Seiche

A seiche is a standing wave in an enclosed or partially enclosed body of water. Seiches can occur in lakes, reservoirs, harbors, and even swimming pools. Unlike tsunamis, which are caused by earthquakes or other seismic activity, or tides, which are caused by gravitational forces, seiches are typically triggered by meteorological conditions such as strong winds, atmospheric pressure changes, or seismic activity that is local but not necessarily large enough to generate a tsunami.

The oscillation of water in a seiche occurs at a specific resonant frequency, which is determined by the physical dimensions of the basin. The period of oscillation is related to the length and depth of the water body. Longer and deeper water bodies tend to have longer seiche periods.

Seiches manifest as rhythmic changes in water level, similar to a sloshing motion. The amplitude of a seiche can vary from a few centimeters to several meters, depending on the size and shape of the basin and the strength of the triggering force. While often subtle, large seiches can cause significant currents and localized flooding.

Seiches are characterized by one or more nodes, which are points where the water level remains relatively constant, and antinodes, where the water level fluctuates the most. The simplest seiche, known as a uninodal seiche, has one node in the middle of the basin and two antinodes at the ends. More complex seiches can have multiple nodes and antinodes.

The study of seiches is important for understanding the dynamics of enclosed water bodies and for predicting and mitigating potential hazards associated with large-amplitude seiches. Seiches are also relevant to water quality, as they can influence the mixing and transport of pollutants within a water body.