Lake Victoria

Lake Victoria is the world’s second largest freshwater lake measured by surface area and the eighth largest lake by volume. It is the largest tropical lake in the world. Lake Victoria, through its single outlet to the north, the Victoria Nile, provides flow to the White Nile. The lake touches the Equator in its northern reaches. The countries of Tanzania, Uganda and Kenya, border the lake and control 49%, 45%, and 6% of the lake surface, respectively.

Lake Victoria receives its water primarily from direct precipitation and 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. Lake Victoria is drained solely by the Nile River near Jinja, Uganda, on the lake’s northern shore. Lake Victoria receives 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.

The Water hyacinth has become a major invasive plant species in Lake Victoria. The release of large amounts of untreated wastewater (sewage), agricultural and industrial runoff directly into Lake Victoria, has greatly increased the nutrient levels of nitrogen and phosphorus in the lake “triggering massive growth of exotic Water hyacinth, which colonised the lake in the late 1990’s.

Phosphorus sedimentation has doubled over the last century and is probably mainly responsible for 7-fold increases in algae communities since the mid 1960’s. Blue-green algae began forming large dense patches on the lake surface in the mid 1980’s, and may be the cause of fish kills in the lake’s open waters.

Other issues include fisheries, nutrient pollution, invasive species, polluted runoff, erosion, toxics, pesticides and watershed habitat alteration.

Physical Characteristics

Description► Lake Victoria has a shoreline of approximately 3,500 km.

Volume► 2,760.00 km3

Surface Area►68,870.00 km2

Depth►Mean depth: 40.0 m; Maximum depth► 80.0 m

Elevation►1,133 m (3,717 ft)

Shoreline length►4,828 km

Residence Time►21.0 years

Age►10,000 – 99,999 years before present

Origin► Tectonic

Type► Fresh; Permanent; Natural

Catchment size► 193,000.00 km2

Catchment/surface area ratio► 3:1

Source: LakeNet  (http://www.worldlakes.org)