Living Land

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with drought and from their wear with hydraulic transmis-

sion and wind. The intensity of the weathering of rocks and

strong pedogenesis is dependent on weather conditions

(temperature, humidity). Indeed, under hot and humid

conditions, chemical weathering promotes dissolution of

the silica igneous rocks or carbonate limestone elements.

The silting processes are more important and more visible

especially in a hot and dry climate.

These processes have led to three major erosion systems in

the Niger River basin:

• the Guinean system consisting of a feed head, high erosive

power and a spreading and settling zone (Delta basin of

Mali), connected by a transport zone (between Bamako and

Segou), representing 13 per cent of the basin area

• the Sahelo-Saharan system corresponding to the Niger

loop and having a reduced internal power supply

network, unsustainable under dependence of the outlet

of the Delta basin of Mali, representing 58 per cent of the

basin area

• the Nigerian system composed of two well-watered feed

heads with high erosive power (Jos Plateau and Plateau

Yoruba for Niger River, Jos Plateau and Adamawa for

Benue river) and a wide application and sedimentation

area (confluence of oceanic region and delta),

representing 29 per cent of the basin area.

With an annual average growth rate of nearly 3 per cent the

population of the Niger basin, estimated at 113 million in

2005, will reach 160 million in 2020, including 90 million

urban and 70 million rural. The average population density

is 55 inhabitants per km² and rural population density is 37

inhabitants per km². The areas with higher population densi-

ties (30-50 inhabitants per km

) register intense agricultural

activities, often centred on the double production of food

crops and cash crops, including cotton. In the Niger basin it

was found that the high population densities and poor agri-

cultural practices accelerate the silting process.

The main anthropogenic factors of land degradation in the

basin include: rapid population growth (3 per cent per year),

increasing urban consumption of natural resources (40 per

cent of the population live in cities), extensive agriculture

(about 50 per cent of the active area of the Niger basin is

cultured), overgrazing (UBT 31.3 million with an annual

growth rate of 2.4 per cent), overexploitation of wood energy

and the expansion of mining activities.

Approach and intervention techniques

To cope with the accelerated land degradation process of in

the Niger basin, the Niger Basin Authority (NBA) member

countries have adopted different strategies and policies for

sustainable management of natural resources. This political

will has led to the commitment of the NBA in a shared-vision

process with a main component, the development of the

Sustainable Development Action Program (SDAP) including

an investment plan. Three core areas of actions were defined

in the SDAP: the preservation of ecosystems in the basin,

development of socioeconomic infrastructure, and capacity-

building and stakeholder participation.

The African Development Bank and the West African

Economic and Monetary Union (UEMOA) funded a project

(2006-2014) called the ‘Fighting siltation programme in the

Niger River Basin’ (PLCE/BN). The major aim is to effectively

Image: AfDB

Glaze treatment methods include benches to control erosion, like these

ones at Yettoré Allah, Niger

Image: AfDB

Dune fixation in the Gao region, Mali

iving

and