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20-649: 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 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

40-434: 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 the opposite bank before approaching the confluence. An early tributary

60-513: A discontinuous floodplain over a distance of 170 kilometres (110 mi) in Guinea . The river banks support gallery forests , though 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

80-447: 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 is also the longest tributary river in

100-414: 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 a new river, to be given its own name, perhaps one already known to

120-410: 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: the smaller stream designated the little fork, the larger either retaining its name unmodified, or receives

140-514: 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 the river into which they feed, they are called forks . These are typically designated by compass direction. For example,

160-409: Is given by That is, the i coordinate of the midpoint ( i = 1, 2, ..., n ) is Given two points of interest, finding the midpoint of the line segment they determine can be accomplished by a compass and straightedge construction . The midpoint of a line segment, embedded in a plane , can be located by first constructing a lens using circular arcs of equal (and large enough) radii centered at

180-648: 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, the handedness is from the point of view of an observer facing upstream. For instance, Steer Creek has

200-508: 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 the banks of the Sankarani. 12°00′15″N 8°18′46″W  /  12.00417°N 8.31278°W  / 12.00417; -8.31278 Tributary A tributary , or an affluent , is a stream or river that flows into

220-416: 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 the first-order tributary being typically the least in size. For example, a second-order tributary would be

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240-449: The endpoints. It bisects the segment. The midpoint of a segment in n -dimensional space whose endpoints are A = ( a 1 , a 2 , … , a n ) {\displaystyle A=(a_{1},a_{2},\dots ,a_{n})} and B = ( b 1 , b 2 , … , b n ) {\displaystyle B=(b_{1},b_{2},\dots ,b_{n})}

260-575: 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 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

280-463: The lengths of segments. However, in the generalization to affine geometry , where segment lengths are not defined, the midpoint can still be defined since it is an affine invariant . The synthetic affine definition of the midpoint M of a segment AB is the projective harmonic conjugate of the point at infinity , P , of the line AB . That is, the point M such that H[ A , B ; P , M ] . When coordinates can be introduced in an affine geometry,

300-403: 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 the direction the water current of the main stem is going. In

320-464: 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 the streams are seen to diverge by the cardinal direction (north, south, east, or west) in which they proceed upstream, sometimes

340-417: 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 . Midpoint In geometry , the midpoint is the middle point of a line segment . It is equidistant from both endpoints, and it is the centroid both of the segment and of

360-425: The two definitions of midpoint will coincide. The midpoint is not naturally defined in projective geometry since there is no distinguished point to play the role of the point at infinity (any point in a projective range may be projectively mapped to any other point in (the same or some other) projective range). However, fixing a point at infinity defines an affine structure on the projective line in question and

380-486: The two endpoints, then connecting the cusps of the lens (the two points where the arcs intersect). The point where the line connecting the cusps intersects the segment is then the midpoint of the segment. It is more challenging to locate the midpoint using only a compass, but it is still possible according to the Mohr-Mascheroni theorem . The abovementioned formulas for the midpoint of a segment implicitly use

400-433: 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 , a river or stream that branches off from and flows away from

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