Author(s): C. Meruane; Y. Nino; R. Garreaud
Linked Author(s): Yarko Niño
Keywords: Thermo-hydrodynamics; Phytoplankton dynamics; Wind mixing; Lake Villarrica; Puelche; Foehn
Abstract: Lake Villarrica is located in south central Chile, at the foot of the Andes Mountain Range (38_o_ 18’ S, 72_o_ 05’ W). Its altitude is 230 meters above sea level, its surface area is 176 Km2 and its maximum depth is 167 m. The lake is regarded as monomictic and mesotrophic. Strong wind coming from the east is usually observed in the region. It corresponds to the kind of Foehn winds and is locally called “Puelche”. Three or four Puelche events typically occur during summer time, when the lake shows a strong thermal stratification. In the present paper, results of a field study and numerical simulations of the response of the thermohydrodynamics of the lake and phytoplankton productivity to the forcing induced by Puelche events are reported and discussed. The simulations were conducted using CE-QUAL-W2, a two-dimensional laterally averaged hydrodynamic and ecological model. Simulations show that Puelche events induce a rather important mixing of the surface waters, in agreement with observations during the summer 2004. Model results indicate that this mixing in turn increases productivity in the lake with respect to the situation in absence of this meteorological phenomenon, particularly when Puelche occurs at the end of the summer season, when phytoplankton biomass would otherwise be naturally declining.
Year: 2005