Surface seiches in lakes of complex geometry

Abstract

In lakes of small to medium size, the characteristic frequencies of free oscillations of the water surface (seiches) depend only on the basin geometry. In irregularly shaped basins, such as dendritic reservoirs and multibasin lakes, these characteristic frequencies are not easily determined with simple formulas. Clear Lake, a multibasin lake in Northern California, is presented here as a case in point. The signature of the seiches in Clear Lake were only revealed after solving the eigenvalue problem governing the structure and frequency of seiches derived from the linear and frictionless depth-averaged shallow water equations in a nonrotating frame.