雨型对华北土石山区坡面土壤侵蚀的影响

Effects of Rainfall Patterns on Slope Soil Erosion in the Rocky Mountain Area of North China

为研究雨型对华北土石山区坡面土壤侵蚀的影响,通过室内人工模拟降雨试验,以华北土石山区主要土壤类型黄土性褐土和石灰性褐土为研究对象,设计次降雨中平均降雨强度和降雨量相同的3种不同降雨类型(均匀型、增加型、减弱型对应的降雨强度组合分别为60,30~60~90,90~60~30 mm/h),分析不同雨型下华北土石山区坡面产流产沙的变化规律。结果表明:(1)不同雨型的产流时间与起始阶段降雨强度呈负相关,增加型降雨的坡面产流时间最长,且分别为均匀型和减弱型的1.98,4.15倍;减弱型降雨的总径流量和总侵蚀量最大,而均匀型降雨的最小,减弱型降雨的总径流量是均匀型和增加型降雨的1.05~1.12倍,总侵蚀量分别是增加型和均匀型的1.22,1.78倍。(2)在不同雨型下,同一降雨强度出现在不同降雨阶段,使得坡面产流产沙的过程不同。(3)同一降雨强度出现在雨型起始阶段的径流量和贡献率与结束阶段相比偏小。次降雨起始阶段的强度为30 mm/h时,黄土性褐土的侵蚀量和贡献率大于其在结束阶段的侵蚀量和贡献率,而石灰性褐土与之相反。

In order to research the impact of rainfall patterns on slope erosion in the rocky mountain area of North China,the loess cinnamon and the calcic cinnamon from this area were selected and indoor experiments were conducted.The experiment treatment included three patterns of simulated rainfalls with the same total rainfall and mean intensity,covering uniform type(60 mm/h),rising type(30~60~90 mm/h),and falling type(90~60~30 mm/h).The results indicated that:(1)The initial runoff generation time of different rainfall and patterns was negatively correlated with the rainfall intensity at the initial stage.The initial runoff generation time of the rising type slope was 1.98 and 4.15 times higher than that of the uniform and falling types,respectively.The order of total runoff and total erosion generated by different rainfall patterns was falling type>rising type>uniform type.The total runoff of the falling type was 1.05~1.12 times of other rainfall patterns,and the total erosion was 1.22 and 1.78 times of the rising and uniform types,respectively.(2)Under different rainfall patterns,the same rainfall intensity appeared in different rainfall stages,which made the processes of runoff and sediment production on the slope different.(3)The runoff and contribution rate of the same rainfall intensity at the initial stage of the rainfall pattern was smaller than that at the end stage.When the 30 mm/h rainfall intensity appeared at the beginning of the rainfall pattern,the erosion amount and contribution rate of the loess cinnamon was greater than that at the end stage,while the calcic cinnamon was the opposite.