Abstract Sandified soil slope in the semiarid ecosystems can affect overland flow velocity to accelerate soil erosion and increase sandification. For a better understanding of flow hydraulics in wind-water erosion zone of Loess Plateau, a computation method was suggested to estimate rill flow velocities over sand incorporation slope surface of sand-loess soil mixture. The sandified slopes involved three sand incorporation rates of 10%, 20%, 50%, as light, medium and severe levels of sandification, under four inflow discharges (1, 2, 4, and 8 L min−1) and four slope gradients (5°, 10°, 15°, and 25°). The measured electrolyte signals over sand incorporation surfaces were found to be initially smooth in the rising limbs. After the electrolyte solution arrived at the measurement location, part of the solute infiltrated into the surface sand layer. The electrolyte solute was absorbed by the sand layer before being slowly released into the water flow. This part should be deleted before overland flow velocity estimation. Compared with published data over loess slopes, velocities over sand incorporation surface were increased by an average of 69%, 54%, 30% for sand incorporation rates of 10, 20 and 50% respectively. Incorporation of sand particles into soil could have protected soil surface from being eroded to form rougher rill morphology, to increased flow velocity. But higher sand content also could have increased the surface frictional resistance to reduce the increase rate of overland flow velocity. For aeolian-sand incorporated loess slope, both linear regression and stepwise regression implied a positive dependency of velocities on flow rates and slope gradients, but a negative dependency on sand incorporation rates. The results will improve the understanding of overland flow hydraulics on sandified slopes.

中文翻译：

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从测得的溶质运移过程估算带偏差的砂化斜坡上地表流速的方法

摘要 半干旱生态系统中沙化土壤坡度会影响地表水流速度，加速土壤侵蚀，加剧沙化。为了更好地了解黄土高原风水侵蚀带的水流水力学，提出了一种计算方法来估算沙土混合体混砂坡面的细沟流速。砂化斜坡在四个流入流量（1、2、4和8 L min-1）和四个坡度梯度下涉及三个掺砂率，分别为10%、20%、50%，为轻度、中度和重度砂化（5°、10°、15° 和 25°）。发现在沙子掺入表面上测得的电解质信号在上升分支中最初是平滑的。电解液到达测量位置后，部分溶质渗入表层砂层。电解质溶质被砂层吸收，然后慢慢释放到水流中。这部分在地表流速估算前应删除。与已发表的黄土斜坡数据相比，掺砂率分别为 10%、20% 和 50% 时，掺砂面的速度平均提高了 69%、54%、30%。将沙粒掺入土壤可以保护土壤表面免受侵蚀，形成更粗糙的细沟形态，增加流速。但较高的含砂量也可能会增加地表摩擦阻力，从而降低地表流速的增加率。对于风沙混入的黄土坡度，线性回归和逐步回归均表明速度与流速和坡度梯度呈正相关，但对沙子掺入率的负依赖性。研究结果将增进对砂化斜坡上地表流水力学的理解。