Set of blocks of four «Pro Patria – Valais bisses»

These historical irrigation channels tell the story of a traditional engineering method. The open water pipes are laid in the ground, cut into rock or suspended from steep rock faces, all to channel glacier water from the mountain streams to the pastures, fields, vineyards or orchards in the dry areas below, for instance to the dry landscape of the Lötschberg south ramp. To manage this area, bisses were built under the toughest conditions. One of these is the Gorperi, built in 1640, which carries water from the Baltschiederbach stream to the slopes around Eggerberg. Another example is the 14-kilometre long Grand Bisse de Lens. Despite the extremely difficult passages along sheer rock faces, it was constructed over the space of just two years in the 15th century.