How does surface/flood irrigation primarily move water across the land?

Surface or flood irrigation primarily relies on gravity to move water across the land. In this method, water is distributed over the soil surface and allowed to flow into the designated areas where crops are planted. The natural slope of the land facilitates the movement of water, allowing it to spread over fields and reach the root zones of plants without the need for mechanical assistance.

This approach is particularly effective in areas where the topography is conducive to gravity flow and can efficiently saturate the soil. The practices typically involve creating furrows, basins, or borders that help guide the water to where it is needed. Unlike pressurized systems, which require external energy sources and infrastructure, gravity-fed irrigation is simpler and often more cost-effective in suitable landscapes.

Other methods mentioned, such as pumps, underground pipes, or wind-driven systems, do not play a primary role in surface irrigation, reinforcing the truth of gravity's central role in this technique.