Variability and alterations of German river water temperatures
Eglinski, Christina (2023)
Diplomityö
2023
School of Engineering Science, Kemiantekniikka
Kaikki oikeudet pidätetään.
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe2023072490921
https://urn.fi/URN:NBN:fi-fe2023072490921
Tiivistelmä
In recent years, anthropogenic climate change became a major global concern. Studies indicate that the earth's increased atmospheric temperature is warming streams and rivers, affecting local ecosystems and thereby resources.
Temperature is a central variable for fundamental aquatic processes like oxygen dissolution or metabolic rates and determines the ecological niches. Temperature hence influences river ecosystems on all scales, from the molecular level to community composition. However, apart from air temperature, river temperatures are affected by numerous parameters and long-term, comprehensive studies on river water temperature dynamics are scarce.
This study examines Germany-wide thermal stream measurements, collected between 1981 and 2019 in a consistent framework to assess trends in river water temperatures and their dependence on spatial characteristics. In doing so, long-term mean trends are quantified on a national scale under consideration of seasonal differences and topographic as well as geographic variables such as stream order, altitude and distance to urban areas, providing an improved understanding of spatial drivers in river water temperature dynamics.
The calculated annual trends indicate an average water temperature increase of 0.25°C ±0.28°C/decade with autumn exposing a particularly high inclination of 0.43 ±0.49°C /decade on a seasonal scale. Latitude, longitude and baseflow index expressed the highest correlations to the determined trends over all analyses. However, fall presented exceptional results again. There, precipitation, latitude and solar radiation resulted in the highest explanatory coefficient values of the entire analyses.
The results aid with predicting future trends and thereby serve as the basis for preventive measurements in river-, resource-, and risk management.
Temperature is a central variable for fundamental aquatic processes like oxygen dissolution or metabolic rates and determines the ecological niches. Temperature hence influences river ecosystems on all scales, from the molecular level to community composition. However, apart from air temperature, river temperatures are affected by numerous parameters and long-term, comprehensive studies on river water temperature dynamics are scarce.
This study examines Germany-wide thermal stream measurements, collected between 1981 and 2019 in a consistent framework to assess trends in river water temperatures and their dependence on spatial characteristics. In doing so, long-term mean trends are quantified on a national scale under consideration of seasonal differences and topographic as well as geographic variables such as stream order, altitude and distance to urban areas, providing an improved understanding of spatial drivers in river water temperature dynamics.
The calculated annual trends indicate an average water temperature increase of 0.25°C ±0.28°C/decade with autumn exposing a particularly high inclination of 0.43 ±0.49°C /decade on a seasonal scale. Latitude, longitude and baseflow index expressed the highest correlations to the determined trends over all analyses. However, fall presented exceptional results again. There, precipitation, latitude and solar radiation resulted in the highest explanatory coefficient values of the entire analyses.
The results aid with predicting future trends and thereby serve as the basis for preventive measurements in river-, resource-, and risk management.