|HYDROGENESIS AND HIDDEN PRECAPTATION
Definition characters description and diffusion
Real artificial aerial springs supply the habitat systems which result from the environmental knowledge based on hydrogenesis, or water production. The method of interpreting towns based on the hydrogenesis and on the mangement of the local resources is an important means of understanding the settlements and express a meaning able to go beyond the aim of simple historical research.
General characters description and diffusion
The phenomenon of hidden precipitations is of primary importance in the ecology of the desert and allows gazelles to drink by licking the night dew off stones which are steeped in moisture, while lizards and beetles get the water ration they need to survive from the water contained in the air. Because of the temperature range from night to day that can exceed 60 degrees, there is a lot of night condensation on the ground that wets the sand. This wet sand is dried by the sun's rays and creates a hard crust which typically cracks when trod upon. If the hidden precipitations are properly managed, then they can form sizeable water reserves. Hydraulic arrangements such as mounds of stones can then collect the water vapour from the air and preserve it in the subsoil before it fades away at the first light of dawn. Under some circumstances, four centimenters cubed of water can be collected in the desert at night over a surface area of only one square meter. Some of the foggara networks, which are typical of Touat, are fed in this way. (Gauthier, 1928). The mounds of stones work both during the night and during the day. Under the boiling sun the wind carries traces of moisture and seeps into the interstices of the mounds of stones where the internal temperature is lower than the outside temperature becuase it is not exposed to the sun or becuase it has an underground room. The fall in temperature causes the condensation of the drops, which are either soaked up by the soil in the case of the walls or fall down into the cavity. The water accumulated finds further moisture and coolness, this improving the efficiency of the condensation construction. During the night, the process is reversed and condensation occurs outside, even though the results are the same. The external surface of the rocks is cooler and condenses moisture so that dew settles on the surface; the dew slides into the interstices and is collected in the underground room. This process is used all over the Murgia highland, in the regions of Apulia and Lucania, to supply water by means of dry walls and blocks of limestone. The quantity of water supplied is only apparently irrelevant. However, it is of great importance because it allows plants to exploit the smallest quantities of humidity able to overcome circumstances of water urgency. Therefore, its function is essential to maintain plants on the soil in lack of rain and irrigation. techniques deriving from these practices are now used in the desert of Sahara and in Namibia.
Advantages and sustainability
Hidden preciptations and hydrogenesis is achieved with deep knowledge of water management and is used to sustain populations of people and the process which are vital to life.