|- right||Duma River (Tanzania)|
|- elevation||1,680 m (5,512 ft)|
|- location||Speke Gulf, Lake Victoria|
|- elevation||1,133 m (3,717 ft)|
|Length||180 km (112 mi)|
|Basin||10,800 km2 (4,170 sq mi)|
The Simiyu River is a river in Tanzania. It flows into Lake Victoria in the African Great Lakes region. As one of the six main inlets to Lake Victoria, it forms part of the upper headwaters of the Nile.
The Simiyu arises on the western slopes of Mount Loolmalassin and the Ngorongoro Highlands. It flows across the Serengeti into Magu Bay of the Speke Gulf of Lake Victoria. The Simiyu has two main tributaries entering from the right, the Duma River and the Komahola River, and one from the left the Maloho River. There is considerable farming in the lower reaches of the Simiyu Basin, which causes runoff of fertilizers and pesticides. The delta of the Simiyu is a marsh that starts just downstream from the town of Magu. Upstream from Magu just below the Ndagalu Forest Reserve is the village of Samilunga.
There are two rainy seasons, the light one from November into January, and the heavy one from March to May, which result in 700 to 1000 mm of annual rainfall. Less than 10% of the rainfall makes it to the mouth of the river due to a very high evapotranspiration rate.
Average monthly flow of Simiyu measured at the hydrological station in Magu Mjini Estate, about 10 km above the mouth in m³ / s (1999–2004). The Simiyu flows stimulate time-dependent, like most rivers in the region.
- Simiyu River (Approved) at GEOnet Names Server, United States National Geospatial-Intelligence Agency
- Magu Bay (Approved) at GEOnet Names Server, United States National Geospatial-Intelligence Agency
- Duma River (Approved) at GEOnet Names Server, United States National Geospatial-Intelligence Agency
- Komahola (Approved) at GEOnet Names Server, United States National Geospatial-Intelligence Agency
- Survey and Mapping Division, Ministry of Lands, Housing and Urban Development (1982), Topographic Map 1:250,000, Malya, SA 36-11, United Republic of Tanzania
- Rwetabula, J.; De Smedt, F. and Rebhun, M. (2007). "Prediction of runoff and discharge in the Simiyu River (tributary of Lake Victoria, Tanzania) using the WetSpa model" (PDF). Hydrology and Earth System Sciences Discussions 4: 881–908. doi:10.5194/hessd-4-881-2007.
- Ndagalu Central Government Forest Reserve (Approved) at GEOnet Names Server, United States National Geospatial-Intelligence Agency
- Jeal, Tim (2007). Stanley: The Impossible Life of Africa's Greatest Explorer. New Haven, Connecticut: Yale University Press. p. 171. ISBN 978-0-300-12625-9.
- Stanley, H.M., 1899, Through the Dark Continent, London: G. Newnes, ISBN 0486256677