In hydraulic engineering, sluice gates are essential for managing water flow through channels, reservoirs, and irrigation systems. Sluice gates, acting as vertical barriers, regulate water by adjusting the gate's opening height, which changes the velocity and pressure of water flowing beneath the gate. Understanding the forces involved is crucial to designing sluice gates that can withstand dynamic pressure differences, especially when the gate is closed or partially open.

Key variables in analyzing sluice gate forces include the upstream depth z₁, and the downstream depth z₂. When the gate is closed, the water depth is greater on the upstream side, creating a significant pressure differential across the gate. This pressure difference produces a net force, which requires an anchoring system to keep the gate securely in place. The hydrostatic pressure exerted on the upstream side is proportional to the water depth and gravitational force, while the downstream pressure depends on z₂. The resulting pressure gradient across the gate creates a net force pushing against it toward the downstream side.

When the sluice gate is partially open, water flows beneath it, and Bernoulli's principle can be used to determine the downstream velocity, V_2.

Given the upstream and downstream depths, the principle relates the change in pressure due to differences in water height, allowing for calculating V₂ based on height differences and pressure gradients. This flow decreases the pressure exerted on the gate by allowing movement rather than accumulation, reducing the net force as water flows freely.

The total reaction force on the sluice gate is mainly influenced by the hydrostatic force from the upstream water column, which is at its highest when the gate is fully closed. As the gate opens and water flows beneath it, the reduction in pressure differential lowers the reaction force.