Shrinking African lakes seen from space

Posted: 1 November 2005

The dramatic and, in some cases damaging environmental changes sweeping Africa's lakes are brought into sharp focus in a new atlas.

The Atlas of African Lakes, produced by the UN Environment Programme (UNEP), shows spectacular satellite images of the past few decades alongside contemporary ones. It was unveiled today (November 1) at the opening of the 11th World Lake Conference taking place in Nairobi, Kenya.

The rapid shrinking of Lake Songor in Ghana, partly as a result of intensive salt production, and the extraordinary changes in the Zambeziriver system as a result of the building of the Cabora Basa dam site are revealed, alongside more familiar images of the near 90 per cent shrinkage of Lake Chad.

Other impacts, some natural and some human-made and which can only be truly appreciated from space, include the extensive deforestation aroundLake Nakuru in Kenya.

Satellite measurements, detailing the falling water levels of Lake Victoria are also mapped. Africa's largest freshwater lake is now about ametre lower than it was in the early 1990s.

Rising populations

Launching the Atlas, Klaus Toepfer, UNEP's Executive Director, stressed the economic importance of Africa's lakes. "In the United States, for example, the value of freshwaters for their recreational value alone is estimated at $37 billion a year."

"I also hope that the images will ring a warning around the world that, if we are to overcome poverty and meet internationally agreed development goals by 2015, the sustainable management of Africa's lakes must be part ofthe equation. Otherwise we face increasing tensions and instability as rising populations compete for life's most precious of precious resources," he added.

These concerns are highlighted in a separate publication, compiled by UNEP and the University of Oregon in the United States, whichassesses the strength of legal agreements between countries sharing the Continent's major water systems.

This report concludes that, in order to reduce tensions between nations, much more needs to be done to beef up shared agreements and treaties toavoid instability in the future.

Volta Basin

It points to the Volta river basin in West Africa, shared between Benin, Burkina Faso, Cote D'Ivoire, Ghana, Mali and Togo, as being a particular source of concern. Over the next two decades, population levels in the region are set to double to around 40 million causing a dramatic demand for water.

Meanwhile rainfall and river flows in the region have declined steadily in the past 30 years with this partly linked to higher evaporation rates as a result of climate change.

"Current water use patterns in the Volts Basin have already stretched the available resources almost to their limits and it will be increasingly difficult to satisfy additional demands," says the report.

"With the sustainability of the Volta Basin under threat, there is urgent need for basin states to co-operate more closely to jointly manage the basin's water resources," it adds.

The Atlas of African Lakes will be published in book form in 2006.

High resolution images of several of the 'before and after' satellite images can be found here or at www.unep.org