Temperature is one of the key physical parameters influencing the chemical and, above all, biological processes in a watercourse.
It affects all metabolic processes, the duration, course and rate of growth, and the composition of biotic communities. The viability and activity of aquatic organisms are dependent on certain temperature limits and optima. Knowledge of temperature dynamics thus represents a valuable interpretative tool.
The FOEN temperature monitoring network provides a basis for assessing the effectiveness of Swiss environmental protection legislation (Water Protection Act/GSchG and Water Protection Ordinance/GSchV). It also facilitates causal analysis (e.g. thermal power plants, anthropogenic heat inputs/withdrawals, water management interventions, climate trends).
In cooperation with cantonal and national agencies and research institutes (cantonal water protection agencies and fishery authorities, MeteoSwiss, FOEN, Eawag, etc.), impacts on organisms (e.g. fish) can be studied. To achieve these goals, selected stations of the FOEN network are used either for long-term monitoring or for short-term measurements prompted by specific concerns. Particular attention is paid to the evaluation of data and to the establishment of links with other environmental monitoring programmes.
The FOEN temperature monitoring network is confined to watercourses, with efforts being made to ensure that measurements performed on one bank yield results that are representative of the entire cross section. The network comprises about 70 stations - a total sufficient to address most of the specified goals. Future evaluations will indicate whether further expansion of the monitoring network is required.
The monitoring stations are all equipped with a temperature probe, transducer and data logger. The data recorded by the logger is transmitted to the query centre via modem. The latest data can be consulted online or accessed on a mobile phone via SMS. Temperature data is published online, where monthly and yearly averages are presented in tabular form, together with maximum and minimum values, both for the year under review and for the entire measurement period. Analyses of the temperature data are also published in the Hydrological Yearbook.
Swiss lake temperature monitoring program (PDF, 2 MB, 01.02.2019)Commissioned by the FOEN
Last modification 19.11.2019