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392 - Lake Chad: Inhabitants adapt to lower water levels
December 2011
Lake Chad used to be one of the biggest lakes in the world, but its volume has been reduced to a tenth of what it was in the 1960s. The way this lake has dried up has become a symbol of climate change in action. It’s true that the lake’s water level has always changed, but this hasn’t diminished the major changes to the lifestyle of the inhabitants of the lake’s shoreline. Yet, as demonstrated by a French-Nigerian team including the IRD( 1), lake dwellers have made the best of these changes to their environment. Formerly fishermen or herdsmen, they have become farmers, often growing for export. The land that was part of the lake has made it possible for them to develop highly productive crops such as corn, rice and cowpea. In the valley of the Komadugu Yobe River in Niger, they have even commenced the intensive farming of peppers, which is highly lucrative although risky.
Rewatering the lake, as proposed by the Ubangi( 5) international project, would cause upheaval once again to the farming system, particularly if the yearly rise and fall in lake water levels were to cease.
388 - Revised Earth history favours the search for African gold
November 2011
Potential treasures lie concealed under the West African savannah in some of the Earth’s poorest countries. Extensive gold fields occur, over hundreds of kilometres, from Senegal to Niger. The rapid rise in precious metal prices over the past five years has prompted hugely intensified mineral exploration. Yet new veins must be found if this African gold rush is to continue.
A new discovery, published in Nature Geoscience , is now shaking up our understanding of the Earth and the prospects for exploration. The research team ( 4), led by an IRD geologist, used innovatory modelling software to take a fresh look at the origins of plate tectonics in the light of the geothermal history of the gold deposits in the West African gold fields. These investigations will lead to better ways of locating the emplacement of veins and their depth. This result is a fundamental one for the science which furthermore offers promising applications for West African countries.
384 - Sub-urban agriculture or how to practise effective recycling
September 2011
Since 2008, one out of two human beings is an urban dweller. With the galloping urbanization comes ever more abundant waste. What can be done with all this refuse? Waste management is a major challenge for the coming decades, particularly in Africa.
Sub-urban agriculture offers openings for effective recycling, but does present certain risks. IRD researchers and their partners( 1) surveyed the different farming actors and practices in the Burkina Faso capital, Ouagadougou, seeking a better understanding of the sector and ways of optimizing urban waste management. They found that nearly three quarters of farmers and nurserymen use this type of organic substrate (household waste, poultry feathers, fish scales, septic tank sludge etc.) to fertilize their soils. However, less than one third of them practise composting. Yet, application of raw urban waste on the soils can create serious health risks. As a solution, local councils will have to concentrate on compost awareness campaigns and work to improve accessibility to such materials.
Sub-urban agriculture is proving to be a great advantage for African cities, combining waste conversion, soil improvement and food security.
376 - River Niger’s equilibrium disturbed by the “sand divers”.
June 2011
The upstream bed of the River Niger is becoming deeper year by year. IRD scientists and their research partners( 1) recently described this phenomenon, the opposite of the received idea that the river is sanding up. This incision process is the result of excessive sand and gravel digging for urban expansion, particularly of Bamako and for the nearby construction of infrastructure, such as dams, and other facilities. Indeed the population of Mali’s capital has expanded more than ten-fold in 50 years. Along the Niger there are more than 60 extraction and storage sites, representing a sector employing 15 000 people, mostly “sand divers” who free-dive –without breathing equipment– to gouge the material by hand up from the river floor. The bed is being eroded by these practices, and lowered by several centimetres annually.
Several consequences emerge from this massive uncontrolled exploitation. These include loss of arable land, destabilization of bridges and other structures, lowering of the water level and associated problems for access to water, and reduced productivity of fisheries. And the prospect of further construction on the Niger in the coming years is prompting fears of an acceleration of this process.
372 - Rainfall forecasting could reduce food insecurity
April 2011
Can weather forecasting help improve crop yields in West Africa? IRD scientists and their research partner( 1), bringing together their experience in studying climate, agronomy and economics, have shown recently that millet producers in Niger could increase their income by up to 30%. They do this despite the fact that they often have no option to use other varieties of that cereal. How? Simply by adjusting their strategies in line with forecasts for coming rainy seasons. Previous research investigations have highlighted the advantage of such predictions, but the true impact of climate forecasts on the agricultural economy remains to be determined.
Improvement of the accuracy of predictions and communicating them to farmers can therefore prove to be a strong boost for agricultural development, even in countries of the Sahel like Niger, where low irregular rainfall lend themselves only to crops giving low profitability. Such advances would make West African farming communities more resistant to food insecurity in the forthcoming years and also reduce the poverty of a many small-scale producers.
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