Ọdọ Mmiri Victoria

thumb|Victoria Nyanza. The black line indicates Stanley's route.
.Ọdọ Mmiri Victoria bụ otu n'ime nnukwu ọdọ mmiri Africa.  N'ebe elu dị ihe dịka 59,947 km2 (23,146 sq mi),[1] [2] Ọdọ Mmiri Victoria bụ ọdọ mmiri kachasị ukwuu n'Africa site na mpaghara, ọdọ mmiri kachasị n'ụwa, [3] na ọdọ mmiri ọhụrụ nke abụọ kachasị n'ụwa site na mpaghara elu.  mgbe Lake Superior na North America.[4]  N'ihe gbasara olu, ọdọ mmiri Victoria bụ ọdọ mmiri kọntinent nke itoolu kachasị n'ụwa, nwere ihe dị ka 2,424 km3 (1.965×109 acre⋅ft) mmiri.[2][5]  Ọdọ Mmiri Victoria nwere ịda mbà n'obi na-emighị emi n'Africa.  Ọdọ mmiri ahụ nwere nkezi omimi nke 40 m (130 ft) yana omimi kachasị nke 80–81 m (262–266 ft).[2][5][6]  Mpaghara ndọta ya kpuchiri 169,858 km2 (65,583 sq mi).[7]  Ọdọ mmiri ahụ nwere oke osimiri nke 7,142 km (4,438 mi) mgbe ejiri digitized na ọkwa 1:25,000,[8] nwere agwaetiti nwere 3.7% nke ogologo a.[9]

Agbanyeghi na enwere otutu aha obodo (Dholuo: Nam Lolwe; Luganda: 'Nnalubaale; Kinyarwanda: Nyanza; na Ukerewe), [1] [2] ọdọ mmiri ahụ gbanwere aha Queen Victoria site n'aka onye nyocha John Hanning Speke, onye Britain mbụ depụtara akwụkwọ.  ya na 1858, mgbe ya na Richard Francis Burton na-eme njem.[3][4]  Ọdọ mmiri ahụ bụ ọtụtụ ụdị azụ̀ ndị na-ebighị ebe ọzọ, karịsịa cichlids.  Azụ ndị na-akpa ike, dị ka osimiri Naịl, emewo ka e kpochapụ ọtụtụ ụdị ndị na-akpachapụ anya.
thumb|Topographical map of Lake Victoria
N'ihe gbasara mbara ala, ọdọ mmiri Victoria dị obere na ihe dịka afọ 400,000.  E mere ya mgbe e ji ebe mkpọda gbadara agbachie osimiri ndị na-asọga n'ebe ọdịda anyanwụ.[1]  N'oge Miocene, ihe bụ ugbu a ebe a na-ejide ọdọ mmiri ahụ dị n'akụkụ ọdịda anyanwụ nke ebe a na-ebuli elu nke na-arụ ọrụ dị ka nkewa kọntinent, nke iyi dị n'akụkụ ọdịda anyanwụ na-asọba na mmiri mmiri Congo na iyi dị n'akụkụ ọwụwa anyanwụ na-asọba na ya.  oke osimiri India.  Ka East African Rift System guzobere, mgbidi ọwụwa anyanwụ nke Albertine Rift (ma ọ bụ Western Rift) bilitere, jiri nwayọọ nwayọọ na-atụgharị mmiri na-asọ asọ n'ebe bụ ugbu a Ọdọ Mmiri Victoria.  Mmeghe nke isi ọwụwa anyanwụ Africa Rift na Albertine Rift gbadara mpaghara dị n'etiti ha ka mgbidi ndị ahụ gbawara agbawa na-ebili, na-emepụta ọdọ mmiri ọdọ mmiri Victoria ugbu a.[2]

Ọdọ mmiri Victoria na-enweta pasent 80 nke mmiri ya site na mmiri ozuzo kpọmkwem.[1]  Nkezi ikuku ikuku na ọdọ ahụ dị n'etiti mita 2.0 na 2.2 (6.6 na 7.2 ft) kwa afọ, ọ fọrọ nke nta ka ọ bụrụ okpukpu abụọ nke mmiri ozuzo nke mpaghara mmiri.[2]  Ọdọ Mmiri Victoria na-enwetakwa mmiri ya site na osimiri, na puku kwuru puku obere iyi.  Osimiri Kagera bụ osimiri kachasị ukwuu na-asọba n'ime ọdọ a, ọnụ ya dị n'akụkụ ọdịda anyanwụ nke ọdọ mmiri ahụ.  Ọdọ mmiri Victoria na-agbapụta naanị n'akụkụ Osimiri Naịl dị nso na Jinja, Uganda, n'akụkụ oke osimiri ahụ.[3]  Na mpaghara Kenya, osimiri ndị kacha emetụta bụ Sio, Nzoia, Yala, Nyando, Sondu Miriu, Mogusi, na Migori.

Naanị ihe na-esi n'Ọdọ Mmiri Victoria pụta bụ Osimiri Naịl, nke na-esi n'ọdọ mmiri dị nso na Jinja, Uganda pụta.  N'ihe gbasara mmiri a na-enye onyinye, nke a na-eme Ọdọ Mmiri Victoria ka ọ bụrụ isi iyi nke alaka kacha ogologo nke Naịl.  Otú ọ dị, a na-ewerekarị isi iyi nke osimiri Naịl, ya mere a na-ewerekarị na ọ bụ otu n'ime osimiri ndị na-asọ asọ nke osimiri Kagera (nke bụ kpọmkwem tributary na-anọgide na-adịghị edozi), nke sitere na Rwanda ma ọ bụ  Burundi.  A na-akpọkarị akụkụ kacha elu nke Naịl dị ka Victoria Nile ruo mgbe ọ ruru Ọdọ Albert.  Ọ bụ ezie na ọ bụ akụkụ nke otu usoro osimiri a maara dị ka White Nile na a na-akpọkwa ya mgbe ụfọdụ, n'ikwu okwu nke ọma aha a anaghị emetụta ruo mgbe osimiri ahụ gafechara ókè Uganda banye South Sudan n'ebe ugwu.

The lake is considered a shallow lake considering its large geographic area with a maximum depth of approximately 80 metres (260 ft) and an average depth of 40 metres (130 ft). A 2016 project digitized ten-thousand points and created the first true bathymetric map of the lake. The deepest part of the lake is offset to the east of the lake near Kenya and the lake is generally shallower in the west along the Ugandan shoreline and the south along the Tanzanian shoreline.

Most of these lakes are relatively shallow (like Victoria) and part of the present-day upper Nile basin. The exception is Lake Kivu, which is part of the present-day Congo River basin, but is believed to have been connected to Lakes Edward and Victoria by rivers until the uplifting of parts of the East African Rift. This deep lake may have functioned as an "evolutionary reservoir" for this haplochromine group in periods where other shallower lakes in the region dried out, as happened to Lake Victoria about 15,000 years ago. In recent history only Lake Kyoga was easily accessible to Victoria cichlids, as further downstream movement by the Victoria Nile (to Lake Albert) is prevented by a series of waterfalls, notably Murchison. In contrast, the Owen Falls (now flooded by a dam) between Victoria and Kyoga were essentially a series of rapids that did not effectively block fish movements between the two lakes.

The Victoria haplochromines are distinctly sexually dimorphic (males relatively brightly colored; females dull), and their ecology is extremely diverse, falling into at least 16 groups, including detritivores, zooplanktivores, insectivores, prawn-eaters, molluscivores and piscivores. As a result of predation by the introduced Nile perch, eutrophication and other changes to the ecosystem, it is estimated that at least 200 species (about 40 percent) of Lake Victoria haplochromines have become extinct, including more than 100 undescribed species. Initially it was feared that this number was even higher, by some estimates 65 percent of the total species, but several species that were feared extinct have been rediscovered after the Nile perch started to decline in the 1990s. Several of the remaining species are seriously threatened and additional extinctions are possible. Some species have survived in nearby small satellite lakes, have survived in refugias among rocks or papyrus sedges (protecting them from the Nile perch), or have adapted to the human-induced changes in the lake itself. Such adaptions include a larger gill area (adaption for oxygen-poor water), changes in the feeding apparatus, changes to the eyes (giving them a better sight in turbid water) and smaller head/larger caudal peduncle (allowing faster swimming). The piscivorous (affected by both predation and competition from Nile perch), molluscivorous and insectivorous haplochromines were particularly hard hit with many extinctions. Others have become extinct in their pure form, but survive as hybrids between close relatives (especially among the detritivores). The zooplanktivores have been least affected and in the late 1990s had reached densities similar to, or above, the densities before the drastic declines, although consisting of fewer species and often switching their diet towards macroinvertebrates. Some of the threatened Lake Victoria cichlid species have captive "insurance" populations in zoos, public aquaria and among private aquarists, and a few species are extinct in the wild (only survive in captivity).