The Mixing Regime and Turbidity of Lake Banyoles (NE Spain): Response to Climate Change

• Published in: Water (Basel) Vol. 12; no. 6; p. 1621
• Main Authors: Serra, Teresa, Pascual, Josep, Brunet, Ramon, Colomer, Jordi
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01-06-2020
• Subjects: 21st century; Aquatic ecosystems; Aquifers; Basins; Climate change; Climatic changes; Environmental aspects; Epilimnion; Freshwater lakes; Global warming; Groundwater; Groundwater recharge; hydrothermal turbid plumes; lake mixing regime; Lakes; Productivity; Rainfall; Recharge areas; Sediments; Stratification; Summer; Surface water; Trends; Turbidity; Water temperature; Spain; Iberian Peninsula; Lake Banyoles
• ISSN: 2073-4441; 2073-4441
• DOI: 10.3390/w12061621

This study analyses the water temperature changes in Lake Banyoles over the past four decades. Lake Banyoles, Spain’s second highest lake, situated in the western Mediterranean (NE Iberian Peninsula). Over the past 44 years, the warming trend of the lake’s surface waters (0.52 °C decade−1) and the cooling trend of its deep waters (−0.66 °C decade−1) during summer (July–September) have resulted in an increased degree of stratification. Furthermore, the stratification period is currently double that of the 1970s. Meanwhile, over the past two decades, lake surface turbidity has remained constant in summer. Although turbidity did decrease during winter, it still remained higher than in the summer months. This reduction in turbidity is likely associated with the decrease in groundwater input into the lake, which has been caused by a significant decrease in rainfall in the aquifer recharge area that feeds the lake through groundwater sources. As a unique freshwater sentinel lake under the influence of the climate change, Lake Banyoles provides evidence that global warming in the western Mediterranean boosts the strength and duration of the lake’s stratification and, in response, the associated decrease in the turbidity of its epilimnion.