Surface Seiche Formation on a Shallow Reservoir in Complex Terrain

Abstract

This study presents field observations and numerical modeling of surface seiche formations on a shallow reservoir in a complex terrain (Rules Reservoir, Spain). The influence of the surrounding topography on the atmospheric loading (barometric pressure and wind speed) is investigated, with the associated atmospheric-hydrodynamic coupling. During a 13-day field study, maximum free surface oscillations of 4 cm were recorded after the passing of a short duration storm (<5 min), which included a peak wind gust of 22 m/s. Observations also present evidence of resonant excitation of the free surface caused by high-frequency microscale harmonics (<10 min) in the atmospheric forcing. Resonant excitation caused by harmonics in the atmospheric forcing is significant for small reservoirs situated in regions of complex terrain where topographical obstacles modify the flow patterns in the near-surface boundary layer, generating eddies with harmonics in the microscale range of the atmospheric forcing spectrum. Harmo...