Altered rainfall patterns reshape hillslope water balance and amplify carbon and nitrogen losses in a periglacial grassland

IF 6.3 1区地球科学 Q1 ENGINEERING, CIVIL

Journal of Hydrology Pub Date : 2025-10-16 DOI:10.1016/j.jhydrol.2025.134421

Wencong Lv , Jianqing Du , Liyuan Ma , Fei Wang , Lizhen Cui , Haijun Zhang , Danni Zhou , Qiang Liu , Haishan Niu , Yanbin Hao , Xiaoyong Cui , Yanfen Wang

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引用次数: 0

Abstract

Global warming is shifting rainfall patterns towards fewer but more intense events, leading to longer intervals between rainfall events. However, the effects of these changes on hydrological processes and elemental transport in the highly vulnerable periglacial ecosystems remain largely unexplored. This study used a rainfall manipulation experiment to examine how altering rainfall intervals with fixed seasonal total precipitation affects hydrological processes and carbon, nitrogen, and phosphorus export in a periglacial grassland on the Tibetan Plateau. Four treatments were applied on a uniform slope (∼11°): natural rainfall (CK), 3-day interval (P1), 7-day interval (P2), and 11-day interval (P3). Our results revealed that altered rainfall patterns reshape hillslope water balance. Specifically, P1 increased surface runoff (SR), soil water storage (SWS) and soil evaporation while reducing deep percolation (DP), because frequent small rainfall events enhanced soil water retention in the 0-30 cm layer while limiting infiltration into deeper layers. In contrast, P2 and P3 significantly increased SR while reducing SWS, resulting in a non-significant effect on DP. Moreover, distinct thresholds were identified for the generation of SR and DP at 1.8 mm and 1 mm rainfall, respectively. Additionally, altered rainfall patterns significantly increased the losses of dissolved carbon, total nitrogen and nitrate in SR but did not affect ammonium and phosphate. Notably, nitrate losses exhibited a nonlinear response to changing rainfall patterns, which peaked at a 7-day interval instead of 11-day interval with the highest single rainfall amount. This suggests that the extreme rainfall events may not affect the dissolved nitrogen exports in the periglacial grasslands as it requires not only a large single rainfall amount but also high rainfall frequency. Therefore, future studies should consider the interactions between rainfall frequency and single event size to disentangle the responses of hydrological and biogeochemical processes to climate extremes in these fragile periglacial ecosystems, thus supporting sustainable watershed management for the Asian Water Tower.

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降雨模式的改变重塑了坡面水平衡，加大了冰缘草原的碳氮损失

全球变暖正在改变降雨模式，使降雨事件更少，但强度更大，导致降雨事件之间的间隔更长。然而，在高度脆弱的冰缘生态系统中，这些变化对水文过程和元素运输的影响在很大程度上仍未被探索。在均匀坡度（~ 11°）上施用四种处理：自然降雨（CK）、间隔3天（P1）、间隔7天（P2）和间隔11天（P3）。我们的研究结果表明，降雨模式的改变重塑了山坡的水平衡。具体而言，P1增加了地表径流（SR）、土壤储水（SWS）和土壤蒸发，同时减少了深层渗流（DP），因为频繁的小降雨事件增强了0-30 cm层的土壤保水，同时限制了向更深层的入渗。相比之下，P2和P3显著提高了SR，同时降低了SWS，对DP的影响不显著。此外，在降雨量为1.8 mm和1 mm时，SR和DP的产生分别有不同的阈值。此外，降雨模式的改变显著增加了SR中溶解碳、总氮和硝酸盐的损失，但对铵和磷酸盐的损失没有影响。硝态氮损失对降雨模式的变化表现出非线性响应，单次降雨量最高时，硝态氮损失的峰值出现在7 d，而不是11 d。这表明极端降雨事件可能不会影响冰缘草原的溶解氮输出，因为它不仅需要大的单次降雨量，而且需要高的降雨频率。因此，未来的研究应考虑降雨频率和单次事件大小之间的相互作用，以解开这些脆弱的冰缘生态系统中水文和生物地球化学过程对极端气候的响应，从而支持亚洲水塔的可持续流域管理。

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来源期刊

Journal of Hydrology 地学-地球科学综合

CiteScore

11.00

自引率

12.50%

发文量

1309

审稿时长

7.5 months

期刊介绍： The Journal of Hydrology publishes original research papers and comprehensive reviews in all the subfields of the hydrological sciences including water based management and policy issues that impact on economics and society. These comprise, but are not limited to the physical, chemical, biogeochemical, stochastic and systems aspects of surface and groundwater hydrology, hydrometeorology and hydrogeology. Relevant topics incorporating the insights and methodologies of disciplines such as climatology, water resource systems, hydraulics, agrohydrology, geomorphology, soil science, instrumentation and remote sensing, civil and environmental engineering are included. Social science perspectives on hydrological problems such as resource and ecological economics, environmental sociology, psychology and behavioural science, management and policy analysis are also invited. Multi-and interdisciplinary analyses of hydrological problems are within scope. The science published in the Journal of Hydrology is relevant to catchment scales rather than exclusively to a local scale or site.