Aqueduct (water supply)

An aqueduct moves water.

It carries water from one place to another. It can be a long ditch. It can be a pipe. It can even be a tunnel under the ground.

People built these to help crops grow. They also use them to give water to big cities. This helps people have water to drink.

Some aqueducts use stone arches. These look like bridges. They carry water across valleys. This keeps the water moving to where it is needed. It is a smart way to move water far away.

An aqueduct is a way to move water.

It carries water from a source to a far place. This might be a river or a spring. People use them to water crops. They also use them to give drinking water to big cities.

Aqueducts come in many shapes. Some are just small ditches in the dirt. Others are large pipes. Some run through tunnels underground.

In ancient times, many people built them. The Romans built famous ones with stone arches. These look like bridges. They carry water across deep valleys.

In dry places, people used a special way called a qanat.

A qanat is a set of underground tunnels. They use vertical shafts, which are like deep wells, to reach the water. The water flows down these tunnels using gravity. This keeps the water cool and safe from the hot sun. This helps plants grow in dry lands. Today, we still build very big aqueducts. The Central Arizona Project is one of the largest in the United States.

It is 336 miles long.

An aqueduct is a special way to move water.

It carries water from a source to a place far away. This might be a river, a spring, or a reservoir. People build them to help crops grow through irrigation. They also use them to provide drinking water to big cities. Some aqueducts help areas that do not get much rain. Modern engineering uses many different structures for this job. These include pipes, ditches, canals, and even tunnels.

How does an aqueduct work? Most of them rely on something called gravity. This means the water flows downhill from the source to the destination. Engineers must plan a careful gradient, which is a slight slope. A steeper slope lets a small channel carry more water. However, water moving too fast can damage the structure.

Some systems use underground tunnels called qanats. These use vertical shafts, which look like deep wells, to reach water. This keeps the water from evaporating in the hot sun. In other places, people use pipelines to move water over hills.

Many different cultures built these systems long ago. The Assyrians built a limestone aqueduct in the 7th century BC. It was 80 km long to reach the city of Nineveh.

The Minoans on Crete used advanced systems around 2000 BC. In Persia, people began building qanats about 3000 years ago. The Nabataeans in Petra, Jordan, used pipes to move water through mountains. They even used dams to stop flood waters. In South America, the Nazca culture built puquios using stones. These stone systems are still used today.

Ancient Rome is very famous for its many aqueducts. They built them all over their empire, from Africa to Germany.

Some Roman aqueducts used stone arches to look like bridges. These bridges carried water across deep valleys. In Sri Lanka, the Yoda Ela canal was built in the 5th century AD. It had a very precise slope of only 10 to 20 cm per kilometer. The Aztecs in Mexico also had two aqueducts for their capital. One was the Chapultepec aqueduct, which was later rebuilt by the Spanish.

Today, we build even larger aqueducts to support huge populations. The United States has some of the largest systems in the world.

The Central Arizona Project is the largest and most expensive in the country. It stretches 336 miles from Parker, Arizona, to Phoenix and Tucson. The Colorado River Aqueduct is 242 miles long. It supplies water to the Los Angeles area. In China, the South-North Water Transfer Project connects the Yangtze River to Beijing. These massive projects show how much we still rely on moving water.

An aqueduct is a man-made watercourse designed to transport water from a source to a distant destination. The term comes from the Latin words "aqua," meaning water, and "ducere," meaning to lead or guide. These systems are essential for human civilization because they allow water to reach places that would otherwise be too dry. They are used for irrigation to help crops grow and to provide drinking water to large cities. In modern engineering, an aqueduct describes any system of pipes, ditches, canals, or tunnels used for this purpose.

Most aqueducts function by using the force of gravity to move water. For this to work, the destination must be lower than the water source, such as an upland aquifer. Engineers must calculate a precise gradient, which is a very slight slope. A steeper gradient allows a smaller channel to carry a larger volume of water. However, if the gradient is too steep, the fast-moving water can damage the structure. For example, a typical Roman aqueduct had a gradient of about 1:4800.

There are several different types of aqueduct structures used throughout history. The simplest form is an open channel, such as a small ditch cut into the earth. More advanced versions include rills, which are small, lined canals made of stone, brick, or concrete. These linings are important because they reduce water loss from absorption and increase durability. Another type is the pipeline, which is useful for moving water over hills. Pipelines also help prevent water loss from evaporation, freezing, or pollution.

Underground aqueducts are another specialized design, often used in hot, dry climates. In Persia and Oman, people constructed systems called qanāts or falaj. These consist of a series of gently sloping horizontal tunnels connected by vertical, well-like shafts. This design allows water to be delivered to the surface without the need for mechanical pumping. Because the water stays underground, it is protected from losing large amounts to seepage or evaporation. In Oman, there are three types of falaj: Daudi, Ghaili, which requires a dam, and Aini, which uses a spring.

Humanity has been building these systems for thousands of years. The Minoans on Crete likely used advanced irrigation and aqueducts around 2000 BC. As early as the 7th century BC, the Assyrians built an 80 km long limestone aqueduct to supply the city of Nineveh. This system included a 10 m high section to cross a 300 m wide valley. The Romans later perfected this technology, building aqueducts across their entire empire. Their stone bridges with multiple arches became so iconic that the word "aqueduct" is often used specifically to describe these bridges.

Different cultures developed unique solutions based on their environments. The Nabataeans in Petra, Jordan, used piping and dams to move water through mountains and gorges. In Peru, the Nazca culture built puquios, which are underground aqueducts made of intricately placed stones. These were likely built around A.D. 540–552 to respond to droughts. In Sri Lanka, the Yoda Ela canal was built in the 5th century AD with an incredibly precise gradient of only 10 to 20 cm per kilometer. Even the Aztecs in Mexico utilized aqueducts, such as the Chapultepec aqueduct, to water their capital city.

Modern aqueducts are massive engineering feats that support entire regions. In the United States, the Central Arizona Project is the largest and most expensive aqueduct. It stretches 336 miles from Parker, Arizona, to the metropolitan areas of Phoenix and Tucson.

The Colorado River Aqueduct is also massive, running 242 miles to supply Los Angeles. In China, the South-North Water Transfer Project aims to connect the Yangtze River basin to Beijing using three separate systems. These projects demonstrate how moving water remains a central part of global infrastructure.