Levada
Levada are artificial watercourses on the Portuguese island of Madeira that water is directed from the wetter areas in the north and center of the island's agricultural regions in the south. Since this often large distances must be overcome, a large part of the Levada runs with very low gradient. For these waterways overcome valleys and mountains, traverse the tunnel, crossing natural watercourses and also carry over bridges.
Today, the Levada be used for tourism except for the transport of water especially. On the track adjacent to the water paths trails are signposted in many places.
Geographical prerequisite for the construction of the Levada
The island of Madeira is divided by a mountain range which extends from east to west, in a southern and a northern half. For the eastern part of the mountain is characteristic that the massif very much more rugged north slopes than south and forms a natural barrier to the north and northeast winds. Therefore, this mountain range recorded increased rainfall - up to 2000 mm per year, with no pronounced dry season - while the south of the island may be six months dry (semi -arid ). Decreased duration of sunshine and lower temperatures also set the evaporation down on the north side of the island. These factors cause a large abundance of water in the north. Due to the extremely steep terrain of this wealth can there not be used agriculturally. On the dry south side with its gentle sloping hills on the other hand, there are a lot more growing areas. The water is so abundant there, where it can not be used accordingly. A geological condition further enhances this effect. Madeira geological structure has several oblique bearing strata of lava, slag, ash and tuff, which are separated by non-porous basalt reefs and conglomerate masses. The rain that seeps through the surface on these embeddings, seeks to drain the steepest path. Even precipitation, rain down on the southern slopes, flow mostly to the north. Most of these sources emerge at an altitude of 1500-1600 meters above sea level. That can bring problem of how the abundant water supplies ( one suspects 200 million m³ of water stored in the porous layers ) of the north to the south, was solved by the construction of the Levada. Today, virtually every field is the island in the low rainfall period, from April to October, watered by Levada.
The history of the Levada
In the 15th century, the first irrigation canals were built in Madeira. 1461, ie only 40 years after the colonization of the island, Prince Ferdinando certain that two men - the Hereus - should be entrusted with the distribution of water. 1485 then decreed King John II, when the Levada officer should assign the users the important wet. In 1493 he issued a law that no land owner could hinder the construction, repair or use of Levada. From 1650 bigger and wider channels were for the rapidly increasing consumption, especially for sugar cane cultivation and the water mills created. Arab and African slaves were forced to do the breakneck work at dizzying heights. The fate of the Moors, who had extensive experience in irrigation technology is likely to have contributed greatly to the development of the channels. As a result of stagnant trade in sugar is rarely reported after 1680, nor by the further expansion of Levada.
The Levada system today
If one asks about the extent of the irrigation system, so you can hear numbers 800-5000 km, depending on whether the small branches of the great channels that reach each field be counted or not. The youngest and most modern Levada Madeira is the only in 1966 was put into operation Levada dos Tornos. It has a length of 106 km and irrigates 9900 ha of land. At 16 km it leads through tunnels, the longest of which measures 5.1 kilometers. A power company is involved with in this Levada. A total of three power stations are operated with the water of Levada, before the water is supplied to the actual purpose of irrigation. Since the water must always flow smoothly, the Levada must be constantly maintained. Therefore, all Levadas are accessible, either on the Levadamauer or on a path next to the canal, the Passeio as levada. In the higher elevations to 700 m these routes serve the residents as footpaths to their homes. In wash-houses, the water is derived for the Planter, Children bathe in the Levada and occasionally the Levada serves as a transport route, such as for wood.