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69-726: Westpoint Slough is the largest of several sloughs feeding into Redwood Creek in San Mateo County, California , United States. This slough is surrounded by extensive undisturbed marshlands including Greco Island , which forms its northern boundary. The channel of Westpoint Slough contains considerable mudflat areas; moreover, both the marshes and mudflats offer considerable habitat area for local and migratory wildlife, especially birds. Multinational corporation Cargill currently owns 1,436 acres (2.2 sq mi) of salt ponds adjacent to part of Westpoint Slough. Cargill, in conjunction with Arizona-based DMB Associates, has proposed

138-432: A density current that deposits its sediments as turbidites . When the river water is less dense than the basin water, as is typical of river deltas on an ocean coastline, the delta is characterized by hypopycnal flow in which the river water is slow to mix with the denser basin water and spreads out as a surface fan. This allows fine sediments to be carried a considerable distance before settling out of suspension. Beds in

207-411: A sea , or an estuary , into a lake , a reservoir , or (more rarely) into another river that cannot carry away the sediment supplied by the feeding river. Etymologically, the term river delta derives from the triangular shape (Δ) of the uppercase Greek letter delta . In hydrology , the dimensions of a river delta are determined by the balance between the watershed processes that supply sediment and

276-459: A 149 km (93 mi) section of the Rhône was made navigable for small ships up to Seyssel . As of 2017 , the part between Lyon and Sault-Brénaz is closed for navigation. The Saône, which is also canalized, connects the Rhône ports to the cities of Villefranche-sur-Saône , Mâcon and Chalon-sur-Saône . Smaller vessels (up to CEMT class I ) can travel further northwest, north and northeast via

345-485: A common location for civilizations to flourish due to access to flat land for farming, freshwater for sanitation and irrigation , and sea access for trade. Deltas often host extensive industrial and commercial activities, and agricultural land is frequently in conflict. Some of the world's largest regional economies are located on deltas such as the Pearl River Delta , Yangtze River Delta , European Low Countries and

414-537: A delta but enter into the sea in the form of an estuary . Notable examples include the Gulf of Saint Lawrence and the Tagus estuary. In rare cases, the river delta is located inside a large valley and is called an inverted river delta . Sometimes a river divides into multiple branches in an inland area, only to rejoin and continue to the sea. Such an area is called an inland delta , and often occurs on former lake beds. The term

483-533: A fan. The more often the flow changes course, the shape develops closer to an ideal fan because more rapid changes in channel position result in a more uniform deposition of sediment on the delta front. The Mississippi and Ural River deltas, with their bird's feet, are examples of rivers that do not avulse often enough to form a symmetrical fan shape. Alluvial fan deltas, as seen by their name, avulse frequently and more closely approximate an ideal fan shape. Most large river deltas discharge to intra-cratonic basins on

552-399: A few main distributaries. Once a wave-dominated or river-dominated distributary silts up, it is abandoned, and a new channel forms elsewhere. In a tidal delta, new distributaries are formed during times when there is a lot of water around – such as floods or storm surges . These distributaries slowly silt up at a more or less constant rate until they fizzle out. A tidal freshwater delta is

621-535: A flat arid area splits into channels that evaporate as it progresses into the desert. The Okavango Delta in Botswana is one example. See endorheic basin . The generic term mega delta can be used to describe very large Asian river deltas, such as the Yangtze , Pearl , Red , Mekong , Irrawaddy , Ganges-Brahmaputra , and Indus . The formation of a delta is complicated, multiple, and cross-cutting over time, but in

690-556: A highly controversial development of 32,000 people and 12,000 houses on this open space. Pacific Shores Center sits along Westpoint Slough, as does Westpoint Harbor , which is open to the public. The Port of Redwood City , the City of Redwood City , and the Water Emergency Transit Authority are proposing to construct a commuter ferry terminal along the slough. This San Mateo County, California -related article

759-489: A huge toothed "claw"wheel 6.5 metres (21 ft) across to grip the river bed in the shallows to supplement the paddle wheels. In the 20th century, powerful motor barges propelled by diesel engines were introduced, carrying 1,500 tonnes (3,300,000 lb). In 1933, the Compagnie Nationale du Rhône (CNR) was established to improve navigation and generate electricity, also to develop irrigated agriculture and to protect

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828-573: A hypocynal delta dip at a very shallow angle, around 1 degree. Fluvial-dominated deltas are further distinguished by the relative importance of the inertia of rapidly flowing water, the importance of turbulent bed friction beyond the river mouth, and buoyancy . Outflow dominated by inertia tends to form Gilbert-type deltas. Outflow dominated by turbulent friction is prone to channel bifurcation, while buoyancy-dominated outflow produces long distributaries with narrow subaqueous natural levees and few channel bifurcations. The modern Mississippi River delta

897-439: A mature delta with a distributary network. Another way these distributary networks form is from the deposition of mouth bars (mid-channel sand and/or gravel bars at the mouth of a river). When this mid-channel bar is deposited at the mouth of a river, the flow is routed around it. This results in additional deposition on the upstream end of the mouth bar, which splits the river into two distributary channels. A good example of

966-423: A sedimentary deposit formed at the boundary between an upland stream and an estuary, in the region known as the "subestuary". Drowned coastal river valleys that were inundated by rising sea levels during the late Pleistocene and subsequent Holocene tend to have dendritic estuaries with many feeder tributaries. Each tributary mimics this salinity gradient from its brackish junction with the mainstem estuary up to

1035-586: A series of dams and diversion canals, with a navigation lock beside the hydroelectric power plant on each of these canals. The locks were up to 23 metres (75 ft) deep. After building the Génissiat dam on the Upper Rhône (with no lock) in 1948, designed to meet the electricity needs of Paris, twelve hydroelectric plants and locks were built between 1964 and 1980. With a total head of 162 m (531 ft), they produce 13 GWh of electricity annually, or 16% of

1104-447: A simple delta three main types of bedding may be distinguished: the bottomset beds, foreset/frontset beds, and topset beds. This three-part structure may be seen on small scale by crossbedding . Human activities in both deltas and the river basins upstream of deltas can radically alter delta environments. Upstream land use change such as anti-erosion agricultural practices and hydrological engineering such as dam construction in

1173-567: Is 251 cubic metres per second (8,900 cu ft/s). Below the dam, the Rhône receives the waters of the Arve , fed by the Mont Blanc massif, with a visibly higher sediment load and much lower temperature. After a total of 290 kilometres (180 mi) in Switzerland, the Rhône continues west, entering France and the southern Jura Mountains . It turns toward the south, past Lac de Bourget , which

1242-403: Is a stub . You can help Misplaced Pages by expanding it . River delta A river delta is a triangular landform created by the deposition of the sediments that are carried by the waters of a river , where the river merges with a body of slow-moving water or with a body of stagnant water. The creation of a river delta occurs at the river mouth , where the river merges into an ocean ,

1311-542: Is a good example of a fluvial-dominated delta whose outflow is buoyancy-dominated. Channel abandonment has been frequent, with seven distinct channels active over the last 5000 years. Other fluvial-dominated deltas include the Mackenzie delta and the Alta delta. A Gilbert delta (named after Grove Karl Gilbert ) is a type of fluvial-dominated delta formed from coarse sediments, as opposed to gently sloping muddy deltas such as that of

1380-509: Is a major sign that Mars once had large amounts of water. Deltas have been found over a wide geographical range. Below are pictures of a few. Rh%C3%B4ne The Rhône ( / r oʊ n / ROHN , French: [ʁon] ) is a major river in France and Switzerland, rising in the Alps and flowing west and south through Lake Geneva and Southeastern France before discharging into

1449-576: Is called by the Ionians ", including describing the outflow of silt into the sea and the convexly curved seaward side of the triangle. Despite making comparisons to other river systems deltas, Herodotus did not describe them as "deltas". The Greek historian Polybius likened the land between the Rhône and Isère rivers to the Nile Delta, referring to both as islands, but did not apply the word delta. According to

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1518-538: Is so named because the shape of the Nile Delta approximates the triangular uppercase Greek letter delta . The triangular shape of the Nile Delta was known to audiences of classical Athenian drama ; the tragedy Prometheus Bound by Aeschylus refers to it as the "triangular Nilotic land", though not as a "delta". Herodotus 's description of Egypt in his Histories mentions the Delta fourteen times, as "the Delta, as it

1587-846: The Centre -Loire-Briare and Loing Canals to the Seine , via the Canal de la Marne à la Saône (recently often called the " Canal entre Champagne et Bourgogne ") to the Marne , via the Canal des Vosges (formerly called the "Canal de l'Est – Branche Sud") to the Moselle and via the Canal du Rhône au Rhin to the Rhine . The Rhône is infamous for its strong current when the river carries large quantities of water: current speeds up to 10 km/h (6.2 mph) are sometimes reached, particularly in

1656-641: The Greater Tokyo Area . The Ganges–Brahmaputra Delta , which spans most of Bangladesh and West Bengal and empties into the Bay of Bengal , is the world's largest delta. The Selenga River delta in the Russian republic of Buryatia is the largest delta emptying into a body of fresh water, in its case Lake Baikal . Researchers have found a number of examples of deltas that formed in Martian lakes . Finding deltas

1725-812: The Mediterranean Sea ( Gulf of Lion ). At Arles , near its mouth, the river divides into the Great Rhône (French: le Grand Rhône ) and the Little Rhône ( le Petit Rhône ). The resulting delta forms the Camargue region. The river's source is the Rhône Glacier , at the east edge of the Swiss canton of Valais . The glacier is part of the Saint-Gotthard Massif , which gives rise to three other major rivers:

1794-526: The Nile Delta and Colorado River Delta are some of the most extreme examples of the devastation caused to deltas by damming and diversion of water. Historical data documents show that during the Roman Empire and Little Ice Age (times when there was considerable anthropogenic pressure), there was significant sediment accumulation in deltas. The industrial revolution has only amplified the impact of humans on delta growth and retreat. Ancient deltas benefit

1863-996: The Reuss , Rhine and Ticino . The Rhône is, with the Po and the Nile , one of the three Mediterranean rivers with the largest water discharge . The name Rhône continues the Latin Rhodanus name ( Greek Ῥοδανός Rhodanós ) in Greco-Roman geography . The Gaulish name of the river was * Rodonos or * Rotonos (from a PIE root * ret- "to run, roll" frequently found in river names). Names in other languages include German : Rhone [ˈroːnə] ; Walser : Rotten [ˈrotən] ; Italian : Rodano [ˈrɔːdano] ; Arpitan : Rôno [ˈʁono] ; Occitan : Ròse [ˈrɔze, ˈʀɔze] ; and Romansh : Rodan . The Greco-Roman as well as

1932-835: The Swiss Alps , at an altitude of approximately 2,208 metres (7,244 ft). From there it flows southwest through Gletsch and the Goms, the uppermost valley region of the Valais before Brig . In the Brig area, it receives the waters of the Massa from the Aletsch Glacier , the longest glacier of the Alps, and shortly after, it receives the waters of the Vispa , the longest affluent in Valais. After that, it flows onward through

2001-639: The Alps. From Lyon, the Rhône flows south, in its large valley between the Alps and the Massif Central . At Arles , the Rhône divides into two major arms forming the Camargue delta , both branches flowing into the Mediterranean Sea, the delta being termed the Rhône Fan. The larger arm is called the "Grand Rhône", the smaller the "Petit Rhône". The average annual discharge at Beaucaire is 1,700 m /s (60,000 cu ft/s). The main tributaries of

2070-678: The Greek geographer Strabo , the Cynic philosopher Onesicritus of Astypalaea , who accompanied Alexander the Great 's conquests in India , reported that Patalene (the delta of the Indus River ) was "a delta" ( Koinē Greek : καλεῖ δὲ τὴν νῆσον δέλτα , romanized:  kalei de tēn nēson délta , lit.   'he calls the island a delta'). The Roman author Arrian 's Indica states that "the delta of

2139-497: The Mississippi. For example, a mountain river depositing sediment into a freshwater lake would form this kind of delta. It is commonly a result of homopycnal flow. Such deltas are characterized by a tripartite structure of topset, foreset, and bottomset beds. River water entering the lake rapidly deposits its coarser sediments on the submerged face of the delta, forming steeping dipping foreset beds. The finer sediments are deposited on

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2208-764: The Morge and Hermance, the lake is divided by the two countries along its centreline, with the left bank in France. The remainder of the lake is Swiss, including the entire right (north) bank. Here, the tributaries are the Veveyse , the Venoge , the Aubonne , the Morges , among other smaller rivers. Lake Geneva ends in the city of Geneva , where the lake level is controlled by the Le Seujet dam  [ fr ] . The average discharge from Lake Geneva

2277-639: The Rhône are, from source to mouth: The Rhône has been an important highway since the times of the Greeks and Romans . It was the main trade route from the Mediterranean to east-central Gaul . As such, it helped convey Greek cultural influences to the western Hallstatt and the later La Tène cultures. Celtic tribes living near the Rhône included the Seduni , Sequani, Segobriges , Allobroges , Segusiavi , Helvetii , Vocontii and Volcae Arecomici . Navigation

2346-605: The Rhône drains via the Canal de Savières . Continuing generally westward, the Rhône then receives the waters of the Valserine , enters the reservoir created by the Génissiat Dam , and is then joined by the Ain . Reaching Lyon , the most populous city on its course, the Rhône receives its biggest tributary, the Saône , with an average flow of 473 m /s (16,700 cu ft/s), compared to

2415-591: The Rhône's 600 m /s (21,000 cu ft/s) at this point. From this confluence, the Rhône follows a southward course. Along the Rhône Valley, it is joined on the right (western) bank by the rivers Eyrieux , Ardèche , Cèze , and Gardon coming from the Cévennes mountains ; and on the left bank by the rivers Isère , (with an average discharge of 333 m /s (11,800 cu ft/s)), Drôme , Ouvèze , and Durance (188 m /s (6,600 cu ft/s)) from

2484-472: The ability to pile up and accumulate due to the sediment traveling into a steep subduction trench rather than a shallow continental shelf . There are many other lesser factors that could explain why the majority of river deltas form along passive margins rather than active margins. Along active margins, orogenic sequences cause tectonic activity to form over-steepened slopes, brecciated rocks, and volcanic activity resulting in delta formation to exist closer to

2553-485: The adjective derived from the river is rhodanien , as in le sillon rhodanien (literally "the furrow of the Rhône"), which is the name of the long, straight Saône and Rhône river valleys, a deep cleft running due south to the Mediterranean and separating the Alps from the Massif Central . Before railroads and highways were developed, the Rhône was an important inland trade and transportation route, connecting

2622-1256: The basins feeding deltas have reduced river sediment delivery to many deltas in recent decades. This change means that there is less sediment available to maintain delta landforms, and compensate for erosion and sea level rise , causing some deltas to start losing land. Declines in river sediment delivery are projected to continue in the coming decades. The extensive anthropogenic activities in deltas also interfere with geomorphological and ecological delta processes. People living on deltas often construct flood defences which prevent sedimentation from floods on deltas, and therefore means that sediment deposition can not compensate for subsidence and erosion . In addition to interference with delta aggradation , pumping of groundwater , oil , and gas , and constructing infrastructure all accelerate subsidence , increasing relative sea level rise. Anthropogenic activities can also destabilise river channels through sand mining , and cause saltwater intrusion . There are small-scale efforts to correct these issues, improve delta environments and increase environmental sustainability through sedimentation enhancing strategies . While nearly all deltas have been impacted to some degree by humans,

2691-422: The bird's-foot of the Mississippi or Ural river deltas), pushing its mouth into the standing water. As the deltaic lobe advances, the gradient of the river channel becomes lower because the river channel is longer but has the same change in elevation (see slope ). As the gradient of the river channel decreases, the amount of shear stress on the bed decreases, which results in the deposition of sediment within

2760-450: The channel and a rise in the channel bed relative to the floodplain . This destabilizes the river channel. If the river breaches its natural levees (such as during a flood), it spills out into a new course with a shorter route to the ocean, thereby obtaining a steeper, more stable gradient. Typically, when the river switches channels in this manner, some of its flow remains in the abandoned channel. Repeated channel-switching events build up

2829-443: The cities of Arles , Avignon , Valence , Vienne and Lyon to the Mediterranean ports of Fos-sur-Mer , Marseille and Sète . Travelling down the Rhône by barge would take three weeks. By motorized vessel, the trip now takes only three days. The Rhône is classified as a Class V waterway for the 325 km-long (202-mile) section from the mouth of the Saône at Lyon to the sea at Port-Saint-Louis-du-Rhône . Upstream from Lyon,

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2898-509: The country's total hydroelectric production (20% if the Upper Rhône schemes are added). There have been significant benefits for agriculture throughout the Rhône valley. With the Lower Rhône project completed, CNR turned its attention to the Haut-Rhône (Upper Rhône), and built four hydropower dams in the 1980s: Sault-Brénaz, Brégnier-Cordon, Belley-Brens and Chautagne. It also drew up plans for

2967-612: The economy due to their well-sorted sand and gravel . Sand and gravel are often quarried from these old deltas and used in concrete for highways , buildings, sidewalks, and landscaping. More than 1 billion tons of sand and gravel are produced in the United States alone. Not all sand and gravel quarries are former deltas, but for ones that are, much of the sorting is already done by the power of water. Urban areas and human habitation tend to be located in lowlands near water access for transportation and sanitation . This makes deltas

3036-414: The flow enters the standing water, it is no longer confined to its channel and expands in width. This flow expansion results in a decrease in the flow velocity , which diminishes the ability of the flow to transport sediment . As a result, sediment drops out of the flow and is deposited as alluvium , which builds up to form the river delta. Over time, this single channel builds a deltaic lobe (such as

3105-506: The fresh stream feeding the head of tidal propagation. As a result, the tributaries are considered to be "subestuaries". The origin and evolution of a tidal freshwater delta involves processes that are typical of all deltas as well as processes that are unique to the tidal freshwater setting. The combination of processes that create a tidal freshwater delta result in a distinct morphology and unique environmental characteristics. Many tidal freshwater deltas that exist today are directly caused by

3174-466: The geomorphology and ecosystem. Deltas are typically classified according to the main control on deposition, which is a combination of river, wave , and tidal processes, depending on the strength of each. The other two factors that play a major role are landscape position and the grain size distribution of the source sediment entering the delta from the river. Fluvial-dominated deltas are found in areas of low tidal range and low wave energy. Where

3243-614: The historical region of Chablais . It then enters Lake Geneva near Le Bouveret , where the water flows west. On the left (south) bank of Lake Geneva, the river Morge joins at the village of Saint-Gingolph , and also marks the French-Swiss border. Westward, the Dranse (unrelated to the Drance) enters the lake with its preserved delta , and then the Hermance marks another French-Swiss border. Between

3312-406: The lake bottom beyond this steep slope as more gently dipping bottomset beds. Behind the delta front, braided channels deposit the gently dipping beds of the topset on the delta plain. While some authors describe both lacustrine and marine locations of Gilbert deltas, others note that their formation is more characteristic of the freshwater lakes, where it is easier for the river water to mix with

3381-586: The lakewater faster (as opposed to the case of a river falling into the sea or a salt lake, where less dense fresh water brought by the river stays on top longer). Gilbert himself first described this type of delta on Lake Bonneville in 1885. Elsewhere, similar structures occur, for example, at the mouths of several creeks that flow into Okanagan Lake in British Columbia and form prominent peninsulas at Naramata , Summerland , and Peachland . In wave-dominated deltas, wave-driven sediment transport controls

3450-566: The land of the Indians is made by the Indus river no less than is the case with that of Egypt". As a generic term for the landform at the mouth of the river, the word delta is first attested in the English-speaking world in the late 18th century, in the work of Edward Gibbon . River deltas form when a river carrying sediment reaches a body of water, such as a lake, ocean, or a reservoir . When

3519-487: The large glaciers of the massifs of Monte Rosa , Dom , and Grand Combin , but also from the steeper slopes of the Bernese Alps to the north, and the Mont Blanc massif to the west. As a result, the Rhône Valley experiences a drier climate than the rest of Switzerland , being sheltered by the three highest ranges of the Alps, making Valais the driest and largest wine region of the country. At Martigny, where it receives

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3588-524: The onset of or changes in historical land use, especially deforestation , intensive agriculture , and urbanization . These ideas are well illustrated by the many tidal freshwater deltas prograding into Chesapeake Bay along the east coastline of the United States. Research has demonstrated that the accumulating sediments in this estuary derive from post-European settlement deforestation, agriculture, and urban development. Other rivers, particularly those on coasts with significant tidal range , do not form

3657-650: The reconstructed Gaulish name is masculine, as is French le Rhône . This form survives in the Spanish/Portuguese and Italian namesakes, el/o Ródano and il Rodano , respectively. German has adopted the French name but given it the feminine gender, die Rhone . The original German adoption of the Latin name was also masculine, der Rotten ; it survives only in the Upper Valais ( dialectal Rottu ). In French,

3726-480: The result of this process is the Wax Lake Delta . In both of these cases, depositional processes force redistribution of deposition from areas of high deposition to areas of low deposition. This results in the smoothing of the planform (or map-view) shape of the delta as the channels move across its surface and deposit sediment. Because the sediment is laid down in this fashion, the shape of these deltas approximates

3795-573: The river delta, causing the delta to retreat. For deltas that form further upriver in an estuary, there are complex yet quantifiable linkages between winds, tides, river discharge, and delta water levels. Erosion is also an important control in tide-dominated deltas, such as the Ganges Delta , which may be mainly submarine, with prominent sandbars and ridges. This tends to produce a "dendritic" structure. Tidal deltas behave differently from river-dominated and wave-dominated deltas, which tend to have

3864-414: The river water is nearly equal in density to the basin water, the delta is characterized by homopycnal flow , in which the river water rapidly mixes with basin water and abruptly dumps most of its sediment load. Where the river water has a higher density than basin water, typically from a heavy load of sediment, the delta is characterized by hyperpycnal flow in which the river water hugs the basin bottom as

3933-501: The riverside towns and land from flooding. Some progress was made in deepening the navigation channel and constructing scouring walls, but World War II brought such work to a halt. In 1942, following the collapse of Vichy France , Italian military forces occupied southeastern France up to the eastern banks of the Rhône, as part of the Italian Fascist regime's expansionist agenda. In 1948, the French government started construction of

4002-399: The sediment is never piled up in thick sequences due to the sediment traveling and depositing in deep subduction trenches. At the mouth of a river, the change in flow conditions can cause the river to drop any sediment it is carrying. This sediment deposition can generate a variety of landforms, such as deltas, sand bars, spits, and tie channels. Landforms at the river mouth drastically alter

4071-514: The sediment source. When sediment does not travel far from the source, sediments that build up are coarser grained and more loosely consolidated, therefore making delta formation more difficult. Tectonic activity on active margins causes the formation of river deltas to form closer to the sediment source which may affect channel avulsion , delta lobe switching, and auto cyclicity. Active margin river deltas tend to be much smaller and less abundant but may transport similar amounts of sediment. However,

4140-424: The shape of the delta, and much of the sediment emanating from the river mouth is deflected along the coastline. The relationship between waves and river deltas is quite variable and largely influenced by the deepwater wave regimes of the receiving basin. With a high wave energy near shore and a steeper slope offshore, waves will make river deltas smoother. Waves can also be responsible for carrying sediments away from

4209-416: The stretch below the last lock at Vallabrègues and in the relatively narrow first diversion canal south of Lyon. The 12 locks are operated daily from 5:00 a.m. until 9:00 p.m. All operation is centrally controlled from one control centre at Châteauneuf. Commercial barges may navigate during the night hours by authorisation. The Rhône begins as the meltwater of the Rhône Glacier in Valais , in

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4278-597: The trailing edges of passive margins due to the majority of large rivers such as the Mississippi , Nile , Amazon , Ganges , Indus , Yangtze , and Yellow River discharging along passive continental margins. This phenomenon is due mainly to three factors: topography , basin area, and basin elevation. Topography along passive margins tend to be more gradual and widespread over a greater area enabling sediment to pile up and accumulate over time to form large river deltas. Topography along active margins tends to be steeper and less widespread, which results in sediments not having

4347-412: The upper river used barques du Rhône , sailing barges, 30 by 3.5 metres (98 by 11 ft), with a 75-tonne (165,000 lb) capacity. As many as 50 to 80 horses were employed to haul trains of five to seven craft upstream. Goods would be transshipped at Arles into 23-metre (75 ft) sailing barges called allèges d'Arles for the final run down to the Mediterranean. The first experimental steam boat

4416-430: The valley which bears its name and runs initially in a westerly direction about thirty kilometers to Leuk , then southwest about fifty kilometers to Martigny . Down as far as Brig , the Rhône is a torrent; it then becomes a great mountain river running southwest through a glacial valley. Between Brig and Martigny , it collects waters mostly from the valleys of the Pennine Alps to the south, whose rivers originate from

4485-421: The waters of the Drance on its left bank, the Rhône makes a sharp turn towards the north. Heading toward Lake Geneva ( French : Le Léman ), the valley narrows near Saint-Maurice , a feature that has long given the Rhône valley strategic importance for the control of the Alpine passes. The Rhône then marks the boundary between the cantons of Valais (left bank) and Vaud (right bank), separating two parts of

4554-517: The watershed processes that redistribute, sequester, and export the supplied sediment into the receiving basin. River deltas are important in human civilization , as they are major agricultural production centers and population centers. They can provide coastline defence and can impact drinking water supply. They are also ecologically important, with different species' assemblages depending on their landscape position. On geologic timescales , they are also important carbon sinks . A river delta

4623-433: Was built at Lyon by Jouffroy d'Abbans in 1783. Regular services were not started until 1829 and they continued until 1952. Steam passenger vessels 80 to 100 metres (260–330 ft) long made up to 20 km/h (11 kn) and could do the downstream run from Lyon to Arles in a day. Cargo was hauled in bateau-anguilles , boats 157 by 6.35 metres (515.1 by 20.8 ft) with paddle wheels amidships, and bateaux crabes ,

4692-404: Was difficult, as the river suffered from fierce currents, shallows, floods in spring and early summer when the ice was melting, and droughts in late summer. Until the 19th century, passengers travelled in coches d'eau (water coaches) drawn by men or horses, or under sail. Most travelled with a painted cross covered with religious symbols as protection against the hazards of the journey. Trade on

4761-416: Was first coined by Alexander von Humboldt for the middle reaches of the Orinoco River , which he visited in 1800. Other prominent examples include the Inner Niger Delta , Peace–Athabasca Delta , the Sacramento–San Joaquin River Delta , and the Sistan delta of Iran. The Danube has one in the valley on the Slovak–Hungarian border between Bratislava and Iža . In some cases, a river flowing into

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