The significance of the 1969-75 drought in the Sahel and the subsequent desertification lies not in its severity but in that it followed upon substantial changes in the nature, size, and behaviour of the nomadic pastoral societies. Sinclair and Fryxell(1985) argue that it was the impact of these social changes that began the desertification process. The drought merely exacerbated and expedited a degradation process that was already in train.

   The crucial changes to the pastoral society were precipitated by post-World War II aid which, by its nature and direction, encouraged the expansion of cultivated agriculture in the southern fringes of the Sahel at the expense of the traditional dry season pastures of the pastoralists.

   The second aid intervention was the settling of the nomads. Encouraged by the provision of permanent waters, where previously the natural waters had been ephemeral, and/or enforced by new nationalist governments, nomadism declined dramatically in the early 1960s.

   Cultivation decreased the resources available to the pastoralist and settlement enforced sedentary, year-long grazing of grasslands by a population of humans and cattle that grew rapidly (Brown and Wolf, 1984). This rapid growth in the populations of both pastoralists and cattle, ≈ 3% per year, resulted from the removal of a previously limiting population control, the high mortality rates of the newborn. This control on both human and livestock populations was suppressed by access to medical and veterinary services following settlement. Lamprey (1983) has summarized the intricate social and ecological interaction that develops, and how all increased human activity is transmitted to, and focused on, the land.

   The net result of these initial, catalytic social changes has been the overgrazing of the landscape. The cumulative impact of the unrelenting overgrazing, in concert with the additional stress of drought, was desertification, the degradation of landscapes over extensive areas. Ironically, where bores had been sunk by aid projects to supply permanent water and remove a perceived limitation of ephemeral supplies, large numbers of cattle died of hunger, whereas before they had only rarely died of thirst (Wolf, 1986).

   It is this changing of the nature of the landscape, the removal of more vegetation by grazing animals and humans than the system requires for it to function without change of state, and the initiation and enhancement of soil erosion, that encapsulates desertification. That is, the landscape is transformed to resemble one far less productive, and therefore by association, far more arid, than the climate would otherwise determine (Verstraete,1986).