When considering a body of water in a large reservoir, how does the pressure gradient force interact with gravitational effects to maintain hydrostatic equilibrium?

In a large reservoir, the weight of the water pushes downward, creating a pressure that increases with depth. This increasing pressure produces an upward pressure‑gradient force that exactly balances the downward gravitational force at every depth. When these two forces cancel, the water remains at rest, a state called hydrostatic equilibrium. For example, at 10 m depth the pressure is about 100 kPa, and the pressure‑gradient force per unit volume equals the gravitational force per unit volume, keeping the water stationary. Thus, the pressure gradient and gravity together maintain a stable, non‑moving water column.