Montanari Alberto, Nguyen Hung, Rubinetti Sara, Ceola Serena, Galelli Stefano, Rubino Angelo, Zanchettin Davide
Department of Civil, Chemical, Environmental and Materials Engineering (DICAM), Alma Mater Studiorum Università di Bologna, Bologna, Italy.
Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, USA.
Sci Adv. 2023 Aug 9;9(32):eadg8304. doi: 10.1126/sciadv.adg8304.
The causes of recent hydrological droughts and their future evolution under a changing climate are still poorly understood. Banking on a 216-year river flow time series at the Po River outlet, we show that the 2022 hydrological drought is the worst event (30% lower than the second worst, with a six-century return period), part of an increasing trend in severe drought occurrence. The decline in summer river flows (-4.14 cubic meters per second per year), which is more relevant than the precipitation decline, is attributed to a combination of changes in the precipitation regime, resulting in a decline of snow fraction (-0.6% per year) and snowmelt (-0.18 millimeters per day per year), and to increasing evaporation rate (+0.013 cubic kilometers per year) and irrigated areas (100% increment from 1900). Our study presents a compelling case where the hydrological impact of climate change is exacerbated by local changes in hydrologic seasonality and water use.
近期水文干旱的成因及其在气候变化下的未来演变仍知之甚少。基于波河河口216年的河流水量时间序列，我们发现2022年的水文干旱是最严重的事件（比第二严重的事件低30%，重现期为六个世纪），是严重干旱发生呈上升趋势的一部分。夏季河流水量下降（每年-4.14立方米/秒）比降水量下降更为显著，这归因于降水模式变化的综合影响，导致积雪比例下降（每年-0.6%）和融雪量下降（每年-0.18毫米/天），以及蒸发率增加（每年+0.013立方千米）和灌溉面积增加（自1900年以来增加了100%）。我们的研究提供了一个令人信服的案例，即气候变化的水文影响因水文季节性和用水的局部变化而加剧。
