Recent years has seen a focus on river temperatures primarily in the context of climate change. Adding to the body of evidence available The James Hutton Institute (JHI) led by Rachel Helliwell (Senior Research Scientist) has recently completed an analysis of river temperature trends in the Spey based on historical angling records from Tulchan Estate. River temperatures have been collected on a daily basis by the estate ghillies with these data recorded in the angling records maintained on the estate. These records extend back over 100 years to 1912.
A factsheet on the analysis, including recommendations can be downloaded by clicking this link River Temperatures Factsheet.
The ghillies temperature records, and a model developed using a range of other datasets, show that the temperature of the Spey has risen significantly in recent decades. Factors contributing to this increase in river temperatures are thought to include rising air temperatures, decreased snowfall, earlier snow melt in the spring & reduced flow.
A range of recommendations to mitigate further rises in temperature are made including river restoration, riparian tree planting, flood management, abstraction control and protection of groundwater. This last point is often overlooked. Groundwater upwellings can provide thermal refugia wherever they occur. Technology such as thermal cameras on drones could now allow us to map where these upwellings occur.
The work of Marine Scotland Science (MSS) in this field is acknowledged , and rightly so. The established a network of temperature loggers across a range of Scottish catchments, including the Spey, by MSS has already produced a number of outputs including the development of riparian tree planting strategies to limit future temperature rises.