Séquia Major (Main Canal) of the Ebro Nature · Xerta, Baix Ebre, Tarragona Image of Xerta, not of the place itself. The Séquia Major de l'Ebre rises at the Xerta weir, located about 15 kilometres upstream from Tortosa and 3 kilometres from the town of Xerta, and is one of the most important historic hydraulic features of the río Ebro. The 55-kilometre main canal was built between 1856 and 1857 by the Reial Companyia de Canalització de l'Ebre, under the concession granted in 1849 to the Frenchman Isidore Pourcet, and is completed by 49 kilometres of secondary channels totalling more than 300 kilometres of irrigation network. With a capacity of about 30 cubic metres per second, it irrigates 12,096 hectares of the Baix Ebre and Montsià, mainly around Amposta, of which 85% is devoted to rice cultivation. Photo: Jorge Franganillo (CC BY 2.0) What to see and do in Xerta