The Nazca people built an extensive system of aqueducts in order to irrigate their crops. The area they lived in is extremely dry, rocky land with little to no surface water, and virtually no precipitation. It rains for approximately a half hour every two years. This forced them to dig down to the water table. They then dug tunnels to direct the flow of water to where they needed it. The holes down to the water have spiral walkways, which were possibly used to water their livestock, or make it easier to carry water out.