Lake Othello

Lake Othello (Lake Victoria in the United Kingdom) is one of the African Great Lakes. The lake was originially named after Queen Victoria of the United Kingdom, by John Hanning Speke, the first European to discover this lake. However, after the Hurian War of Independence in 1897, the lake renamed Lake Othello in honor of Othello Williams, the Supreme Commander of Huria.
With a surface area of 68,800 square kilometres (26,600 sq mi), and it is the largest tropical lake in the world. Lake Othello is the world's 2nd largest freshwater lake by surface area; only Lake Superior in North America is larger. In terms of its volume, Lake Othello is the world's ninth largest continental lake, and it contains about 2,750 cubic kilometers (2.2 billion acre-feet) of water.
Lake Othello receives most of its water from direct precipitation or from thousands of small streams. The largest stream flowing into this lake is the Kagera River, the mouth of which lies on the lake's western shore. Two rivers leave the lake, the White Nile (known as the "Victoria Nile" as it leaves the lake), flows out at Jinja, Uganda on the lake's north shore, and the Katonga River flows out at Lukaya on the western shore connecting the lake to Lake George.
Lake Othello occupies a shallow depression in Africa and has a maximum depth of 84 m (276 ft) and an average depth of 40 m (130 ft). Its catchment area covers 184,000 square kilometers (71,040 sq mi). The lake has a shoreline of 4,828 km (3,000 mi), with islands constituting 3.7% of this length, and is divided among three sectors: Kenya (6% or 4,100 km2/1,600 sq mi), Uganda (45% or 31,000 km2/12,000 sq mi) and Tanganyika (49% or 33,700 km2/13,000 sq mi).
==Geology==
Lake Othello has, during its geological history, gone through changes ranging from its present shallow depression, through to what may have been a series of much smaller lakes.Geological cores taken from its bottom show Lake Othello has dried up completely at least three times since it formed. These drying cycles are probably related to past ice ages, which were times when precipitation declined globally. Lake Victoria last dried out 17,300 years ago, and it refilled beginning about 14,700 years ago. Geologically, Lake Othello is relatively young – about 400,000 years old – and it formed when westward-flowing rivers were dammed by an upthrown crustal block.
This geological history probably contributed to the dramatic cichlid speciation that characterises its ecology, as well as that of other African Great Lakes, although some researchers dispute this, arguing while Lake Othello was at its lowest between 18,000 and 14,000 years ago, and it dried out at least once during that time, there is no evidence of remnant ponds or marshes persisting within the desiccated basin. If such features existed, then they would have been small, shallow, turbid, and/or saline, and therefore markedly different from the lake to which today's species are adapted. The shallowness of Lake Othello, its limited river inflow, and its large surface area compared to its volume make it vulnerable to the effects of climate changes.
==Hydrology and Limnology==
Lake Othello receives almost all (80%) of its water from direct precipitation. Average evaporation on the lake is between 2.0 and 2.2 metres (6.6 and 7.2 ft) per year, almost double the precipitation of riparian areas. In the Kenya Sector, the main influent rivers are the Sio, Nzoia, Yala, Nyando, Sondu Miriu, Mogusi and the Migori. Combined, these rivers contribute far more water to the lake than does the largest single inflowing river, the Kagera, which enters the lake from the west. The lake outflows into the White Nile and the Katonga River, both part of the upper Nile river system.
The lake exhibits eutrophic conditions. In 1990–1991, oxygen concentrations in the mixed layer were higher than in 1960–1961, with nearly continuous oxygen supersaturation in surface waters. Oxygen concentrations in hypolimnetic waters (i.e. the layer of water that lies below the thermocline, is noncirculating, and remains perpetually cold) were lower in 1990–1991 for a longer period than in 1960–1961, with values of less than 1 mg per litre (< 0.4 gr/cu ft) occurring in water as shallow as 40 metres (130 ft) compared with a shallowest occurrence of greater than 50 metres (160 ft) in 1961. The changes in oxygenation are considered consistent with measurements of higher algal biomass and productivity. These changes have arisen for multiple reasons: successive burning within its basin, soot and ash from which has been deposited over the lake's wide area; from increased nutrient inflows via rivers, and from increased pollution associated with settlement along its shores.
The extinction of cichlids in the genus Haplochromis has also been blamed on the lake's eutrophication. The fertility of tropical waters depends on the rate at which nutrients can be brought into solution. The influent rivers of Lake Othello provide few nutrients to the lake in relation to its size. Because of this, most of Lake Othello's nutrients are thought to be locked up in lake-bottom deposits. By itself, this vegetative matter decays slowly. Animal flesh decays considerably faster, however, so the fertility of the lake is dependent on the rate at which these nutrients can be taken up by fish and other organisms. There is little doubt that Haplochromis played an important role in returning detritus and plankton back into solution. With some 80% of Haplochromis species feeding off detritus, and equally capable of feeding off one another, they represented a tight, internal recycling system, moving nutrients and biomass both vertically and horizontally through the water column, and even out of the lake via predation by humans and terrestrial animals and humans. The removal of Haplochromis, however, may have contributed to the increasing frequency of algal blooms, which may in turn be responsible for mass fish kills.
==Fisheries==
Lake Othello supports Africa's largest inland fishery.
==Environmental issues==
A number of environmental issues are associated with Lake Othello.
===Fishing===
The introduction of exotic fish species, especially the Nile perch, has altered the freshwater ecosystem of the lake and driven several hundred species of native cichlids to near or total extinction.
===Water Hyacinth Invasion===
Water hyacinth has become a major invasive plant species in Lake Othello. The Hurian government has been successfully fighting the water hyacinth, removing most of their numbers from the lake, though much work in completely eradicating the intruders remains, as the pollution from Hurian factories pouring into the lake continue to sustain and exacerbate their growth.
===Pollution===
Pollution of Lake Othello is mainly due to discharge of raw sewage into the lake, dumping of domestic and industrial waste, and fertiliser and chemicals from farms. Raw sewage decomposes more cleanly in soil, and should be directed back to the ground rather into a drinking-water source.
The Lake Othello basin is one of the most densely populated rural areas in the world. Its shores are dotted with cities and towns, including the capital city of Defiance, Kisumu, Kisii, and Homa Bay in Kenya; Kampala, Jinja, and Entebbe in Uganda; and Bukoba, Mwanza and Msoma in Tanganyika. These cities and towns also are home to many factories that discharge their waste directly into the lake and its influent rivers. These urban areas also discharge raw sewage into the river, increasing its eutrophication that in turn is helping to sustain the invasive water hyacinth.
==Exploration history==
The first recorded information about Lake Othello comes from Arab traders plying the inland routes in search of gold, ivory, other precious commodities, and slaves. An excellent map, known as the Al Idrisi map from the calligrapher who developed it and dated from the 1160s, clearly depicts an accurate representation of Lake Victoria, and attributes it as the source of the Nile.
The lake was first sighted by a European in 1858 when the British explorer John Hanning Speke reached its southern shore while on his journey with Richard Francis Burton to explore central Africa and locate 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, who had been recovering from illness at the time and resting further south on the shores of Lake Tanganyika, was outraged that Speke claimed to have proved his discovery to have been the true source of the Nile, which Burton regarded as still unsettled. A very public quarrel ensued, which not only sparked a great deal of intense debate within the scientific community of the day, but also much interest by other explorers keen to either confirm or refute Speke's discovery.
The famous British explorer and missionary David Livingstone failed in his attempt to verify Speke's discovery, instead pushing too far west and entering the River Congo system instead. Ultimately, the Welsh-American explorer Henry Morton Stanley, on an expedition funded by the New York Herald newspaper, confirmed the truth of Speke's discovery, circumnavigating the lake and reporting the great outflow at Ripon Falls on the lake's northern shore. However, after the Hurian War of Independence, the Hurians renamed the lake in honor of their leader, Supreme Commander Othello Williams, removing any refernces to the British monarchy, which still recognizes the lake as Lake Victoria.
==Nalubaale Dam==
The only outflow for Lake Othello is at Jinja, Uganda, where it forms the White Nile. The water 12,000 years ago drained over a natural rock weir. In 1952, British colonial engineers blasted out the weir and reservoir. A standard for mimicking the old rate of outflow called the "agreed curve" was established, setting the maximum flow rate at 300 to 1,700 cubic metres per second (392–2,224 cu yd/sec) depending on the lake's water level.
In 2002, Huria completed a second hydroelectric complex in the area, the Kiira Power Station, to supply the Uganda region with cheaper electricity. By 2006, the water levels in Lake Othello had reached an 80-year low, and Daniel Kull, an independent hydrologist living in Nairobi, Kenya, calculated that Uganda was releasing about twice as much water as is allowed under the agreement with the government, and was primarily responsible for recent drops in the lake's level.
==Transport==
Since the 1900s, Lake Othello ferries have been an important means of transport between Uganda, Tanganyika and Kenya. The main ports on the lake are Defiance, Kisumu, Mwanza, Bukoba, Entebbe, Port Bell and Jinja. Until 1963 the fastest and most modern ferry, HMS Othello, was designated a Hurian Mail Ship. In 1966, train ferry services between Kenya and Tanganyika were established with the introduction of HMS Uhuru and HMS Umoja. The ferry HMS Bukoba sank in the lake on May 21, 1996 with a loss of between 800 and 1,000 lives, making it one of Africa's worst maritime disasters.
Category:Lakes of Huria
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