The frequency of extreme hydrological events highlights the need to establish an empirical model of soil organic carbon (SOC) loss based on hydraulic characteristics. This model would aid in understanding and mitigating excessive SOC loss (SOCL) on the Loess Plateau, where severe erosion occurs. To construct such a model, we established five study plots of similar slope in the Loess Plateau: four experimental vegetation successional communities and one bare land control. An in situ field scouring experiment was carried out to measure and analyze soil erosion, hydraulic parameters, and SOCL. The first scour saw the greatest increase in sediment concentration (0.007 g ml⁻¹) and sediment amount (2.886 kg) and the most significant SOC loss (8.361 g). Further scouring in each plot decreased total SOCL. The factors affecting SOCL included soil erodibility (median particle size, sediment concentration, total sediment loss, SOC concentration, total SOCL) and hydrodynamics (runoff depth, power, velocity, and shear force), which accounted for 93 and 29% of SOCL. Flow velocity, especially 2 m from the bottom of the transition section (L2), was most closely correlated to SOC concentration (0.681; P < .05). Flow velocity affects selective migration of sand in sediment, thus affecting SOC concentration. We based our sediment and SOCL model on observed hydrodynamics, including V2 (flow velocity at L2) in said model. Predicted values supported measured values more precisely (R² > .98). Our findings and developed model aid in predicting SOCL on slopes during severe erosion events.

中文翻译：

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黄土高原地区持续极端冲刷事件中的泥沙和土壤有机碳损失

极端水文事件的频率凸显了建立基于水力特征的土壤有机碳（SOC）损失经验模型的必要性。该模型将有助于理解和减轻发生严重侵蚀的黄土高原上的过度SOC损失（SOCL）。为了构建这样的模型，我们在黄土高原建立了五个相似坡度的研究地块：四个试验性植被演替群落和一个裸地控制区。进行了现场现场冲刷实验，以测量和分析土壤侵蚀，水力参数和SOCL。第一次冲刷发现沉积物浓度增加最大（0.007 g ml ^-1）和沉积物量（2.886千克）和最显着的SOC损失（8.361克）。在每个地块中进一步冲刷会降低总SOCL。影响SOCL的因素包括土壤侵蚀性（中值粒径，沉积物浓度，总沉积物损失，SOC浓度，总SOCL）和流体力学（径流深度，功率，速度和剪切力），分别占SOCL的93％和29％。流速，特别是距过渡段底部（L2）2 m处的流速与SOC浓度密切相关（0.681; P  <.05）。流速影响沙在沉积物中的选择性迁移，从而影响SOC浓度。我们基于观察到的流体动力学，包括所述模型中的V2（L2处的流速）建立了沉积物和SOCL模型。预测值更精确地支持测量值（R²  > .98）。我们的发现和开发的模型有助于预测严重侵蚀事件期间斜坡上的SOCL。