Recently, international researchers met under the auspices of the Consortium for Research in East African Tropical Ecosystems, in Kisumu, Kenya, to discuss the economic and environmental threats to Lake Victoria.

That Lake Victoria, Africa’s largest fresh water lake is plagued with problems that threaten its survival is no secret.

One researcher, Corrie Hannah, from the Nicholas School of Environment at Duke University in Durham, North Carolina, US, presented a paper on the Aral Sea and made comparisons with Lake Victoria, to draw attention to the fact that the drying up of the lake is not a far fetched idea.

The Aral Sea in Tajikistan, Central Asia, was until the 1800s as big as Lake Victoria, at 68,000 square kilometres. Today, the Aral Sea has completely dried up.

Originally, two rivers, the Syr Darya and Amu Darya, flowed into the Aral Sea, sustaining the sea and communities around it.

But beginning in the 1860s, cotton farming was intensified in Central Asia and particularly along the Syr Darya and Amu Darya, using water diverted from the two rivers. With time more water was diverted from the two rivers to a point when the Syr Darya and Amu Darya were totally cut off from draining into the Aral Sea. And thus started the slow death of the Aral Sea.

So what lessons can East Africa learn from this story and can Lake Victoria go the way of the Aral Sea?

The Aral Sea was the fourth-largest lake in the world, after Lake Victoria, which was the third largest. Lake Victoria is currently 68,800 sq.km and the Aral Sea was originally 68,000 sq. km. Images from Nasa’s Terra satellite taken last year show the Aral Sea has completely dried up for the first time in 600 years.

For comparison, the last time Lake Victoria dried up was 17,300 years ago.

Lake Victoria, though threatened too, has a fairly different story from the Aral Sea, and the climates of their locations are different.

The Aral Sea is in a very arid region of the world. Its primary source of water was from the two main rivers that fed into it. Lake Victoria on the other hand, receives a lot of its water from rainfall over the lake and rivers and streams that flow into it, the major ones being the Kagera in Tanzania; the Nzoia, Yala, Sondu Mirui and Nyando rivers in Kenya.

Lake Victoria is also considered the primary source of the River Nile and drains out at Ripon Falls near Jinja in Uganda. If the inflow of water goes down, the outflow will also be affected, putting at risk the lives of people as far north downstream as Egypt.

The Aral Sea suffered environmental degradation because of the diversion of its inflow waters. Although Lake Victoria suffers no such effects yet, the reduction of water inflow from the highlands and environmental degradation on its riparian lands caused by population pressures pose the same threat.

The general population density around the Lake Victoria basin is increasing every decade, causing an increase in pollution.

Of particular concern is the discharge of raw sewage into the lake and the invasion of the lake by the water hyacinth (eichhornia crassipes), which has increased due to sewage pollution and runoff water coming from agriculture and industrial activity in the lake’s surrounding areas. The introduction of exotic fish species has also had a major impact on the lake’s biodiversity.  

The other major concern is that of climate change. East Africa is generally getting drier, with less rainfall being recorded, meaning less water flowing into the lake; and the high temperatures in the lake basin have increased the evaporation rate.

The ultimate consequences from all these is that a dried up lake will spell social and economic doom for communities and biodiversity.