|
Production
Estimates and Crop Assessment Division
Foreign Agricultural Service |
September 26, 2005
Low Water Levels Observed on
Lake Victoria
The
Foreign Agricultural Service's (FAS) Global Reservoir Monitor indicate very low lake levels in
Lake Victoria, the largest lake in
Africa
and major reservoir for the Nile
River. Water levels have remained
above-average for more than 40-years, but current water levels are below
normal and the
lowest level since September, 1961. The lake typically recharges during the upcoming “short
rains” (October-December) and “long rain” (February-June) seasons, but the amount of recharge
this year will be dependent on upcoming seasonal
rainfall amounts and if Uganda’s power utility does not release too much water for power generation.
In addition, FAS monitors the water levels for
nearly 80 lakes worldwide
with satellite radar altimeter and these measurements were compared to water level gauge measurements taken
on Lake Victoria near
Jinja, Uganda from 2000-2004. The results show that the water levels
measured by satellite radar altimeter and water-level gauges are very similar,
and these near-real time satellite measurements will be very useful to monitor critical water-levels on Lake
Victoria in the future.
Water levels of Lake Victoria
are extremely sensitive to moderate changes in rainfall over the lake and rain
catchment basin, with the lake’s large surface area making it the largest
recharge source. The lake’s only
outlet is at Ripon
Falls, located near Jinja Uganda, which is the natural topographic control
that originally formed the lake. In 1954, Owens Falls Dam (later renamed
Nalubaale) was commissioned downstream of Ripon Falls to generate
hydroelectricity along the Victoria Nile river and became Uganda's
largest power station. Several years later in late 1961 and early 1962 (not an El Nino
year), East Africa and Lake Victoria received above-normal rainfall and the lake
unexpectedly rose 2.5 meters following a long period of near constant levels
from the turn of the century. The
hydrology of Lake Victoria
subsequently received lots of research attention and these hydrologic studies later
linked the rapid rise in water levels due to unusual abundant
rainfall over Lake Victoria and East Africa during 1961-1964. Correspondingly, the operating
rule curve at Owens
Falls
was adjusted to maintain “equilibrium” water level for the past 40-years
at approximately 11.9 meters. However,
recent operating practices have exceeded past sustainable operating water
levels because the Nalubaale power station was recently
expanded by the Owens Falls Extension (later renamed Kiira) power station
located about one-kilometer from the Nalubaale power station. The increased hydropower capacity at Nalubaale
and Kiira power stations allowed more water to be released for power generation
and recently lowered
lake levels to unsustainable levels below 11 meters.
In addition, the local press from Uganda
and Kenya
recently reported about the low lake levels for Lake
Victoria.
The Ugandan press (Daily Monitor, September 13-19, 2005) reported that
Uganda has had power shortages for the past five months due to the drastic
lowering of lake water levels, and thus reducing the hydropower
output along the Victoria Nile River at Kiira and Nalubaale power stations. The
Kenyan press (East African Standard,
August 22, 2005) reported that low water levels have forced ships to dock in deeper waters
located away from the shores, affecting inland water transport, agricultural
markets, and trade
between Uganda, Kenya, and Tanzania.
The press article also
mentioned that local fisheries have been affected from the low lake water
levels.
Lake Victoria
is bordered by Kenya, Uganda, and Tanzania
and is one of the most highly populated areas in the world and the surrounding
basin is intensely cultivated. The
lake serves as a valuable resource to the region providing potable water,
hydroelectric power, inland water transport, and supports many different
industries such as agriculture, trade, tourism, wildlife, and fisheries. It is
estimated that the basin serves as a major source of employment for some 30
million people, of which approximately 3 million people are engaged, directly
or indirectly, in subsistence and commercial fishing and more than 80 percent of the
populations engaged in agricultural production, with the majority being small
scale farmers and livestock owners. The
main crops produced are maize, beans, sorghum, millet, paddy rice, and cash
crops such as sugarcane, tea, coffee, cotton, and meat. In
addition, inland water transport on Lake
Victoria serves as alternative transport routes for movement of passengers and
commodities such as fuel, cotton, and grains, with main ports located at Kisumu,
Kenya; Mwanza and Bukoba, Tanzania; and Entebbe, Port Bell and Jinja, Uganda.
Ironically, many of the local communities living near Lake Victoria's unique and vast natural food resource
are among the
poorest and most food insecure in the region due to high population
densities,
widespread poverty, recurrent droughts, crop failures, high mortality rates
(from tuberculosis, malaria, and HIV/AIDS), and environmental degradation
(contamination, pollution, land/forest degradation, biodiversity degradation,
introduction of exotic species, i.e.) from the lake being the final recipient
of human and industrial wastes and eroded soils.
For example, agricultural production in all lakeshore districts
declined in the early and mid-1990s, making the region a net importer of most
farm produce.
Uganda’s Enormous Hydropower Potential
As a way to reduce poverty and
promote economic growth, the Ugandan government in the 1990’s encouraged
investment in the hydropower sector especially in the rural areas where over
90 percent of the population is found. Five
priority hydropower projects were proposed by the
Uganda
government which include the renovation and
expansion of the Nalubaale dam from 180 MW (10 units of 18 MW) to 380 MW (with Kiira power station
producing 200 MW), Bujagali hydro facility (200 MW), Karuma dam (100–200
MW), and a number of smaller hydropower projects.
The new Kiira power station located about one-kilometer downstream from Nalubaale was
inaugurated in 2000 and was targeted to meet additional power demands from Uganda’s growing economy.
The Kiira station has 3 units of 40 MW (120MW) with another 2 units of
40 MW currently being installed.
Further
downstream is the Bujagali (290 MW) hydroelectric power scheme which is
currently being constructed and will open in 2009 at the earliest. In
addition, Uganda is currently seeking funding to finance the Karuma
(100-200MW) hydro project.
Uganda
has enormous hydroelectric potential along the Nile River, but only a fraction of
Uganda's hydroelectric potential has been developed.
Currently, the country's power demand is
greater than supply with just 3-5 percent of the population having regular access to electricity and many towns
not having any power supply, especially in the
north. The lack of hydropower
development in Uganda can be largely attributed to political instability
during the 1970’s and 1980’s, but Uganda’s economy has been growing since the late
1980's.
By the 1990's, economic growth in many sectors throughout Uganda
was constrained by insufficient power capacity and
unreliability of the country’s largest hydropower station at
Nalubaale.
Preliminary
estimates measured the Nile River's hydroelectric potential at 8000 MW and
Uganda's hydroelectric potential along the Victoria Nile River estimated at
nearly 2000 MW, with the 180 MW capacity at Nalubaale in 1999 comprising less than 10 percent of Uganda's hydroelectric potential. In
comparison, it is estimated that the East
African region currently has an installed capacity of 1800 MW. The Nile Basin
Initiative (NBI) proposes to further develop the hydropower potential along the Nile
basin and promote the economic development for the region with rural
electrification. Special concentration will also be given to hydropower
development of the high-potential Lake
Victoria region through the Nile Equatorial Lakes Investment Program (NELSAP).
The Uganda government is involved with these regional development plans and
they privatized their power utility company in 1999 to place them in better
position for private investment and receive international financing for
additional hydropower development.
Other Related Links
Daily
Monitor, "New Power Crises Threatens", (September 13-19, 2005)
East
African Standard, " Low Water Levels Threaten Marine Life in Lake
Victoria", (August 22, 2005)
Uganda’s hydropower
Nile
Basin Initiative
Nile
Equatorial Lakes Investment Program (NELSAP)
Development
and Management of Hydropower Resources in
Uganda
Nile
Basin Hydropower Potential
Other Related Links from the Foreign Agricultural Service (FAS)
Global
Reservoir Monitor
Historical Water Level Elevations for Lake Victoria
Water-Level Gauge Measurements Compared to Satellite
Radar Altimeter Observations
Nile River Basin
Population Density Surrounding Lake Victoria
White Nile Elevation
Profile and Flow Diagram
Photo
of Lake elevation on October 28, 2004 at Kisumu, Kenya
For
more information, contact Curt Reynolds
with the Production Estimates and Crop Assessment Division, at
Curt.Reynolds@fas.usda.gov or
(202) 690-0134.