wadi

A valley or streambed in the desert that is dry except during rainy periods — the Arabic equivalent of the Spanish arroyo. Wadis are the drainage channels of arid landscapes across North Africa, the Arabian Peninsula, and the Middle East, carved by flash floods that may come only a few times a year or a few times a decade. Between floods, wadis serve as travel corridors, gathering places, and sites of settlement — the trees, the wells, and the shade are found in the wadi bed, where the last water sank into the sand.