||HUMIDITY CONDENSATION TECHNIQUES
Definition characters description and diffusion
In the south of Italy, the climate ranged from freezing winters to scorching summers. Water shortage fostered practices for meteoric water collection and underground storage. Caves keep a constant temperature throughout the year and are the ideal shelters for human beings and animals, for the storage of grain and mainly of water. The latter is the most precious underground resource: water dripping from walls, seeping out from the rocks, forming puddles, and, though always drawn, ‘miraculously’ keeping at a steady level, just as in the cave of Manduria described by Pliny (Natural History, II, 226). Each underground cavity can be related to water harvesting techniques or to water-related rites.
General characters description and diffusion
Evidence of such practices, dating back to the 4th millennium (Tiné and Isetti, 1980), were found in the Grotta Scaloria, along the Gargano slopes, in Apulia, in the form of ceramic pots, which were placed under stalactites to harvest dripping water. In some caves, vapour-laden air caused by the heat coming up from the magma under the earth’s crust are condensed along the walls to produce water. This method that was described by the Latin writer Vitruvius (De Architettura, VIII, 4) can be seen among the ruins of the Roman town of Tiddis, in North Africa. In Eritrea, on the highlands and in the region of Afar, the fumaroles, which are called boina (Dainelli and Marinelli, 1912) by the Danakils and originate from the faults of the Rift Valley, produce moisture that is harvested in the open air by means of a device made of tree branches. This technique involves building hut-like structures with conical roofs made from plants right over the volcanic fumaroles. Vapour rises up to the branches where it condenses into water and drops down. Then it is collected in basins. A similar method is used to collect dew from the straw and leaves covering deep trenches dug into the ground. This technique was applied by the Nabateans in the Negev Desert and in the underground Roman town of Bulla Regia in Tunisia (Pignauvin, 1932).
Advantages and sustainability
Condensation of humitidy can lead to very important water sources that are necessary to human life and other vital processes.