Lakes are often described as sentinels for climate change as they integrate changes in global and local climate as well as watershed properties and water transparency. Moreover, alpine lakes respond faster to changes in their catchments than low altitude lakes due to their small size, small catchment areas, and steep surrounding slopes. With accelerated changes in mountain climate, mountain lakes have become of increasing interest to scientists as predictors of changes in low altitude lakes. However, traditional one-dimensional models based solely on meteorologic conditions fail to represent alpine lake temperature cycles reliably. In contrast to low altitude lakes, energy balances in mountain lakes are highly impacted by catchment properties such as snow cover and inflow rather than direct fluxes with the atmosphere. An additional practical challenge comes from the lack of accessibility and harsh field conditions of these lakes. The evolution of mountain lakes in a changing climate is thus still unknown. This study quantifies the role of throughflow in the heat budget in various Alpine lakes in the French alps spanning from 2000 m to 3000 m a.s.l, in glacial and non-glacial watersheds using meteorological and water temperature data collected in the “Reseaux Sentinelle” Lakes in France. Our results highlight that changes in watershed snow cover and spring melt volumes must be included in the classical one-dimensional vertical description of the heat exchanges based on meteorological conditions to characterize the evolution of mountain lakes under climate changes.

Primary Presenter: Isabel Herr, University of Lausanne (isabel.herr@unil.ch)

Authors:

Marie-Elodie Perga,   ()

Damien Bouffard,   ()