Water temperatures in the headwaters of the Volga River: Trend analyses, possible future changes, and implications for a pan-European perspective

Water temperature is a physical property influencing abiotic and biotic parameters in an aquatic ecosystem. In different Central European rivers and lakes, a general trend of water temperatures in the range of +0.05 to +0.8 degrees C per decade was identified. Our case study analyses whether similar patterns apply to the headwaters of the Volga River, in the East European plain. Based on a dataset of water temperatures for 2008-2015, we investigated the spatial and temporal distribution of water temperature along the Tudovka River and estimated backward as well as predicted future changes from development scenarios throughout the 21st century. Stochastic models were applied to track trends and variations in water temperature. Furthermore, the correlation between water temperature and air temperatures was used to model historical water temperatures and to predict possible changes in the future, under the effects of climate change. Based on climate change scenarios, an increase of the mean water temperatures as well as changes regarding the ice cover can be expected until the end of this century. The conditions described for the headwaters of the Volga River system represent a valuable dataset for medium and large rivers in the East European plain and serve as a basis for future management.