Wadis

A widely ramified pattern of wadis –watercourses that are dry most of the year–runs from the border to the Euphrates.

Following infrequent rains in the Ennedi Plateau and Ouaddaï Highlands, water may flow through depressions called enneris and wadis.

Here it is fed only by the wadis of the western desert during the winter rains.

In case of a flood (spate), water is diverted to normally dry river beds (wadis) using a network of dams, gates and channels and spread over large areas.

In many wadis, however, the water table is declining at an alarming rate, particularly in areas of intensive agriculture and near urban centers.

Lucas (1962) p. 413 Ore-bearing rock formations were found in distant, inhospitable wadis in the eastern desert and the Sinai, requiring large, state-controlled expeditions to obtain natural resources found there.

Nicholson (2000) p. 166 High-quality building stones were abundant in Egypt; the ancient Egyptians quarried limestone all along the Nile valley, granite from Aswan, and basalt and sandstone from the wadis of the eastern desert.

Scattered oases, drawing water from springs and wells in the vicinity of the wadis, permit some settled agriculture.

Sharply incised with deep, canyon-like walls, whether flowing or dry the wadis can be formidable obstacles to travel.

The eastern slopes are less steep and are marked by dry river beds ( wadis ) that trace the courses of ancient rivers and continue to lead the rare rainfalls down to the plains.

The wadis are heavily settled because soil in their bottoms is often suitable for agriculture, and the high water table in their vicinity makes them logical locations for digging wells.

Wadis turn for a few hours into raging torrents tearing everything in their path, and their course is regularized.

Western Darfur stands in contrast to northern and eastern Darfur, which are semidesert with little water either from the intermittent streams known as wadis or from wells that normally go dry during the winter months.