利用Euro-CORDEX多模式集合预估伊比利亚半岛北部的水文变化
Projected hydrologic changes over the north of the Iberian Peninsula using a Euro-CORDEX multi-model ensemble
AI总结：
本研究基于18个Euro-CORDEX模式集合驱动VIC模型，预估杜罗河源头区未来水文变化，揭示径流显著减少、融雪贡献下降及季节性特征改变。
摘要：
本研究探讨气候变化对杜罗河流域源头区水文的影响，该流域是伊比利亚半岛最大的流域。为此，收集了18个Euro-CORDEX模式实验在1975-2005年和2021-2100年、RCP4.5和RCP8.5情景下的集合结果，并将其作为水文模拟过程中可变下渗容量模型（VIC）的气象强迫。利用若干评估指标，在未来时段预估的水文变化在年和季节尺度上进行了分析，这些指标包括大气和陆面变量的增量变化、总体水量平衡中的径流比和蒸散发比、融雪对总径流的贡献，以及平均水文年日流量过程线的质心位置。在RCP8.5情景下，2071-2100年流域多个区域的年径流减少幅度高达40%，其原因是南部子流域降水减少，以及北部降水减少与蒸散发增加的共同作用。径流比和蒸散发比表明，流域北部有向蒸发型状态转变的趋势，而南部的蒸发响应则有所增强。季节性径流变化大多为负值，且取决于所考虑的季度，春季和夏季的减少更为显著，秋季和冬季的减少程度较轻。融雪对总径流的贡献大幅下降，秋季和春季的降幅达到-80%，这表明杜罗山脉的积雪状态发生了变化。最后，质心位置的年和季节变化反映了流量过程线的形状变化，构成了一种季节性度量，并与径流增量变化表现出较高的相关程度。
英文摘要：
This study explores the impacts of climate change on the hydrology of the headwater areas of the Duero River Basin, the largest basin of the Iberian Peninsula. To this end, an ensemble of 18 Euro-CORDEX model experiments was gathered for 1975-2005 and 2021-2100, under the RCP4.5 and RCP8.5, and were used as the meteorological forcings of the Variable Infiltration Capacity (VIC) during the hydrological modelling exercise. The projected hydrologic changes for the future period were analyzed at annual and seasonal scales using several evaluation metrics, such as the delta changes of the atmospheric and land variables, the runoff and evapotranspiration ratios of the overall water balance, the snowmelt contribution to the total streamflow and the centroid position for the daily hydrograph of the average hydrologic year. Annual streamflow reductions of up to 40% were attained in various parts of the basin for 2071-2100 under RCP8.5 scenario, and resulted from the precipitation decreases in the southern subwatersheds and the combined effect of the precipitation decreases and evapotranspiration increases in the north. The runoff and the evapotranspiration ratios evinced a tendency towards an evaporative regime in the north part of the basin and a strengthening of the evaporative response in the south. Seasonal streamflow changes were mostly negative and dependent on the season considered, with greater detriments in spring and summer, and less intense ones in autumn and winter. The snowmelt contribution to the total streamflow was strongly diminished with decreases reaching -80% in autumn and spring, thus pointing to a change in the snow regime for the Duero mountains. Finally, the annual and seasonal changes of the centroid position accounted for the shape changes of the hydrograph, constituting a measure of seasonality and reflecting high correlations degrees with the streamflow delta changes.
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