Adduction may consist of one or more pressure pipes, in which case it is referred to as a tunneling tunnel, or from adductor channels, consisting of free-flow channels. Free-floating channels are used when an important amount of water (about 1000 l / s) is to be conveyed, not so much for civil use, as for irrigation or for the supply of hydroelectric plants. The pipes are used for smaller capacities (30-200 l / s) and above all for civil use. From the design point of view, the solution of the drainage pipes is more complex and two typologies, gravity works and pumping works can be distinguished. The former use a natural geodetic altitude and does not imply any energy expenditure, while the latter must be equipped with a pumping plant, therefore, in addition to the cost of construction, they will also incur operating costs.
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