Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/hess-2017-337
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
03 Jul 2017
Review status
This discussion paper is under review for the journal Hydrology and Earth System Sciences (HESS).
Tributaries affect the thermal response of lakes to climate change
Love Råman Vinnå1, Alfred Wüest1,2, Massimiliano Zappa3, Gabriel Fink4, and Damien Bouffard1,2 1Aquatic Systems Laboratory, Margaretha Kamprad Chair, École Polytechnique Fédérale de Lausanne, Institute of Environmental Engineering, Lausanne CH-1015, Switzerland
2Eawag, Swiss Federal Institute of Aquatic Science and Technology, Surface Waters – Research and Management, Kastanienbaum, Switzerland
3Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland
4Center for Environmental Systems Research, CESR, University of Kassel, Kassel
Abstract. Thermal responses of inland waters to climate change varies on global and regional scales. The extent of warming is determined by system-specific characteristics such as fluvial input. Here we examine the impact of ongoing climate change on two alpine tributaries, the Aare River and Rhône River, and their respective downstream, peri-alpine lakes: Lake Biel and Lake Geneva. We propagate regional atmospheric temperature effects into river discharge projections. These, together with anthropogenic heat sources, are in turn incorporated into simple and efficient deterministic models that predict future water temperatures, river-borne suspended sediment concentration (SSC), lake stratification and river intrusion depth/volume into the lakes. Climate-induced shifts in river discharge regimes, including seasonal flow variations, act as positive and negative feedbacks in influencing river water temperature and SSC. Discharge-dependent increase of river temperature in turn results in large seasonal shifts in warming of downstream lakes. Their hydraulic residence times control seasonal variations in climate-induced heating. Previous studies suggest that climate change will diminish deep-water oxygen renewal in lakes. We find that climate-related seasonal variations in river temperatures and SSC affect the rate of deep-penetrating river intrusions. Seasonal variations (with decreasing flows in summer and increasing flows in winter) determine water input reaching the deepest parts of lakes. The river-lake model results described here show an annual increase in deep-water renewal. This process may therefore counteract otherwise negative effects of climate change on deep-water oxygen supply in lakes. Our findings provide a template for evaluating the response of similar hydrologic systems to on-going climate change.

Citation: Råman Vinnå, L., Wüest, A., Zappa, M., Fink, G., and Bouffard, D.: Tributaries affect the thermal response of lakes to climate change, Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2017-337, in review, 2017.
Love Råman Vinnå et al.
Love Råman Vinnå et al.
Love Råman Vinnå et al.

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