Okay kiddo, so in ancient Sri Lanka, people needed a lot of water to grow their crops. But they didn't have modern tools to get water from rivers or lakes. So they came up with a very clever system called irrigation.
Think of it like a big straw that sucks water from one place and brings it to another. Instead of a straw, they dug deep channels or ditches called canals. These canals were filled with water from rivers or lakes and they flowed through the fields.
But the fields were not flat, they had lots of ups and downs. So they made small walls or dams called bunds. The bunds were built across the canals so that the water would stop flowing and gather in one place. This created a small pond of water.
Then they used smaller canals to bring the water to each field. They also used special tools called mattocks and hoes to dig holes in the ground where the water could seep in and water the plants.
The people in ancient Sri Lanka were very clever, they even built underground tunnels to carry water from one place to another. They called them Yodha Ela or warrior canal because they were built by skilled workers who were also warriors.
All these canals and tunnels made sure that the farmers had enough water to grow their crops. And because they were able to grow more food, they were able to trade it with other people for things they needed like clothes and tools.
So you see, irrigation in ancient Sri Lanka was a very important way for people to get the water they needed to grow their crops and live a good life.