Editing Geography of Mauritania (section)

==Expansion of the desert==
[[Image:Passe de djouk.jpg|thumb|right|240px|The Passe de Djouk, near [[Guerou]]; an increasingly arid area]]
The climate has altered drastically since the onset of the prolonged drought in the 1960s, part of a recurrent pattern of wet and dry cycles common to Sahelian Africa. Experts agree, however, that overgrazing, deforestation, denuding of ground cover around wells, poor farming methods, and overpopulation have aggravated the drought. In Mauritania the isohyet indicating annual rainfall of 150 millimetres—considered the minimum for pastoralism—has shifted southward about 100 kilometres to a point well south of Nouakchott. During the 1980s, the desert was advancing southward at an estimated rate of six kilometres a year. Each major climatic zone had shifted southward, and in some cases near-desert conditions had reached the banks of the Senegal River.

By the late 1980s, desertification had fundamentally altered agro-pastoral and human settlement patterns. Loss of ground cover in the Sahelian Zone had driven animals and people southward in search of food and water and had given rise to new fields of sand dunes. The advancing dunes threatened to engulf wells, villages, and roads; they had even invaded Nouakchott on their march to the sea. The government secured international help to stabilize the dune field around Nouakchott and planted 250,000 palm trees to create a barrier against the encroaching desert. To further combat desiccation, the government constructed dams on the Senegal River and its tributaries to increase the amount of cultivable land.