1,000-year-old Moorish Irrigation System Still Operating in Valencia

The centerpiece of Valencia's 183-year-old Mercado Central are its fruits and vegetables – plump, richly colored and all grown in La Huerta (L'Horta in Valencian), a patchwork of neat market gardens that fan out for 10 square miles around the city.  Valencia's incredible bounty of produce is grown in La Huerta each year, despite the fact that its fields enclose Spain's third-largest city. The secret is an ingenious maze of channels, ditches, weirs and floodgates invented by the region's Moorish rulers 1,200 years ago.

Eight main irrigation channels, or acequías, funnel water from the River Turia, which is then carried – by gravity – along a series of smaller branches, which distribute the water to thousands of tiny plots across the fields. The amount of water each plot receives isn't measured in terms of volume but rather on how well the river is flowing. The unit, known as a fila (from the Arabic word meaning "thread"), represents an individual's right to a proportion of the water over a period of time; the irrigation cycle usually lasts a week, but when the river's level is low, the cycle is extended.

It's an incredibly efficient system. Each plot receives the same access to water for the same amount of time, no matter where they are in the mosaic, and there are no water shortages, even in periods of drought. And the result is an incredibly diverse crop yield. Centuries-old local rice varieties grow in the fields around Lake Albufera, south of the city, while unique species like chufa, or tiger nuts (which are used to make the ice-cold milky Valencian drink of horchata), are sown in the north.

The whole process is held together by a unique social organization that has been governing La Huerta for more than 1,000 years. The Tribunal de las Aguas de la Vega de la València, or Water Court of the Plains of Valencia, was established around 960 CE and as such is officially the world's oldest judicial body. The tribunal is made up of eight farmers, elected representatives of the communities that work off each of the main irrigation channels, who meet to settle disputes outside the doorway of Valencia Cathedral every Thursday at noon.

It's quite a sight, with the men – they are all men – dressed in black smocks and seated in a semi-circle of leather-topped wooden chairs, where they enforce the rules of distribution. Water is the only issue up for debate, and according to María José Olmos Rodrigo, the Tribunal's secretary, the defendants are usually hauled before the court because "they've flooded a neighbor's field, taken water out of turn or haven't maintained their section of irrigation ditch correctly". Proceedings are in Valencian and are ruthlessly quick; all decisions are final.

"Production in La Huerta is basically intended for self-consumption and the local market," said Vicente Domingo, director of CEMAS. "Thanks to its unique structure, it has managed to survive over the centuries with the efforts of generation upon generation of farmers that have preserved this land despite the pressure of urbanization."