Bani River at Douna
27-744: The Bani River is the principal tributary of the Niger River in Mali . The river is formed from the confluence of the Baoulé and Bagoé rivers some 160 km (99 mi) east of Bamako and it merges with the Niger near Mopti . Its length is about 1,100 km (680 mi). The Bani River has three main tributaries: the Baoulé that rises near Odienné in Côte d'Ivoire and passes just south of Bougouni ,
54-400: A new river, to be given its own name, perhaps one already known to the people who live upon its banks. Conversely, explorers approaching a new land from the sea encounter its rivers at their mouths, where they name them on their charts, then, following a river upstream, encounter each tributary as a forking of the stream to the right and to the left, which then appear on their charts as such; or
81-400: A river or stream that branches off from and flows away from the main stream. Distributaries are most often found in river deltas . Right tributary , or right-bank tributary , and left tributary , or left-bank tributary , describe the orientation of the tributary relative to the flow of the main stem river. These terms are defined from the perspective of looking downstream, that is, facing
108-594: A year while the northern area around Douna receiving only 700 mm (28 in). For the period 1965-1995 the average annual rainfall for the basin was 1,100 mm (43 in). The rainfall is seasonal with most of the rain falling between May and October. The maximum rainfall occurs in August. The discharge of the Bani River is also highly seasonal, with the maximum flow occurring at the end of September and very little flow between February and June. The river enters
135-449: Is a stream or river that flows into a larger stream ( main stem or "parent" ), river, or a lake . A tributary does not flow directly into a sea or ocean . Tributaries, and the main stem river into which they flow, drain the surrounding drainage basin of its surface water and groundwater , leading the water out into an ocean. The Irtysh is a chief tributary of the Ob river and
162-837: Is a tributary of the Niger River . Flowing northward from the Guinea Highlands of the Fouta Djallon in Guinea , it crosses into southern Mali , where it joins the Niger approximately 40 kilometres (25 mi) upstream of Bamako , the capital of Mali. It forms part of the Ivory Coast-Guinea and Guinea–Mali borders . The Sankarani River watershed, traditionally well suited to crops and rich in iron and gold, covers some 35,500 square kilometres (13,700 sq mi), two-thirds of which are in Guinea, where it
189-411: Is also the longest tributary river in the world with a length of 4,248 km (2,640 mi). The Madeira River is the largest tributary river by volume in the world with an average discharge of 31,200 m /s (1.1 million cu ft/s). A confluence , where two or more bodies of water meet, usually refers to the joining of tributaries. The opposite to a tributary is a distributary ,
216-621: Is joined by three tributaries : the Kourai , Yeremou and Dion Rivers . In Mali, it flows into the Niger River upstream of Bamako near the village of Kourouba . Construction of the Sélingué Dam began in 1980, with the goal of supplying Bamako with electricity; it was inaugurated on 13 December 1982. It and the accompanying hydroelectric plant comprised the largest development project in Malian history up to that time. The plant has
243-600: The Bagoé River that rises near Boundiali in Côte d'Ivoire and the Banifing-Lotio that drains the region around Sikasso . The drainage basin upstream of Douna has an area of 102,000 km (39,000 sq mi), 85% of which lies in southern Mali and 15% in northern Côte d'Ivoire. The annual rainfall varies across the catchment basin with the southern area in Côte d'Ivoire receiving 1,500 mm (59 in)
270-532: The Inland Niger Delta north of San and after the annual rains the river floods (the French word crue is sometimes used) and covers the floodplain. There is a significant inter-annual variation in the rainfall and, as a consequence, in the quantity of water flowing in the river. The drought that started at the beginning of the 1970s led to a very large reduction in the flow and up to the present time
297-720: The Sankarani River near Kourouba and the extension of the area irrigated by the Talo dam. The proposed Djenné dam will retain 0.3 km (0.072 cu mi) of water, significantly more than the Talo dam. It will allow the "controlled flooding" of 14,000 ha of the Pondori floodplain (on the left bank of the river to the south of Djenné) to allow the cultivation of rice and the irrigation of an additional 5000 ha for growing 'floating grass' ( Echinochloa stagnina know locally as bourgou ) for animal feed. The effects of
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#1732772387125324-481: The Selingue Dam's reservoir covered many of them. As of 2008, more than a thousand fishermen caught "between 400 and 1000 kg/day in peak season and 10 to 50 kg/day in low season (March to May)" in the section of the river between the dam and the junction with the Niger. At the height of its power, from the 13th to 16th centuries CE, the capital of the ancient Mali Empire is believed to have been at Niani , on
351-581: The Upper Niger suffered a similar 20% reduction in rainfall but the readings at the Koulikoro gauge station were only reduced to 50% of the earlier values. Because of the accumulated groundwater deficit, even in a year with high rainfall, the discharge of the Bani River is less than in the wet decades of the 1950s and 1960s. In 2006 the Talo Dam was constructed to irrigate parts of the floodplain to
378-419: The average annual discharge of the river (over the period 1952-2002 the average discharge was 13.4 km (3.2 cu mi) . A downstream flow of 10 m (350 cu ft)/s can be maintained during the dry season by opening a sluice gate. From the published information it is unclear how much of the total discharge will be diverted for irrigation and, of the diverted water, how much will drain back into
405-442: The capacity to produce 44.8 million kilowatt-hours of electricity . An irrigation scheme was also implemented, initially to compensate people who had to be moved; it covered 1,200 hectares (3,000 acres), split up among 1943 plot holders, or 60,000 hectares (150,000 acres). The Sankanarni has a discontinuous floodplain over a distance of 170 kilometres (110 mi) in Guinea . The river banks support gallery forests , though
432-506: The dam was highly controversial. The environmental impact assessment commissioned by the African Development Bank was criticised for not fully taking into account the hydrological impact downstream of the dam. The retaining wall is 5 m (16 ft) high and 295 m (968 ft) in length, creating a reservoir with a capacity to retain 0.18 km (0.043 cu mi) of water. This volume represents 1.3% of
459-675: The dams on the flooding of the Inland Niger Delta downstream of Mopti are expected to be modest, as the discharge of the Bani is only one third of that of the Niger: for the period 1952-2002 the average flow at Douna was 424 m (15,000 cu ft)/s compared with 1,280 m (45,000 cu ft)/s for the Niger at Koulikoro . 14°29′N 4°12′W / 14.483°N 4.200°W / 14.483; -4.200 Tributary A tributary , or an affluent ,
486-421: The direction the water current of the main stem is going. In a navigational context, if one were floating on a raft or other vessel in the main stream, this would be the side the tributary enters from as one floats past; alternately, if one were floating down the tributary, the main stream meets it on the opposite bank of the tributary. This information may be used to avoid turbulent water by moving towards
513-417: The first-order tributary being typically 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 . Sankarani River The Sankarani River (French: Fleuve Sankarani )
540-451: The handedness is from the point of view of an observer facing upstream. For instance, Steer Creek has a left tributary which is called Right Fork Steer Creek. These naming conventions are reflective of the circumstances of a particular river's identification and charting: people living along the banks of a river, with a name known to them, may then float down the river in exploration, and each tributary joining it as they pass by appears as
567-469: The opposite bank before approaching the confluence. An early tributary is a tributary that joins the main stem river closer to its source than its mouth, that is, before the river's midpoint ; a late tributary joins the main stem further downstream, closer to its mouth than to its source, that is, after the midpoint. In the United States, where tributaries sometimes have the same name as
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#1732772387125594-666: The river into which they feed, they are called forks . These are typically designated by compass direction. For example, the American River in California receives flow from its North, Middle, and South forks. The Chicago River 's North Branch has the East, West, and Middle Fork; the South Branch has its South Fork, and used to have a West Fork as well (now filled in). Forks are sometimes designated as right or left. Here,
621-484: The river. The downstream effect of the dam will be to delay the arrival of the annual flood and to reduce its intensity. In May 2009 the African Development Bank approved funding for an irrigation dam/weir to be built on the Bani near Soala, a village situated 12 km (7.5 mi) south of Djenné. The dam is one element in a 6-year 66 million USD program that also includes the building of a dam on
648-418: The smaller stream designated the little fork, the larger either retaining its name unmodified, or receives the designation big . 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, third and higher orders, with
675-435: The south of the river near the town of San . Prior to the construction of the dam, these areas were only fully flooded in very wet years, the most recent of which occurred in 1967. The dam is located 43 km (27 mi) west of San, 66 km (41 mi) downstream of Douna and 110 km (68 mi) upstream of Djenné . The dam acts as a weir in that water can flow over the top of the retaining wall. The construction of
702-432: The streams are seen to diverge by the cardinal direction (north, south, east, or west) in which they proceed upstream, sometimes a third stream entering between two others is designated the middle fork; or the streams are distinguished by the relative height of one to the other, as one stream descending over a cataract into another becomes the upper fork, and the one it descends into, the lower ; or by relative volume:
729-420: The volumes are still much lower than those observed in the 1950s and 1960s. The reduction in the flow of the river was much greater than the reduction in the rainfall. The average rainfall for 1981-1989 was 20% less than for 1961-1970 while the discharge of the river was reduced by 75%. The effect of the reduced rainfall was less extreme for other tributaries of the Niger. Over the same period the catchment basin of
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