What is a wadi / oued (riverbed) in Morocco?

A wadi — spelled oued on almost every Moroccan map and road sign, from the French transliteration of the Arabic — is a watercourse that is dry for most of the year and runs only after rain or when snow melts off the Atlas. In a country this arid, that describes nearly every river. You will cross dozens of bridges over wide, stony, empty channels and wonder where the river is; the answer is that it is a wadi, waiting for its few days of water.

The names are everywhere once you know the word. Oued Drâa is Morocco's longest river, threading the great palm valley south of Ouarzazate; Oued Ziz carves the gorge and oasis you follow down toward Merzouga; Oued Todra and Oued Dadès cut the famous gorges of the same names. Whenever you see 'Oued' on a sign, it is naming the river or its valley — and that valley is usually where you will find the green, the palms, and the villages, because life clusters along the water.

What surprises people is how dangerous a dry wadi can become. The bed is empty and dusty for months, then a thunderstorm in the mountains — sometimes one you cannot even see — sends a flash flood roaring down it within minutes. This is why local drivers never camp in a wadi bed and treat river crossings with respect even under a clear sky. I have watched a bone-dry channel turn into a brown torrent in the time it takes to drink a tea, so when guides say 'do not linger in the oued,' they mean it.

For travellers, the wadi is the thread that ties the desert south together. Follow the oueds and you follow the oases, the kasbahs, and the palm groves — the Drâa, the Ziz, the Todra all trace this exact logic. Walking the floor of a gorge like Todra, you are literally standing in a wadi between thousand-foot walls the water cut. Understanding the word turns a hundred map labels and road signs from gibberish into a clear story about where the water goes and why the towns sit where they do.