Experimental researches on water recirculation for irrigation and environmental purposes.

The recent long periods of drought in the Padana plain, in northern Italy, determined a shortage of water for irrigation and some serious environmental problems such as salt water intrusion in rivers and in coastal aquifers, with consequent further difficulties for agriculture. Since these long dry periods seem to be not fortuitous but representative of a well defined climatic trend, new principles should be adopted, if possible, for design and management of plain catchments, based on rainwater capturing and recirculation with both environmental and irrigation purposes. This kind of experience has been put in activity in the Vallevecchia basin, about 700 hectares wide, located in province of Venice, along the Adriatic Sea. The basin has been equipped with many hydraulic structures finalized to water recirculation, mainly consisting in a storage basin, a series of channels and a pipe to convey the water and a pumping station for storage purposes. The main hydraulic and environmental parameters are regularly monitored in different points inside the basin. The available experimental data clearly demonstrate the effectiveness of the artificiallyinduced water recirculation from both agricultural and environmental points of view.