Lake Turkana, formerly Lake Rudolf, lies in the Rift Valley of East Africa. It is approximately 240 km long and 40 km wide, with an average depth of about 35 m.

These images show the delta of the Omo River, which provides more than 80% of the water to the lake. The lake has no outlet and lies in a very arid area.

The delta increased by about 380 sq km between 1973 and 1989, due to a drop in the water level. Aquatic vegetation took hold on the emerging delta. Prolonged drought and the damming of three rivers for irrigation near the southern reaches of the lake contributed to the lake's decline.

Question

Even without seeing the images, what is one change in the water that you would expect from a reduction in lake volume? (See one answer below.)

References

Johnson, Thomas, C., Halfman, John, D., Rosendahl, Bruce, R., and Lister, Guy, S., 1987, Climatic and tectonic effects on sedimentation in a rift-valley lake: Evidence from high-resolution seismic profiles, Lake Turkana, Kenya: Geological Society of America Bulletin, Geological Society of America, Inc., Boulder, Colorado, vol. 98, no. 4, April, p. 439-447.

Nelson, Harold, D., (ed.), 1984, Kenya: a country study: Federal Areas Studies: The American University, Washington, D. C., 334 p.

Satellite images

LM1182057007303290 (Landsat 1 MSS, 1 February 1973)

LM4169057008901290 (Landsat 4 MSS, 12 January 1989)

LT5169057009503710 (Landsat 5 TM, 6 February 1995)

Special Projects Image

A comparison image of 1 February 1973 and 12 January 1989 is available as Special Projects Image E-1869-810CT from the U.S. Geological Survey (USGS) Center for Earth Resources Observation and Science (EROS) Customer Services.

Map

Defense Mapping Agency, 1988 (compiled 1966, aeronautical and CHUM information revised 1988), Operational Navigation Chart L-5: edition 6, scale 1:1,000,000.

The salinity of the lake increased. Evaporating water leaves its solutes (dissolved salts) behind, and since the lake has no outlet, the salt concentration increases.

A question to think about:

The El Molo, Africa's smallest tribe with just over 200 members, live along the lake's southeastern shore. They fish and hunt Nile crocodiles along the lake shore. What effect do you think increased salinity has had on them?