wadi

n. dry river valley, streambed that is dry most of the year (except in the event of heavy rains)

( ) is traditionally a valley. In some cases it can refer to a dry riverbed that contains water only during times of heavy rain. Compare arroyo (creek), canyon, gulch, wash and gully.The term is very widely found in Arabic toponyms. Wadis tend to be associated with centers of human population because sub-surface water is sometimes available in wadis. Crossing wide wadis at certain times of the year can be dangerous, because of unexpected flash floods. Such flash floods cause many deaths each year in Saudi Arabia and many other Middle Eastern countries.
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Noun
1. gully or streambed in northern Africa and the Middle East that remains dry except during rainy season
(hypernym) gully

n. wadi, dry river valley

Synonyms and related words:
abysm, abyss, adolescent stream, aqueduct, arroyo, beck, bed, bottom, bottom glade, bottoms, bourn, box canyon, braided stream, branch, breach, break, brook, brooklet, burn, canal, canyon, cavity, channel, chap, chasm, check, chimney, chink, cleft, cleuch, clough, col, coulee, couloir, crack, cranny, creek, creek bed, crevasse, crevice, crick, culvert, cut, cwm, dale, defile, dell, dike, dingle, ditch, donga, draw, dry bed, excavation, fault, fissure, flaw, flowing stream, flume, fluviation, fracture, fresh, freshet, furrow, gap, gape, gash, gill, glen, gorge, groove, grove, gulch, gulf, gully, gullyhole, headrace, hole, incision, intervale, irrigation ditch, joint, kill, kloof, lazy stream, leak, lunar rill, meandering stream, midchannel, midstream, millstream, moat, moving road, navigable river, notch, nullah, opening, pass, passage, race, racing stream, ravine, rent, rift, rime, river, river bed, riverway, rivulet, run, rundle, runlet, runnel, rupture, scissure, seam, sike, slit, slot, sluice, spill stream, spillbox, spillway, split, strath, stream, stream action, stream bed, streamlet, streamway, subterranean river, swash, swash channel, tailrace, trench, trough, vale, valley, void, water carrier, water channel, water furrow, water gap, water gate, watercourse, waterway, waterworks