Water movement through soil is primarily influenced by which of the following forces?

Water movement through soil is primarily influenced by gravity, which plays a significant role in determining how water percolates and drains through the soil profile. When water is applied to the surface of the soil, gravity pulls it downward, allowing it to move through the soil layers. This downward force is essential for the process known as drainage, as it helps to facilitate the flow of water through the pores between soil particles.

While other forces such as capillarity and hydrostatic pressure do affect water movement, gravity is the dominant force governing the downward flow. Capillarity acts to draw water upwards against gravity in small soil pores, and hydrostatic pressure can influence water movement in certain saturated conditions, but these forces are not the primary drivers of water movement. Instead, they modify or complement the effects of gravity in specific contexts. Understanding the role of gravity helps water operators manage irrigation, drainage systems, and groundwater sustainability effectively.