or billabong. Rivers that carry large amounts of sediment may develop conspicuous deltas at their mouths. Rivers whose mouths are in saline tidal waters may form estuaries. Throughout the course of the river, the total volume of water transported downstream will be a combination of the free water flow together with a substantial volume flowing through sub-surface rocks and gravels that underlie the river and its floodplain. For many rivers in large valleys, this unseen component of flow may exceed the visible flow. Most but not all rivers flow on the surface. Subterranean rivers flow underground in caverns; such rivers are found in regions with limestone geologic formations.
Subglacial streams are the braided rivers that flow at the beds of glaciers and ice sheets, permitting meltwater to be discharged at the front of the glacier. Because of the gradient in pressure due to the overlying weight of the glacier, such streams can flow uphill. An intermittent river only flows and can be dry for several years at a time; these rivers are found in regions with limited or variable rainfall, or can occur because of geologic conditions such as a permeable river bed. Some ephemeral rivers flow during the summer months but not in the winter; such rivers are fed from chalk aquifers which recharge from winter rainfall. In England these rivers are called bournes and give their name to places such as Bournemouth and Eastbourne. In humid regions, the location where flow begins in the smallest tributary streams moves upstream in response to precipitation and downstream in its absence or when active summer vegetation diverts water for evapotrans