First Arch Dam in the World

Which is the First Arch Dam in the World?

The world’s first Arch Dam- ‘Glanum Dam’, was located on the south west of the French town of Saint-Reme-de-Provence. The dam was also called as ‘Vallon de Baume Dam’ and was built around 1st century BCE to supply water to the ancient Roman town of Glanum. The location of the dam at a narrow gorge (The Gorge of Peyrou) between the hills of Les Alpilles provided an ideal location for the construction of an Arch Dam.

Though the dam was damaged during the construction of a modern dam at same place in 1891; it is established beyond doubt that the Glanum Dam was the first ever known dam of its kind.

Location of the Glanum Dam

The site of the Glanum Dam is located at a distance of 1 km south of the town of Saint-Reme-de-Provence in south west France. The dam was built on a narrow gorge called the Gorge of Peyrou, that cuts through the hills of Les Alpilles; a small range of low mountains in southern France.

The town of Saint-Reme-de-Provence is north to the Alpilles and to the Glanum Dam’s site; and both are almost at an approximate distance of 20 km (12 miles) from the Avignon town. Avignon has an airport and is well connected with Saint-Reme by roads and highways.

Details of the Dam

The Glanum Dam is known to be the oldest Arch Dam built around 1stcentury AD by the Romans to supply water to the ancient town of Glanum; one of their early settlements. The dam was built on a narrow gorge between Les Alpilles hills just south of Saint-Reme.

The constraint of space in the gorge and the scarcity of construction materials at site, provided an ideal location for an Arch Dam; as they are suitable for narrow spaces and require considerably low construction materials than a full fledge masonry dam.

An Arch Dam is a basically a curved dam that is curved upstream and is thinner than the gravity dams. The dams are designed as such that hydraulic pressure of the stored water pressing against the curved surface, strengthen the structure and also the abutments cutting inside the hills.

The Glanum Dam is reported to be 6 mtr (20 ft) high with a crest length of approximately 9 mtr (30 ft). The dam consisted of two parallel curved masonry walls around 1 mtr thick and space of 1.5 mtr (15 feet) between them.

The masonry walls were built of stones secured with crampons and the joints were made waterproof by using Cordon joints. The 1.5 mtr gap between the masonry was filled with stones and earth.

The dam was designed in such a way that the pressure of the water stored strengthens the masonry as well as the foundation and abutments cutting inside the hills on both the sides. It was surrounded by cliffs and valleys aiming for the collection of rain water in form of surface run off.

The dam had been a true architectural marvel with a width of only 3.5 mtr and located between two hills across a very narrow gorge.

The Discovery and History

The remains of the Glanum Dam were discovered by Esprit Calvet (1728-1810) in 1763. Calvet was a physician and a collector (by hobby) belonging to the town of Avignon in south east France.  The dam was built to supply water to the nearby town of Glanum by nearly 500 mtr long aqueduct built especially for the purpose.

Glanum was a fortified town built by Indo-European people also known as Salyes founded in the 6th Century BCE. Glanum officially became a Roman city under Emperor Augustus’ around 27 BCE, but the town didn’t survive the collapse of the Roman Empire and was abandoned in 260 CE. During the Roman Empire the town saw massive infrastructure developments by construction of monuments, sewers, temples also dams and aqueducts to supply water to the town for domestic purposes.

It was among these ruins of the town that Esprit Calvet discovered the remains of the Glanum Dam in 1763.

The Lake and the Modern Replacement of Glanum Dam

The ancient Glanum Dam was destroyed in 1891 when a modern Arch Gravity Dam was built at the same place. The dam impounds ‘Vallon De Baume’ (French) or the ‘Valley of Balm’ resulting in a small reservoir with a capacity of 80000 cubic meters, locally known as ‘Lac du Peirou’. The lake provides a beautiful outing to the locals and is quite popular among them. The way to the lake is south of Saint-Reme in the direction of Glanum.