Aqueducts

An aqueduct is an watercourse constructed to carry water from a source to a distribution point mainly through the use of gravity and the flow of the water. The simplest aqueducts are small ditches cut into the earth. While ancient aqueducts were constructed above the ground, modern aqueducts may use pipelines and tunnels.

The famous aqueduct bridges

There is one problem with transporting water via an aqueduct. You can’t always control the terrain. Let’s say there is a valley in the path of an aqueduct between the source and the destination. How do we solve this problem?

One way of solving it is by building an inverted siphon.

_{Image attribution - DieBuche/ CC BY-SA 3.0}

An inverted siphon works by connecting pipes between the entry and exit points. The pipeline forms an U shaped structure. As the water enters the pipe it gains pressure due to gravity. The increased pressure is sufficient to lift the water back up and to the other side of the valley. The inverted siphon will work as long as the entry point is higher than the exit point.

However during ancient times it was not easy to construct inverted siphons. So to solve this problem Romans used bridges. They created the famous tall arched bridges for the water to flow continuously through a valley.

_{Image attribution - Benh LIUE SONG/ CC BY-SA 3.0}

Modern day uses

Aqueducts are still very much in use today. For example one of the world’s largest aqueduct, Catskill Aqueduct, which was constructed around 1910 is still in use today and suplies 40% of New York city’s total supply.