Peak Runoff Timing Is Linked to Global Warming Trajectories

The earth's hydroclimate is continuing to change, and the corresponding impacts on water resource space‐time distribution need to be understood to mitigate their socioeconomic consequences. A variety of ecosystem services, transport processes, and human activities are synced with the timing of peak annual runoff. To understand the influence of changing hydroclimate on peak runoff dates across the continental United States, we downscaled outputs of 10 Global Circulation Models for different future scenarios. Our results quantify robust spatial patterns of both negative (up to 3–5 weeks) and positive (up to 2–4 weeks) shifts in the dates of peak annual runoff occurrence by the end of this century. In snowmelt‐dominated areas, annual maxima are projected to shift to earlier dates due to the corresponding changes in snow accumulation timing. For regions in which the occurrence of springtime extreme soil wetness shifts to later time, we find that peak annual runoff is also projected to be delayed. These patterns of runoff timing change tend to be more pronounced for projections of higher greenhouse concentration in the future.

地球的水文气候正在持续变化，需要了解其对水资源时空分布的相应影响，以减轻其社会经济后果。多种生态系统服务、传输过程和人类活动都与年径流量峰值的时间同步。为了解变化的水文气候对美国大陆峰值径流日期的影响，我们针对不同的未来情景对10个全球环流模型的输出进行了降尺度处理。我们的研究结果量化了到本世纪末年径流量峰值出现日期负向（多达3 - 5周）和正向（多达2 - 4周）变化的稳健空间模式。在以融雪为主的地区，由于积雪时间的相应变化，预计年最大值将向更早的日期转移。对于春季极端土壤湿度出现时间推迟的地区，我们发现年径流量峰值预计也会延迟。对于未来温室气体浓度更高的预测，这些径流时间变化模式往往更加明显。