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95-551: As extensive floodplain and bog landscape, the Spree Forest was designated a biosphere reserve by UNESCO in 1991, called Biosphärenreservat Spreewald ( biosferowy rezerwat Błota ). It is known for its traditional irrigation system, consisting of more than 200 small canals (called Fließe ; total length: 1,300 kilometres or 810 miles) within the 484-square-kilometre (187 sq mi) area, for its unique flora and fauna , and for its traditional flat-bottomed boats ,

190-433: A Turkish officer, Selim Bimbashi, were made between 1839 and 1842, and two got to the point about 30 kilometres (20 miles) beyond the present port of Juba , where the country rises and rapids make navigation very difficult. Lake Victoria was first sighted by Europeans in 1858 when British explorer John Hanning Speke reached its southern shore while traveling with Richard Francis Burton to explore central Africa and locate

285-767: A distance of 20 days' journey till it reaches the nearest Ethiopians." Modern exploration of the Nile basin began with the conquest of the northern and central Sudan by the Ottoman viceroy of Egypt, Muhammad Ali , and his sons from 1821 onward. As a result of this, the Blue Nile was known as far as its exit from the Ethiopian foothills and the White Nile as far as the mouth of the Sobat River. Three expeditions under

380-468: A factor of 15 at Aswan. Peak flows of over 8,212 m /s (290,000 cu ft/s) occurred during late August and early September, and minimum flows of about 552 m /s (19,500 cu ft/s) occurred during late April and early May. The Bahr al Ghazal and the Sobat River are the two most important tributaries of the White Nile in terms of discharge. The Bahr al Ghazal's drainage basin

475-554: A flood-prone property to qualify for government-subsidized insurance, a local community must adopt an ordinance that protects the floodway and requires that new residential structures built in Special Flood Hazard Areas be elevated to at least the level of the 100-year flood. Commercial structures can be elevated or floodproofed to or above this level. In some areas without detailed study information, structures may be required to be elevated to at least two feet above

570-445: A floodplain. The quantity of sediments in a floodplain greatly exceeds the river load of sediments. Thus, floodplains are an important storage site for sediments during their transport from where they are generated to their ultimate depositional environment. When the rate at which the river is cutting downwards becomes great enough that overbank flows become infrequent, the river is said to have abandoned its floodplain. Portions of

665-546: Is a problem in freshwater systems. Much of the phosphorus in freshwater systems comes from municipal wastewater treatment plants and agricultural runoff. Stream connectivity controls whether phosphorus cycling is mediated by floodplain sediments or by external processes. Under conditions of stream connectivity, phosphorus is better able to be cycled, and sediments and nutrients are more readily retained. Water in freshwater streams ends up in either short-term storage in plants or algae or long-term in sediments. Wet/dry cycling within

760-413: Is a tourist destination, and a centre of production of natural organic products. The tourism and economic demarcation of the Spree Forest is thus much more difficult than its geographical extension. Due to its popularity and the associated advantage, the borders of the Spree Forest tourism and business area have increasingly extended beyond the original bounds of the Spree Forest. This is particularly true of

855-406: Is advantageous for the rapid colonization of large areas of the floodplain. This allows them to take advantage of shifting floodplain geometry. For example, floodplain trees are fast-growing and tolerant of root disturbance. Opportunists (such as birds) are attracted to the rich food supply provided by the flood pulse. Floodplain ecosystems have distinct biozones. In Europe, as one moves away from

950-465: Is an archaeological site located in alluvial deposits formed by an ancient channel of the Nile in the Affad region of southern Dongola Reach , Sudan. There are two theories about the age of the integrated Nile. One is that the integrated drainage of the Nile is of young age and that the Nile basin was formerly broken into series of separate basins, only the most northerly of which fed a river following

1045-401: Is an area of land adjacent to a river . Floodplains stretch from the banks of a river channel to the base of the enclosing valley, and experience flooding during periods of high discharge . The soils usually consist of clays, silts , sands, and gravels deposited during floods. Because of regular flooding, floodplains frequently have high soil-fertility since nutrients are deposited with

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1140-498: Is any area subject to inundation by a 100-year flood. A problem is that any alteration of the watershed upstream of the point in question can potentially affect the ability of the watershed to handle water, and thus potentially affects the levels of the periodic floods. A large shopping center and parking lot, for example, may raise the levels of 5-year, 100-year, and other floods, but the maps are rarely adjusted and are frequently rendered obsolete by subsequent development. In order for

1235-642: Is approximately 1,218 m /s (43,000 cu ft/s) in October and minimum flow is about 609 m /s (21,500 cu ft/s) in April. This fluctuation is caused by the substantial variation in the flow of the Sobat, which has a minimum flow of about 99 m /s (3,500 cu ft/s) in March and a peak flow of over 680 m /s (24,000 cu ft/s) in October. During the dry season (January to June)

1330-460: Is described as vertical accretion , since the deposits build upwards. In undisturbed river systems, overbank flow is frequent, typically occurring every one to two years, regardless of climate or topography. Sedimentation rates for a three-day flood of the Meuse and Rhine Rivers in 1993 found average sedimentation rates in the floodplain of between 0.57 and 1.0 kg/m . Higher rates were found on

1425-755: Is in Egypt. Below the Aswan Dam , at the northern limit of Lake Nasser, the Nile resumes its historic course. North of Cairo , the Nile splits into two branches (or distributaries) that feed the Mediterranean: the Rosetta Branch to the west and the Damietta to the east, forming the Nile Delta . The annual sediment transport by the Nile in Egypt has been quantified. Below the confluence with

1520-565: Is largely a result of flood control, hydroelectric development (such as reservoirs), and conversion of floodplains to agriculture use. Transportation and waste disposal also have detrimental effects. The result is the fragmentation of these ecosystems, resulting in loss of populations and diversity and endangering the remaining fragments of the ecosystem. Flood control creates a sharper boundary between water and land than in undisturbed floodplains, reducing physical diversity. Floodplain forests protect waterways from erosion and pollution and reduce

1615-402: Is most common in sections of rivers where the river bed is accumulating sediments ( aggrading ). Repeated flooding eventually builds up an alluvial ridge, whose natural levees and abandoned meander loops may stand well above most of the floodplain. The alluvial ridge is topped by a channel belt formed by successive generations of channel migration and meander cutoff. At much longer intervals,

1710-572: Is the largest of any of the Nile's sub-basins, measuring 520,000 square kilometers (200,000 sq mi) in size, but it contributes a relatively small amount of water, about 2 m /s (71 cu ft/s) annually, because tremendous volumes of water are lost in the Sudd wetlands. The Sobat River, which joins the Nile a short distance below Lake No, drains about half as much land, 225,000 km (86,900 sq mi), but contributes 412 cubic meters per second (14,500 cu ft/s) annually to

1805-545: Is traditionally considered to be the headwaters stream. However, the Blue Nile is the source of most of the water of the Nile downstream, containing 80% of the water and silt . The White Nile is longer and rises in the Great Lakes region. It begins at Lake Victoria and flows through Uganda and South Sudan. The Blue Nile begins at Lake Tana in Ethiopia and flows into Sudan from the southeast. The two rivers meet at

1900-660: The Spreewaldkähne . The landscape was shaped during the last Ice Age . The region's most populous towns are Lübbenau/Spreewald ( L.S. Lubnjow/Błota), which is known for the incorporated villages of Lehde (Lědy) and Leipe (Lipje), the villages with canals instead of streets, and Lübben (Spreewald) (Lubin (Błota)). Other notable towns are Vetschau/Spreewald (Wětošow/Błota) with its reconstructed Old Slavic fortified wooden settlement ( gord ) Slawenburg Raddusch ( Radušańske słowjańske groźišćo ), and Burg (Spreewald) (Bórkowy (Błota)). About 50,000 people live in

1995-644: The Democratic Republic of the Congo , Tanzania , Burundi , Rwanda , Uganda , Kenya , Ethiopia , Eritrea , South Sudan , Sudan , and Egypt . In particular, the Nile is the primary water source of Egypt, Sudan and South Sudan. The Nile is an important economic driver supporting agriculture and fishing. The Nile has two major tributaries : the White Nile and the Blue Nile . The White Nile

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2090-651: The Paleogene and Neogene Periods (66 million to 2.588 million years ago) a series of separate closed continental basins each occupied one of the major parts of the Sudanese Rift System: Mellut rift , White Nile rift , Blue Nile rift , Atbara rift and Sag El Naam rift . The Mellut Basin is nearly 12 kilometers (7.5 mi) deep at its central part. This rift is possibly still active, with reported tectonic activity in its northern and southern boundaries. The Sudd swamp which forms

2185-787: The River Nile or Nile River ) is a major north-flowing river in northeastern Africa . It flows into the Mediterranean Sea . The Nile is the longest river in Africa. It has historically been considered the longest river in the world , though this has been contested by research suggesting that the Amazon River is slightly longer. Of the world's major rivers, the Nile is one of the smallest, as measured by annual flow in cubic metres of water. About 6,650 km (4,130 mi) long, its drainage basin covers eleven countries:

2280-557: The Yellow River in China – see list of deadliest floods . The worst of these, and the worst natural disaster (excluding famine and epidemics), was the 1931 China floods , estimated to have killed millions. This had been preceded by the 1887 Yellow River flood , which killed around one million people and is the second-worst natural disaster in history. The extent of floodplain inundation depends partly on flood magnitude, defined by

2375-456: The discharge at any given point along the main stem depends on many factors including weather, diversions, evaporation and evapotranspiration , and groundwater flow. Upstream from Khartoum (to the south), the river is known as the White Nile , a term also used in a limited sense to describe the section between Lake No and Khartoum. At Khartoum, the river is joined by the Blue Nile . The White Nile starts in equatorial East Africa, and

2470-430: The dry season ) an appreciable incoming surface flow for many kilometres upstream, and found a new source, giving the Nile a length of 6,758 km (4,199 mi). The White Nile leaves Lake Victoria at Ripon Falls near Jinja, Uganda , as the "Victoria Nile." It flows north for some 130 kilometers (81 mi) to Lake Kyoga . The last part of the approximately 200 kilometers (120 mi) river section starts from

2565-747: The return period . In the United States, the Federal Emergency Management Agency (FEMA) manages the National Flood Insurance Program (NFIP). The NFIP offers insurance to properties located within a flood-prone area, as defined by the Flood Insurance Rate Map (FIRM), which depicts various flood risks for a community. The FIRM typically focuses on the delineation of the 100-year flood inundation area, also known within

2660-552: The Bahr al Jabal at a small lagoon called Lake No , after which the Nile becomes known as the Bahr al Abyad , or the White Nile, from the whitish clay suspended in its waters. When the Nile floods it leaves a rich silty deposit which fertilizes the soil. The Nile no longer floods in Egypt since the completion of the Aswan Dam in 1970. An anabranch river, the Bahr el Zeraf , flows out of

2755-652: The Blue Nile begins in Ethiopia. Both branches are on the western flanks of the East African Rift . The source of the Blue Nile is Lake Tana in the Gish Abay region in the Ethiopian Highlands . The source of the White Nile, even after centuries of exploration, remains in dispute. The most remote source that is indisputably a source for the White Nile is the Kagera River ; however,

2850-569: The Blue Nile the only major tributary is the Atbarah River , also known as the Red Nile. Roughly halfway to the sea, it originates in Ethiopia north of Lake Tana , and is around 800 kilometers (500 mi) long. The Atbarah flows only while there is rain in Ethiopia and dries very rapidly. During the dry period of January to June, it typically dries up north of Khartoum . The Blue Nile ( Amharic : ዓባይ , ʿĀbay ) springs from Lake Tana in

2945-589: The Congo, but the Nile is not a border river at this point. After leaving Lake Albert, the river continues north through Uganda and is known as the Albert Nile . The White Nile flows into South Sudan just south of Nimule , where it is known as the Bahr al Jabal ("Mountain River" ). Just south of the town is the confluence with the Achwa River . The Bahr al Ghazal , 716 kilometers (445 mi) long, joins

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3040-537: The Delta, and would have been pronounced ni-lo-he in the area around Memphis in the 8th century BCE. Hesiod at his Theogony refers to Nilus (Νεῖλος) as one of the Potamoi (river gods), son of Oceanus and Tethys . Another derivation of Nile might be related to the term Nil ( Sanskrit : नील , romanized :  nila ; Egyptian Arabic : نيلة ), which refers to Indigofera tinctoria , one of

3135-414: The Ethiopian rainy season when rainfall is especially high in the Ethiopian Highlands ; the rest of the year, the great rivers draining Ethiopia into the Nile have a weaker flow. In harsh and arid seasons and droughts, the Blue Nile dries out completely. The flow of the Blue Nile varies considerably over its yearly cycle and is the main contribution to the large natural variation of the Nile flow. During

3230-630: The Ethiopian Highlands, satellite imagery was used to identify dry watercourses in the desert to the west of the Nile. A canyon, now filled by surface drift, represents the Eonile that flowed during 23–5.3 million years before present. The Eonile transported clastic sediments to the Mediterranean; several natural gas fields have been discovered within these sediments. During the late- Miocene Messinian salinity crisis , when

3325-491: The Ethiopian Highlands. The Blue Nile flows about 1,400 kilometres to Khartoum, where the Blue Nile and White Nile join to form the Nile. Ninety percent of the water and ninety-six percent of the transported sediment carried by the Nile come from the Atbarah and Blue Nile, both of which originate in Ethiopia, with fifty-nine percent of the water coming from the Blue Nile. The erosion and transportation of silt only occurs during

3420-874: The Kagera has tributaries that are in contention for the farthest source of the White Nile. Two start in Burundi: the Ruvyironza River (also known as the Luvironza) and the Rurubu River . In addition, in 2010, an exploration party in Rwanda went to a place described as the source of the Rukarara tributary, and by hacking a path up steep jungle-choked mountain slopes in the Nyungwe Forest found (in

3515-482: The Mediterranean Sea was a closed basin and evaporated to the point of being empty or nearly so, the Nile cut its course down to the new base level until it was several hundred metres below world ocean level at Aswan and 2,400 m (7,900 ft) below Cairo. This created a very long and deep canyon which was filled with sediment after the Mediterranean was recreated. At some point the sediments raised

3610-581: The Middle East and Africa, and described being told of the source of the Nile in Abyssinia (Ethiopia). Later in the 15th and 16th centuries, travelers to Ethiopia visited Lake Tana and the source of the Blue Nile in the mountains south of the lake. Supposedly, Paolo Trevisani ( c.  1452 –1483), a Venetian traveller in Ethiopia, wrote a journal of his travels to the origin of the Nile that has since been lost. Although James Bruce claimed to be

3705-560: The NFIP as the Special Flood Hazard Area. Where a detailed study of a waterway has been done, the 100-year floodplain will also include the floodway, the critical portion of the floodplain which includes the stream channel and any adjacent areas that must be kept free of encroachments that might block flood flows or restrict storage of flood waters. Another commonly encountered term is the Special Flood Hazard Area, which

3800-624: The Nile near the southern point of the Great Bend. The Nile has been the lifeline of civilization in Egypt since the Stone Age , with most of the population and all of the cities of Egypt developing along those parts of the Nile valley lying north of Aswan. However, the Nile used to run much more westerly through what is now Wadi Hamim and Wadi al Maqar in Libya and flow into the Gulf of Sidra . As

3895-526: The Nile since ancient times. A tune, Hymn to the Nile , was created and sung by the ancient Egyptian peoples about the flooding of the Nile River and all of the miracles it brought to Ancient Egyptian civilization. Water buffalo were introduced from Asia, and the Assyrians introduced camels in the 7th century BCE. These animals were raised for meat and were domesticated and used for ploughing—or in

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3990-454: The Nile valley north of the Aswan Dam . Nearly all the cultural and historical sites of Ancient Egypt developed and are found along river banks. The Nile is, with the Rhône and Po , one of the three Mediterranean rivers with the largest water discharge . The standard English names "White Nile" and "Blue Nile" refer to the river's source, derived from Arabic names formerly applied to only

4085-523: The Nile's Bahr al Jabal section and rejoins the White Nile. The flow rate of the Bahr al Jabal at Mongalla is almost constant throughout the year and averages 1,048 m /s (37,000 cu ft/s). After Mongalla, the Bahr Al Jabal enters the enormous swamps of the Sudd region. More than half of the Nile's water is lost in this swamp to evaporation and transpiration . The average flow rate of

4180-595: The Nile. When in flood the Sobat carries a large amount of sediment, adding greatly to the White Nile's color. The Yellow Nile is a former tributary that connected the Ouaddaï highlands of eastern Chad to the Nile River Valley c.  8000 to c.  1000 BCE . Its remains are known as the Wadi Howar . The wadi passes through Gharb Darfur near the northern border with Chad and meets up with

4275-532: The Sudanese capital of Khartoum . The northern section of the river flows north almost entirely through the Nubian Desert to Cairo and its large delta , and the river flows into the Mediterranean Sea at Alexandria . Egyptian civilization and Sudanese kingdoms have depended on the river and its annual flooding since ancient times. Most of the population and cities of Egypt lie along those parts of

4370-425: The Sudanese stretches that meet at Khartoum . In the ancient Egyptian language , the Nile is called Ḥꜥpy (Hapy) or Jtrw (Iteru), meaning "river". In Coptic , the word ⲫⲓⲁⲣⲟ , pronounced piaro ( Sahidic ) or phiaro ( Bohairic ), means "the river" (lit. p(h).iar-o "the.canal-great"), and comes from the same ancient name. In Nobiin , the river is called Áman Dawū , meaning "the great water". In Luganda ,

4465-554: The Sudd wetlands of South Sudan, the upper reaches of the White Nile remained largely unknown to the ancient Greeks and Romans. Vitruvius thought that source of the Nile was in Mauritania, on the "other" (south) side of the Atlas Mountains . Various expeditions failed to determine the river's source. Agatharchides records that in the time of Ptolemy II Philadelphus , a military expedition had penetrated far enough along

4560-408: The White Nile at the tails of the swamps is about 510 m /s (18,000 cu ft/s). From here it meets with the Sobat River at Malakal . On an annual basis, the White Nile upstream of Malakal contributes about 15% of the total outflow of the Nile. The average flow of the White Nile at Lake Kawaki Malakal, just below the Sobat River, is 924 m /s (32,600 cu ft/s); the peak flow

4655-512: The White Nile contributes between 70% and 90% of the total discharge from the Nile. Below Renk , the White Nile enters Sudan, it flows north to Khartoum and meets the Blue Nile. The course of the Nile in Sudan is distinctive. It flows over six groups of cataracts , from the sixth at Sabaloka just north of Khartoum northward to Abu Hamad . The tectonic uplift of the Nubian Swell diverts

4750-400: The abandoned floodplain may be preserved as fluvial terraces . Floodplains support diverse and productive ecosystems . They are characterized by considerable variability in space and time, which in turn produces some of the most species-rich of ecosystems. From the ecological perspective, the most distinctive aspect of floodplains is the flood pulse associated with annual floods, and so

4845-511: The advantages provided by the richness of the alluvial soil of the floodplain are severely offset by frequent floods brought on by cyclones and annual monsoon rains. These extreme weather events cause severe economic disruption and loss of human life in the densely-populated region. Floodplain soil composition is unique and varies widely based on microtopography. Floodplain forests have high topographic heterogeneity which creates variation in localized hydrologic conditions. Soil moisture within

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4940-606: The afterlife. The east was thought of as a place of birth and growth, and the west was considered the place of death, as the god Ra , the Sun, underwent birth, death, and resurrection each day as he crossed the sky. Thus, all tombs were west of the Nile, because the Egyptians believed that in order to enter the afterlife, they had to be buried on the side that symbolized death. As the Nile was such an important factor in Egyptian life,

5035-482: The ancient calendar was even based on the three cycles of the Nile. These seasons, each consisting of four months of thirty days each, were called Akhet , Peret , and Shemu . Akhet, which means inundation, was the time of the year when the Nile flooded, leaving several layers of fertile soil behind, aiding in agricultural growth. Peret was the growing season, and Shemu, the last season, was the harvest season when there were no rains. Owing to their failure to penetrate

5130-445: The area is Lübbenau . The Spree Forest gave its name to the following German districts : Alder forests on wetlands and pine forests on sandy dry areas are characteristic of the Spree Forest region. Grasslands and fields can be found as well. About 18,000 species of flora and fauna have been identified. In 1991, the Spree Forest was designated a UNESCO "Biosphärenreservat" (Man and Biosphere Reserve Programme) . The Spree Forest

5225-525: The biosphere reserve (1998). Many of them are descendants of the first settlers in the Spree Forest region, the Slavic tribes of the Sorbs and Wends . They have preserved their traditional language, customs and clothing to this day. Most inhabitants depend on tourism. Many tourists explore the Spree Forest in punts . Agriculture, forestry and fishery are other important sources of income. The principal town of

5320-411: The camels' case, carriage. Water was vital to both people and livestock. The Nile was also a convenient and efficient means of transportation for people and goods. The Nile was also an important part of ancient Egyptian spiritual life. Hapi was the god of the annual floods, and both he and the pharaoh were thought to control the flooding. The Nile was considered to be a causeway from life to death and

5415-479: The central part of the basin may still be subsiding. The White Nile Rift system, although shallower than the Bahr el Arab rift , is about 9 kilometers (5.6 mi) deep. Geophysical exploration of the Blue Nile Rift System estimated the depth of the sediments to be 5–9 kilometers (3.1–5.6 mi). These basins were not interconnected until their subsidence ceased, and the rate of sediment deposition

5510-467: The channel shifts varies greatly, with reported rates ranging from too slow to measure to as much as 2,400 feet (730 m) per year for the Kosi River of India. Overbank flow takes place when the river is flooded with more water than can be accommodated by the river channel. Flow over the banks of the river deposits a thin veneer of sediments that is coarsest and thickest close to the channel. This

5605-463: The course of the Blue Nile to determine that the summer floods were caused by heavy seasonal rainstorms in the Ethiopian Highlands, but no European of antiquity is known to have reached Lake Tana. The Tabula Rogeriana depicted the source as three lakes in 1154. Europeans began to learn about the origins of the Nile in the 14th century when the Pope sent monks as emissaries to Mongolia who passed India,

5700-492: The development of Egyptian civilization. Because the river overflowed its banks annually and deposited new layers of silt, the surrounding land was very fertile. The Ancient Egyptians cultivated and traded wheat, flax , papyrus and other crops around the Nile. Wheat was a crucial crop in the famine-plagued Middle East. This trading system secured Egypt's diplomatic relationships with other countries and contributed to economic stability. Far-reaching trade has been carried on along

5795-402: The dry season the natural discharge of the Blue Nile can be as low as 113 m /s (4,000 cu ft/s), although upstream dams regulate the flow of the river. During the wet season, the peak flow of the Blue Nile often exceeds 5,663 m /s (200,000 cu ft/s) in late August (a difference of a factor of 50). Before the placement of dams on the river the yearly discharge varied by

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5890-410: The etymology is disputed. Homer called the river Αἴγυπτος , Aiguptos , but in subsequent periods, Greek authors referred to its lower course as Neilos ; this term became generalized for the entire river system. Thus, the name may derive from Ancient Egyptian expression n ꜣ r ꜣ w-ḥ ꜣ w(t) (lit. 'the mouths of the front parts'), which referred specifically to the branches of the Nile transversing

5985-508: The first European to have visited the headwaters, modern writers give the credit to the Jesuit Pedro Páez . Páez's account of the source of the Nile is a long and vivid account of Ethiopia. It was published in full only in the early 20th century, although it was featured in works of Páez's contemporaries, including Baltazar Téllez, Athanasius Kircher and Johann Michael Vansleb . Europeans had been resident in Ethiopia since

6080-422: The flood waters. This can encourage farming ; some important agricultural regions, such as the Nile and Mississippi river basins , heavily exploit floodplains. Agricultural and urban regions have developed near or on floodplains to take advantage of the rich soil and freshwater. However, the risk of inundation has led to increasing efforts to control flooding . Most floodplains are formed by deposition on

6175-448: The floodplain ecosystem is defined as the part of the river valley that is regularly flooded and dried. Floods bring in detrital material rich in nutrients and release nutrients from dry soil as it is flooded. The decomposition of terrestrial plants submerged by the floodwaters adds to the nutrient supply. The flooded littoral zone of the river (the zone closest to the river bank) provides an ideal environment for many aquatic species, so

6270-462: The floodplain has a big impact on phosphorus availability because it alters water level, redox state, pH, and physical properties of minerals. Dry soils that were previously inundated have reduced availability of phosphorus and increased affinity for obtaining phosphorus. Human floodplain alterations also impact the phosphorus cycle. Particulate phosphorus and soluble reactive phosphorus (SRP) can contribute to algal blooms and toxicity in waterways when

6365-599: The floodplain. Other smaller-scale mitigation efforts include acquiring and demolishing flood-prone buildings or flood-proofing them. In some floodplains, such as the Inner Niger Delta of Mali , annual flooding events are a natural part of the local ecology and rural economy , allowing for the raising of crops through recessional agriculture . However, in Bangladesh , which occupies the Ganges Delta ,

6460-459: The great lakes. Believing he had found the source of the Nile on seeing this "vast expanse of open water" for the first time, Speke named the lake after Queen Victoria . Burton, recovering from illness and resting further south on the shores of Lake Tanganyika , was outraged that Speke claimed to have proven his discovery to be the true source of the Nile when Burton regarded this as still unsettled. A quarrel ensued which sparked intense debate within

6555-415: The human-caused disconnect between floodplains and rivers exacerbates the phosphorus overload. Floodplain soils tend to be high in eco-pollutants, especially persistent organic pollutant (POP) deposition. Proper understanding of the distribution of soil contaminants is difficult because of high variation in microtopography and soil texture within floodplains. Nile The Nile (also known as

6650-465: The impact of floodwaters. The disturbance by humans of temperate floodplain ecosystems frustrates attempts to understand their natural behavior. Tropical rivers are less impacted by humans and provide models for temperate floodplain ecosystems, which are thought to share many of their ecological attributes. Excluding famines and epidemics , some of the worst natural disasters in history (measured by fatalities) have been river floods, particularly in

6745-448: The inside of river meanders and by overbank flow. Wherever the river meanders, the flowing water erodes the river bank on the outside of the meander. At the same time, sediments are simultaneously deposited in a bar on the inside of the meander. This is described as lateral accretion since the deposition builds the point bar laterally into the river channel. Erosion on the outside of the meander usually closely balances deposition on

6840-417: The inside so that the channel shifts in the direction of the meander without changing significantly in width. The point bar is built up to a level very close to that of the river banks. Significant net erosion of sediments occurs only when the meander cuts into higher ground. The overall effect is that, as the river meanders, it creates a level flood plain composed mostly of point bar deposits. The rate at which

6935-609: The late 15th century, and one of them may have visited the headwaters even earlier without leaving a written trace. The Portuguese João Bermudes published the first description of the Tis Issat Falls in his 1565 memoirs, compared them to the Nile Falls alluded to in Cicero 's De Republica . Jerónimo Lobo describes the source of the Blue Nile, visiting shortly after Pedro Páez. Telles also uses his account. The White Nile

7030-457: The levees (4 kg/m or more) and on low-lying areas (1.6 kg/m ). Sedimentation from the overbank flow is concentrated on natural levees, crevasse splays , and in wetlands and shallow lakes of flood basins. Natural levees are ridges along river banks that form from rapid deposition from the overbank flow. Most of the suspended sand is deposited on the levees, leaving the silt and clay sediments to be deposited as floodplain mud further from

7125-580: The main Nile during the 70,000–80,000 years B.P. wet period. The White Nile system in Bahr El Arab and White Nile Rifts remained a closed lake until the connection of the Victoria Nile to the main system some 12,500 years ago during the African humid period . The Greek historian Herodotus wrote that "Egypt was the gift of the Nile". An unending source of sustenance, it played a crucial role in

7220-617: The makeup towards ash (49%) with maple increasing to 14% and oak decreasing to 25%. Semiarid floodplains have a much lower species diversity. Species are adapted to alternating drought and flood. Extreme drying can destroy the ability of the floodplain ecosystem to shift to a healthy wet phase when flooded. Floodplain forests constituted 1% of the landscape of Europe in the 1800s. Much of this has been cleared by human activity, though floodplain forests have been impacted less than other kinds of forests. This makes them important refugia for biodiversity. Human destruction of floodplain ecosystems

7315-762: The nitrogen-to-phosphorus ratios are altered farther upstream. In areas where the phosphorus load is primarily particulate phosphorus, like the Mississippi River, the most effective ways of removing phosphorus upstream are sedimentation, soil accretion, and burial. In basins where SRP is the primary form of phosphorus, biological uptake in floodplain forests is the best way of removing nutrients. Phosphorus can transform between SRP and particulate phosphorus depending on ambient conditions or processes like decomposition, biological uptake, redoximorphic release, and sedimentation and accretion. In either phosphorus form, floodplain forests are beneficial as phosphorus sinks, and

7410-513: The original sources of indigo dye . Another may be Nymphaea caerulea , known as "The Sacred Blue Lily of the Nile", which was found scattered over Tutankhamun 's corpse when it was excavated in 1922. Another possible etymology derives from the Semitic term Nahal , meaning "river". Old Libyan has the term lilu , meaning water (in modern Berber ilel ⵉⵍⴻⵍ means sea ). With a total length of about 6,650 km (4,130 mi) between

7505-575: The present course of the Nile in Egypt and Sudan. Rushdi Said postulates that Egypt supplied most of the waters of the Nile during the early part of its history. The other theory is that the drainage from Ethiopia via rivers equivalent to the Blue Nile, the Atbara and the Takazze flowed to the Mediterranean via the Egyptian Nile since well back into Tertiary times. Salama suggests that during

7600-462: The region of Lake Victoria and the Mediterranean Sea , the Nile is among the longest rivers on Earth. The drainage basin of the Nile covers 3,254,555 square kilometers (1,256,591 sq mi), about 10% of the area of Africa. Compared to other major rivers, though, the Nile carries little water (5% of that of the Congo River , for example). The Nile basin is complex, and because of this,

7695-739: The regional food industry, as the Spree Forest economic area created for this industry (famed in Germany for the Spreewald gherkin and other pickles ) is much larger than the ecological Spree Forest. This economic area is protected by the Protected Geographical Indication scheme of the EU. Before the legal protection of the space there were several court disputes over the designation Spree Forest on food labels. Floodplain A floodplain or flood plain or bottomlands

7790-685: The river is called Kiira or Kiyira . In Runyoro , it is called Kihiira . In Egyptian Arabic , the Nile is called en-Nīl , while in Standard Arabic it is called an-Nīl . In Biblical Hebrew , it is הַיְאוֹר ‎, Ha-Ye'or or הַשִׁיחוֹר ‎, Ha-Shiḥor . The English name Nile and the Arabic names en-Nîl and an-Nîl both derive from the Latin Nilus and the Ancient Greek Νεῖλος . Beyond that, however,

7885-580: The river may abandon the channel belt and build a new one at another position on the floodplain. This process is called avulsion and occurs at intervals of 10–1000 years. Historical avulsions leading to catastrophic flooding include the 1855 Yellow River flood and the 2008 Kosi River flood . Floodplains can form around rivers of any kind or size. Even relatively straight stretches of river are capable of producing floodplains. Mid-channel bars in braided rivers migrate downstream through processes resembling those in point bars of meandering rivers and can build up

7980-618: The river south-west for over 300 km, following the structure of the Central African Shear Zone embracing the Bayuda Desert . At Al Dabbah it resumes its northward course towards the first cataract at Aswan forming the S-shaped Great Bend of the Nile mentioned by Eratosthenes . In the north of Sudan, the river enters Lake Nasser (known in Sudan as Lake Nubia), the larger part of which

8075-511: The river, the successive plant communities are bank vegetation (usually annuals); sedge and reeds; willow shrubs; willow-poplar forest; oak-ash forest; and broadleaf forest. Human disturbance creates wet meadows that replace much of the original ecosystem. The biozones reflect a soil moisture and oxygen gradient that in turn corresponds to a flooding frequency gradient. The primeval floodplain forests of Europe were dominated by oak (60%) elm (20%) and hornbeam (13%), but human disturbance has shifted

8170-418: The river. Levees are typically built up enough to be relatively well-drained compared with nearby wetlands, and levees in non-arid climates are often heavily vegetated. Crevasses are formed by breakout events from the main river channel. The river bank fails, and floodwaters scour a channel. Sediments from the crevasse spread out as delta -shaped deposits with numerous distributary channels. Crevasse formation

8265-532: The riverbed sufficiently for the river to overflow westward into a depression to create Lake Moeris . Lake Tanganyika drained northwards into the Nile until the Virunga Volcanoes blocked its course in Rwanda. The Nile was much longer at that time, with its furthest headwaters in northern Zambia. The currently existing Nile first flowed during the former parts of the Würm glaciation period. Affad 23

8360-407: The scientific community and interest by other explorers keen to either confirm or refute Speke's discovery. British explorer and missionary David Livingstone pushed too far west and entered the Congo River system instead. It was ultimately Welsh-American explorer Henry Morton Stanley who confirmed Speke's discovery, circumnavigating Lake Victoria and reporting the great outflow at Ripon Falls on

8455-588: The sea level rose at the end of the most recent ice age , the stream which is now the northern Nile captured the ancestral Nile near Asyut . This change in climate also led to the current extents of the Sahara desert, around 3400 BCE. The Giza pyramid complex originally overlooked a branch of the Nile that no longer exists. This branch was highest during the African Humid Period . The existing Nile has five earlier phases: Flowing north from

8550-408: The spawning season for fish often coincides with the onset of flooding. Fish must grow quickly during the flood to survive the subsequent drop in water level. As the floodwaters recede, the littoral experiences blooms of microorganisms, while the banks of the river dry out and terrestrial plants germinate to stabilize the bank. The biota of floodplains has high annual growth and mortality rates, which

8645-459: The surrounding grade. Many State and local governments have, in addition, adopted floodplain construction regulations which are more restrictive than those mandated by the NFIP. The US government also sponsors flood hazard mitigation efforts to reduce flood impacts. California 's Hazard Mitigation Program is one funding source for mitigation projects. A number of whole towns such as English, Indiana , have been completely relocated to remove them from

8740-672: The upper 30 cm of the soil profile also varies widely based on microtopography which affects oxygen availability. Floodplain soil stays aerated for long stretches of time in between flooding events, but during flooding, saturated soil can become oxygen-depleted if it stands stagnant for long enough. More soil oxygen is available at higher elevations farther from the river. Floodplain forests generally experience alternating periods of aerobic and anaerobic soil microbe activity which affects fine root development and desiccation. Floodplains have high buffering capacity for phosphorus to prevent nutrient loss to river outputs. Phosphorus nutrient loading

8835-560: The western shores of the lake and flows at first to the west until just south of Masindi Port , where the river turns north, then makes a great half circle to the east and north to Karuma Falls . For the remaining part, it flows westerly through the Murchison Falls until it reaches the northern shores of Lake Albert where it forms a significant river delta. Lake Albert is on the border of the Democratic Republic of

8930-574: Was enough to fill and connect them. The Egyptian Nile connected to the Sudanese Nile, which captures the Ethiopian and Equatorial headwaters during the current stages of tectonic activity in the Eastern, Central and Sudanese Rift systems. The connection of the different Niles occurred during cyclic wet periods. The Atbarah overflowed its closed basin during the wet periods that occurred about 100,000 to 120,000 years ago. The Blue Nile connected to

9025-597: Was even less understood. The ancients mistakenly believed that the Niger River represented the upper reaches of the White Nile. For example, Pliny the Elder writes that the Nile had its origins "in a mountain of lower Mauretania ", flowed above ground for "many days" distance, then went underground, reappeared as a large lake in the territories of the Masaesyli , then sank again below the desert to flow underground "for

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