模拟降雨条件下坡面水流流速与径流输出特征研究

Study on the Relationship Between Flow Velocity of Sloping Face and Runoff Characteristic Under the Simulated Rainfall

利用室内人工模拟降雨试验，研究不同坡度径流小区的水流流速与径流输出特征间的关系。研究结果表明：定坡长土槽坡度变化为5～20°时，水流流速随着坡面坡度的增加呈递增趋势；同时，同一坡度下坡面水流流速随时间的变化大体上是增加的过程；在模拟降雨条件下，30min内坡面水流速度的变化趋势分为3个阶段：降雨径流产生初期，坡面微形态的形成阶段和侵蚀沟形成阶段。在25°坡面上，这3个阶段的界限不明显。另外，得出了径流量输出特征与水流速度有着密切的幂函数相关关系，且5°，10°，15°，20°坡面流速与径流量的相关系数在0．9左右，但25°坡面的相关系数较小。根据方差得出，5～25。坡面流速与径流量关系显著，坡度越大，流速对径流量的影响越显著，并分析出2u～25°是坡地土壤侵蚀的临界坡度。

The relationship between flow velocity of sloping face and runoff characteristic was studied under the simulated rainfall in this paper. The results indicated that： when the slope of the fixed long plot ranged from 5°to 20°, the flow velocity was increased along with the slope. Meanwhile, the flow velocity was increased with time at the same slope. The trend of flow velocity can be divided into three phases： the initial stage of runoff from precipitation; the stage of minute form on the slope face; the stage of rills came basically into shape. While the slope gradient was 25°, the demarcation of three stages was unclear. The close relationship between flow velocity of sloping face and runoff characteristic can be illustrated by power function y=ax^b （0 〈b〈21）. and the correlation coefficient was around 0.9 when the slope ranges from 5°to 20°. According to the square, the relationship between flow velocity of sloping face and runoff is notable. The slope is bigger, and the velocity of flow was notable, and 20-25° is critical slope of hillside field＇s soil erosion.