Lake water temperature

Background information

The water temperature at 1 meter depth depends mainly on the air temperature and water circulation. The level of the lake is also influenced by the weather: when it is warm, water evaporates and the level falls; when it rains, the level rises. Changing water temperatures and levels in a lake can affect the seasonal mixing of a lake, which in turn affects the surface temperature, but also the whole habitat in the lake. The lake system interacts with each other.

Description of the results

The average annual temperature of Lake Kaltern, a lowland lake, has remained relatively constant in recent years. As it is very shallow, it has a lower heat storage capacity and therefore fluctuates more strongly throughout the year. The highest temperature recorded in the last decade was 29.2°C on 5 August 2017. The mean temperature of Lake Kaltern/Caldaro remaines without any significant trend.

Lake Antholz/Anterselva lies at a higher sea level and is deeper. Its average daily water temperature is therefore lower. The highest temperature of the last decade was recorded in Lake Antholz/Anterselva on 5 August 2018 with 17.2 °C. Its mean average temperature decreased slightly between 2014 and 2025, which could be due to the fact that the series of measurements for this lake is quite limited.

Rising water temperatures can reduce or even limit bathing quality. Bathing can be harmful if cyanobacteria - colloquially known as blue-green algae - proliferate. Water quality and freshwater habitats are also adversely affected by warmer water temperatures. In addition, the toxicity of pollutants (e.g. heavy metals) increases, which has a negative impact on fish fauna and other freshwater species (1). Lake Kaltern/Caldaro in the lowlands is therefore more at risk than the cooler Lake Antholz/Anterselva in the mountains.

Method

The temperature of the lake is measured once an hour by means of a thermometer at a depth of about 1 meter.

Sectors affected

• Health

• Flora and Fauna

• Biodiversity

Related indicators

Further research at Eurac Research

 Current projects

• CLAIMES : https://www.eurac.edu/en/institutes-centers/institute-for-alpine-environment/projects/claimes und https://www.uibk.ac.at/projects/claimes/

• CHANGELAKE https://www.eurac.edu/en/institutes-centers/institute-for-alpine-environment/projects/changelake

Scientific presentations by Eurac Research

An integrative approach to evaluate ecosystem services of mountain lakes
Ebner M, Fontana V, Schirpke U, Pritsch H, Ohndorf M, Tappeiner U, Kurmayer R (2021)

Presentation/Speech. Conference: 12th Symposium for European Freshwater Sciences | Dublin/online | 29.7.2021 - 29.7.2021

Reference

1) Van Vliet Michelle T. H., Franssen Wietse H. P., Yearsley John R., Ludwig Fulco, Haddeland Ingjerd, Lettenmaier Dennis P., Kabat Pavel, 2013: Global river discharge and water temperature under climate change. Global Environmental Change 23:450-464 http://dx.doi.org

Contact

Eurac Research: Roberta Bottarin, Institute for Alpine Environment

Data provided by Landesagentur für Umwelt und Klimaschutz of the Autonomous Province of Bolzano, Biologisches Labor