Richard Dallison
Studied catchments and hydropower abstraction locations.
Dŵr Uisce research conducted by academics in our Bangor team, and published last month in the journal Renewable Energy, has used hydrological modelling to characterise and quantify the potential implications of worst-case future climate change on river systems across the British Isles. The work uses the EXP-HYDRO hydrological model to project daily streamflow in 585 catchments between 2021 and 2080. The analysis has characterised changes in future average streamflows under pessimistic global emission forecasts (Representative Concentration Pathway 8.5), using the latest projections from the UK Met Office. These streamflow projections have then been used to estimate future water abstraction at 531 hydropower locations in a subset of 178 catchments, with power generation estimations subsequently being made.
Projected trends in annual average streamflow 2021-2080.
In terms of streamflow, seasonal trends generally have a larger magnitude of change than those seen in annual averages. These seasonal trends can be seen as an exacerbation of current streamflow patterns, particularly for the island of Ireland and western areas of Great Britain. In these areas especially, periods of higher flow presently, winter and spring, are increasing, while present periods of lower flow, summer and autumn, are declining. However, in central and south-eastern England, declines in winter and spring streamflows are projected. At an annual perspective, this leads to an overall decline in average streamflows across much of eastern, central, and southern England, while increases are seen along the west coast of Great Britain. On the island of Ireland however, the predominately negative trends in annual average streamflow are likely caused by the decreases in summer and autumn streamflow being larger in magnitude than winter and spring increases.
Due to these projected future streamflow patterns, similar regional variations in future annual abstraction potential are seen. These changes are however also influenced by nation-specific abstraction licence conditions and variations in regional climate forcing. Variations in abstraction licence conditions mean that even if catchments in different nations display similar streamflow alteration, the availability of water for abstraction, and therefore generation potential, may still differ. In general, there is also a reduction across the two islands in the number of days per year that abstraction for hydropower will be possible, with the only exceptions being schemes in northwest Scotland and the Lake District.
Change in projected future annual total abstraction (left) and number of days when abstraction is possible (right) at studied hydropower abstractions. Size and shade of triangles represent magnitude of change (larger and darker equals greater change), colour and orientation of triangles represent trend direction (blue increasing, red decreasing).
In terms of power generation, this has been calculated for Great Britain and the island of Ireland individually, owing to the energy network systems in place. Results project an annual increase of 6.2% in power generation from run-of-river hydropower generation for Great Britain, when comparing the 2021-29 average to the 2072-80 average. This trend is driven by large increases in Scotland in winter and spring, which outweigh reductions seen in the summer and autumn in England in particular. For the island of Ireland, a 1.4% decrease is seen in annual power generation when comparing the same time periods, driven by large summer decreases and smaller winter increases.
The results demonstrate that although perceived to be a region abundant in water resources, the British Isles will not escape the impacts of climate change induced streamflow reductions, especially in summer and autumn. The exaggeration of current seasonal streamflow patterns will require careful management moving forward for sectors such as hydropower, with future schemes needing to be designed to make best use of future flows.
The full open-access article can be found at https://doi.org/10.1016/j.renene.2023.03.021, while more information on the implications of the climate change work being conducted by the Dŵr Uisce Project can be found on the Future Water Resources page of our website.