Changes in river flows, especially extreme high and low flows, could be a particularly important impact of climate change in terms of the hazard to people and the environment. Here, a national-scale grid-based hydrological model is applied, with ensembles of global and regional climate projections from UK Climate Projections 2018, to investigate the potential future changes in both floods and droughts in a consistent way across the whole of Great Britain (gauged and ungauged locations). Using hydrological model outputs for the climate projection ensembles, a clustering technique is applied to highlight ‘typical’ sets of changes in individual indicators of floods or droughts, but also to look at concurrent changes in pairs of flood and drought indicators. The results for regions across the country generally indicate decreases in low flows combined with increases in high flows up to the end of the 21st century. There is significant variation in results for different regions, with those to the south/east tending to show greater decreases in low flows and a greater range of uncertainty in the projections for high flows. A grid-based cluster analysis also shows potentially important variation within regions, likely related to catchment properties. The potential future changes in derived climate hazards, such as the frequency or severity of floods and droughts, is a key piece of information required for adaptation planning, and the consideration of potential concurrent changes in a range of related hazards/risks, rather than viewing each in isolation, could be vital to avoid maladaptation.

就人类和环境的危害而言，河流流量的变化，特别是极端高流量和极低流量，可能是气候变化的一个特别重要的影响。在这里，应用了基于国家规模的基于网格的水文模型，并结合了《 2018年英国气候预测》中的全球和区域气候预测，以一致的方式调查了整个英国的未来洪水和干旱的潜在变化（规范和未规范的位置）。将水文模型输出用于气候预测集合，使用聚类技术突出显示洪水或干旱的单个指标的“典型”变化集，同时查看洪水和干旱指标对中的同时变化。全国各地区的结果通常表明，到21世纪末，低流量的减少与高流量的增加相结合。不同地区的结果差异很大，南部/东部地区的趋势倾向于显示低流量下降幅度更大，高流量预测的不确定性范围更大。基于网格的聚类分析还显示了区域内潜在的重要变化，可能与流域特性有关。衍生气候危害的潜在未来变化，例如洪水和干旱的频率或严重程度，是适应规划所需的关键信息，也是对一系列相关危害/风险的潜在同时变化的考虑，而不是查看彼此隔离，对于避免适应不良可能至关重要。