The hydrographic network is represented mostly desert intermittent beds of temporary streams, where the water is only in the rainy season, and then only a few days. Major rivers originate far from the desert and crossing them, nourish life-giving water only a narrow strip of land along a river bed.
There is a river in the world that exists in dry areas only during the heavy rains of 2-3 h for 3-4 years. In a short time they dump a lot of water and form a short and deeply embedded in the terrain of the valley (wadi). Most of these rivers are found in the Red Sea and the Arabian Peninsula. They cover a dense network of the coastal zone of the Red Sea, reaching almost to the Nile. During the rainy season in this area is very dangerous to be in, as water flows, carried by the wadi, sweep away everything in its path.
In Asian deserts dry beds of temporary streams – saury – during rainstorms also often represent a great danger.
And many of the Central Asian rivers Zarevshan, Soh, Isfara, Chu, Moore Gab – by way of the movement gradually spends its entire stock of water and therefore will not fall.
Lake in the deserts often contain salty or bitter-salty water unsuitable for drinking.
The main sources of drinking water in the desert are groundwater and condensate water, which are formed by the penetration of moisture into the interior of the sand from the rare rains and water that condenses from the atmosphere during the cold snap in the night period.
In most cases, the only source of water in the desert are the groundwater, and to obtain fresh water wells in places digging of underground and ground water.
Horizon of fresh water in the desert is different at different depths. In the Central Asian deserts, it is about 5 m, and in the Sahara and the deserts of the Arabian Peninsula – up to 30 m
Often use water-filled pits. In different places they are called differently. For example, in Central Asia, this nirle. The depth of these wells may reach several tens of meters. This reduces the possibility of penetration of sunlight and thus evaporation. Often over nirle construct domes of mud brick. Such structures are called SARDOBA.
Interested in the water supply, which is a gallery stretching underground for long distances, mostly from the foothills, and repeat the slope areas. Facing brick tunnels eliminates filtration and evaporation does not occur. Such systems transport water found in the deserts of Central Asia, Arabia and North Africa. The only difference is in the name: Central Asia is kiryaz, in the Sahara – foggar.
Most caravan routes, trails and highways in the desert pass through water sources, but the distance between wells and oases can exceed 100 km.