Climate-driven changes in UK river flows: a review of the evidence

There is a burgeoning international literature on hydro-climatic trend detection, motivated by the need to detect and interpret any emerging changes in river flows associated with anthropogenic climate change. The UK has a particularly strong evidence base in this area thanks to a well-developed monitoring programme and a wealth of studies published over the last twenty years. This paper reviews this research, with a view to assessing the evidence for climate change influences on UK river flow, including floods and droughts. This assessment is of international relevance given the scale of the research effort in the UK, a densely monitored and data-rich environment, but one with significant human disturbances to river flow regimes, as in many parts of the world. The review finds that changes can be detected in river flow regimes, some of which agree with future change projections, whilst others are in apparent contradiction. Observed changes generally cannot be attributed to climate change, largely due to the fact that river flow records are limited in length and short-term trends are confounded by natural variability. A UK ‘Benchmark’ network of near-natural catchments is an internationally significant example of an initiative to enable climate variability to be discerned from direct human disturbances (e.g. abstractions, dam construction). Generally, however, the problem of attribution has been tackled rather indirectly in the UK, as elsewhere, and more efforts are required to attribute change in a more rigorous manner.