Department of Civil and Environmental Engineering and Earth Sciences, College of Engineering, University of Notre Dame, Notre Dame, IN 46556, United States of America.
Department of Civil and Environmental Engineering and Earth Sciences, College of Engineering, University of Notre Dame, Notre Dame, IN 46556, United States of America.
Sci Total Environ. 2019 Feb 10;650(Pt 1):1261-1277. doi: 10.1016/j.scitotenv.2018.09.063. Epub 2018 Sep 7.
Analyzing future changes in hydrologic extremes such as floods, low flows, and soil moisture extremes is important because many impacts on ecosystems and human systems occur during extreme events. To quantify changes in hydrologic extremes, this study conducts hydrologic modeling experiments over 20 Midwestern watersheds using the Variable Infiltration Capacity (VIC) model forced by historical observed datasets and future projections from statistically downscaled Global Climate Model (GCMs) simulations. Our results show that peak daily streamflow at the 100-yr reoccurrence interval will increase (+10-30%) in most watersheds by 2080s due to significant increases in precipitation (P) and increasing P as rainfall during winter and spring seasons. The simulations also show strong shifts towards earlier peak flow timing (up to a month), especially in strongly snowmelt-dominated watersheds. These effects are linked to strong decreasing trends in maximum Snow Water Equivalent (SWE) with warming, which are simulated over essentially the entire domain. Projected changes in 7-day extreme low flows are smaller in magnitude (-10-+10%) with somewhat larger decreases simulated at the end of century; however, the timing of extreme low flows is projected to shift from winter/spring to summer and fall in strongly snowmelt-dominated watersheds in the northernmost parts of the domain. Extreme low soil moisture increases over most of the domain in the future projections up to the 2050s, but by the 2080s there are more widespread decreases in extreme low soil moisture, especially in the northernmost parts of the domain.
分析水文极值(如洪水、低流量和土壤湿度极值)的未来变化很重要,因为许多对生态系统和人类系统的影响都发生在极端事件中。为了量化水文极值的变化,本研究使用可变入渗容量(VIC)模型在 20 个中西部流域上进行水文建模实验,该模型由历史观测数据集和从统计降尺度全球气候模型(GCM)模拟中得到的未来预测数据驱动。我们的研究结果表明,由于降水(P)显著增加以及冬季和春季降雨期间 P 增加,在 2080 年代,大多数流域的 100 年重现期峰值日流量将增加(10-30%)。模拟还显示出峰值流量时间向早期的强烈转变(最多提前一个月),尤其是在强烈的融雪主导流域。这些影响与变暖导致的最大雪水当量(SWE)的强烈下降趋势有关,这些趋势模拟几乎涵盖了整个研究区域。7 天极端低流量的预计变化幅度较小(-10-+10%),在本世纪末模拟的降幅较大;然而,在研究区域最北部的强烈融雪主导流域中,极端低流量的时间预计将从冬季/春季转移到夏季和秋季。在未来的预测中,大多数地区的极端低土壤湿度将增加,直到 2050 年代,但到 2080 年代,极端低土壤湿度的减少将更加广泛,尤其是在研究区域的最北部。