How do jetties help keep tidal inlets open for navigation?

Jetties are engineering structures designed to maintain navigable channels at tidal inlets, river mouths, and harbour entrances. They function primarily by "training"—or confining and directing—the flow of water.1

By narrowing the entrance, jetties concentrate the current, which promotes scour. This process helps remove sediment and prevents the channel from becoming blocked by silt or sand deposits. Additionally, these structures extend into deeper water where currents naturally slacken, ensuring that transported material is deposited away from the navigation path.1

Beyond managing sediment, jetties protect these entrances from the disruptive effects of wave action and littoral currents. When constructed in pairs, they create a stable, protected corridor that allows vessels to safely navigate through tide-influenced areas.1