Preferential flow (PF)‐dominated soil structure is often considered a unique system consisting of micropores and macropores and thus supposed to provide dual‐pore filtering effects on hydrological signals, through which smoothing effects are likely to be stronger for matrix flow and weaker for PF via macropores. By using time series of hydrological signals (precipitation, canopy interception, throughfall, soil moisture, evapotranspiration, water storage in soil and groundwater, and catchment discharge) propagating through the Shale Hills Catchments and representative soil series, the filtering effects of the catchment and soil profiles were tested through the wavelet analysis. Typical filtering effects, that is, the characteristic of the role of soil and the groundwater table as a buffer, were observed from the wavelet spectrum, gradually smoothing off the precipitation signal. The hypothesized dual‐pore style filtering effects of the soil profile were also confirmed through the coherence spectra and phase differences, rendering them applicable for possible use as “fingerprints” of PF to infer subsurface flow features. We found that PF dominates the catchment's discharge response at the scales from 3 to 12 days, which contributes to the catchment discharge mainly as subsurface lateral flow at upper or middle soil horizons. Through subsurface PF pathways, even the hilltop is likely hydrologically connected to the valley floor, building connections with or making contributions to the catchment discharge. This study highlights the potential of wavelet analysis for retrieving and characterizing subsurface flow processes based on the revealed dual‐pore filtering effects of the soil system. Although some limitations and uncertainties still exist, we believe that wavelet methods provide a highly potential but underexplored approach to studying subsurface hydrology.

中文翻译：

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从小波分析页岩丘陵流域地下优先流特征

优先流（PF）为主的土壤结构通常被认为是由微孔和大孔组成的独特系统，因此应该对水文信号提供双孔过滤效果，通过该效果，基质流的平滑作用可能会增强，而PF的平滑作用会减弱通过大孔。利用通过页岩山流域和代表性土壤序列传播的水文信号的时间序列（降水，冠层截留，穿透，土壤水分，蒸散量，土壤和地下水中的蓄水量以及流域流量）传播，对流域和土壤的过滤效果轮廓通过小波分析进行了测试。从小波光谱中观察到典型的过滤效果，即土壤和地下水位作为缓冲物的特征，逐渐消除降水信号。还通过相干光谱和相差证实了假设的土壤剖面双孔型过滤效果，使其适用于可能用作PF的“指纹”以推断地下流动特征。我们发现，PF在3到12天的尺度上主导着集水区的流量响应，这主要是由于上层或中层土壤层的地下侧向流而导致集水区流量的增加。通过地下PF路径，即使是山顶也可能在水文上与谷底相连，与集水区的排放建立联系或为集水区做出贡献。这项研究强调了小波分析在揭示土壤系统的双孔过滤效应的基础上检索和表征地下流动过程的潜力。尽管仍然存在一些局限性和不确定性，但我们认为小波方法为研究地下水文学提供了一种很有潜力但尚未被充分研究的方法。