Abstract In this study, we investigate changes in future streamflows in California using bias-corrected and routed streamflows derived from global climate model (GCM) simulations under two representative concentration pathways (RCPs): RCP4.5 and RCP8.5. Unlike previous studies that have focused mainly on the mean streamflow, annual maxima or seasonality, we focus on projected changes across the distribution of streamflow and the underlying causes. We report opposing trends in the two tails of the future streamflow simulations: lower low flows and higher high flows with no change in the overall mean of future flows relative to the historical baseline (statistically significant at 0.05 level). Furthermore, results show that streamflow is projected to increase during most of the rainy season (December to March) while it is expected to decrease in the rest of the year (i.e., wetter rainy seasons, and drier dry seasons). We argue that the projected changes to streamflow in California are driven by the expected changes to snow patterns and precipitation extremes in a warming climate. Changes to future low flows and extreme high flows can have significant implications for water resource planning, drought management, and infrastructure design and risk assessment.

中文翻译：

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气候变暖下加利福尼亚溪流的新常态：潮湿的雨季和干燥的旱季

摘要 在这项研究中，我们使用从全球气候模型 (GCM) 模拟得出的经过偏差校正和路由的水流在两个代表性浓度路径 (RCP)：RCP4.5 和 RCP8.5 下研究加利福尼亚未来水流的变化。与以前主要关注平均流量、年度最大值或季节性的研究不同，我们关注流量分布和潜在原因的预测变化。我们报告了未来流量模拟的两个尾部的相反趋势：较低的低流量和较高的高流量，相对于历史基线，未来流量的总体平均值没有变化（在 0.05 水平上具有统计显着性）。此外，结果显示，预计在大部分雨季（12 月至 3 月），径流流量将增加，而在一年中的其余时间（即雨季较湿润，旱季较干燥），预计流量会减少。我们认为，加利福尼亚州水流的预计变化是由在变暖气候下雪模式和降水极端情况的预期变化驱动的。未来低流量和极高流量的变化可能对水资源规划、干旱管理、基础设施设计和风险评估产生重大影响。