In temperate regions, snow and its meltwater constitute primary freshwater resources and snowmelt isotopes offer valuable insights into understanding the snowmelt processes including the timing and contribution of snowmelt to the soil and watershed in spring. Assessing the storage and movement of liquid water within natural snowpacks, a previously unquantified aspect, holds significance for predicting natural hazards and managing water resources for agricultural purposes and ecosystem health. The escalating occurrence of rain-on-snow (ROS) events, attributed to winter warming, has the potential to trigger natural hazards and surface runoff into major river systems in temperate climate regions. End member mixing calculations (EMMC) based on isotopic and chemical tracers were employed to quantify the proportions of rainwater, meltwater, and pore water within the snowpack discharge. In this study, artificial rain-on-snow experiments involving conservative anions and stable water isotopes were conducted at the surface of snowpack to differentiate each component (rainwater, pore water, and snowmelt) within the discharge collected at the bottom of the snowpack. Pore water content exhibited a shift from 1.1 ± 1.1% (± 1σ, N = 23) after the initial artificial ROS event to 2.8 ± 1.2% (± 1σ, N = 19) following the spray in our experiment. Based on the EMMC, the contributions of rainfall, pore water, and snowmelt to the meltwater discharge were 2,620.2 L (63.3%), 829.0 L (20.0%), and 687.4 L (16.6%), respectively. Notably, contrary to prior studies, our experimental results suggest that rainwater reached the bottom through multiple rapid flow channels before matrix flow occurred. This experimental approach provides additional insights into the dynamics of water percolation in snowpacks during rain-on-snow events.

在温带地区，雪及其融水构成了主要的淡水资源，融雪同位素为了解融雪过程提供了宝贵的见解，包括春季融雪的时间和对土壤和流域的贡献。评估天然积雪中液态水的储存和移动是一个以前未量化的方面，对于预测自然灾害和为农业目的和生态系统健康管理水资源具有重要意义。由于冬季变暖，雨雪 （ROS） 事件的发生率不断升级，有可能引发自然灾害和地表径流进入温带气候地区的主要河流系统。采用基于同位素和化学示踪剂的端元混合计算 （EMMC） 来量化积雪排放中雨水、融水和孔隙水的比例。在这项研究中，在积雪表面进行了涉及保守阴离子和稳定水同位素的人工雨雪实验，以区分积雪底部收集的排放物中的每个成分（雨水、孔隙水和融雪）。在我们的实验中，孔隙含水量从初始人工 ROS 事件后的 1.1 ± 1.1% （± 1σ， N = 23） 转变为喷洒后的 2.8 ± 1.2% （± 1σ， N = 19）。根据 EMMC，降雨、孔隙水和融雪对融水排放的贡献分别为 2,620.2 L （63.3%） 、 829.0 L （20.0%） 和 687.4 L （16.6%）。值得注意的是，与之前的研究相反，我们的实验结果表明，雨水在基质流发生之前通过多个快速流道到达底部。 这种实验方法为雨雪事件期间积雪中水渗透的动力学提供了额外的见解。