bisses

Bisses are traditional gravity-fed irrigation channels found in the Swiss Alps, especially in the canton of Valais and other French-speaking regions. They carry water from rivers, streams, or glaciers to agricultural fields on hillside terraces, enabling irrigation without pumps. The channels are typically narrow and stone-edged, often accompanied by walkways made of wood or stone for maintenance and inspection.

The construction of bisses dates from medieval to early modern periods, developed to support settlement and farming on steep terrain. Water rights and communal management were important, as landowners shared the use and upkeep of the network. Over centuries, new bisses were added to reach additional fields, and old sections were repaired or rerouted to respond to changing agricultural needs. The system reflects a cooperative approach to land and water use in mountainous landscapes.

Construction and operation rely on gravity to move water along a gentle down-slope gradient. Water is diverted at source by small weirs or gates and then travels through stone-lined troughs or channels that may run along walls, under ledges, or across open slopes. Some sections include covered troughs, while others are open. Maintenance involves repairing banks, lining, and control structures, and ensuring that flows to downstream fields remain adequate during varying seasonal conditions. The network often integrates with terraces and field boundaries, feeding multiple plots from a single headwater.

Cultural significance and preservation: bisses are emblematic of traditional mountain agriculture and communal water management. Many sections are preserved as cultural heritage and are popular for hiking, accompanied by interpretive signs. While some ongoing irrigation remains, others function primarily as historical or scenic features, reflecting the region’s agrarian past.