坡度对紫色土坡耕地侵蚀性降雨值的影响

侵蚀性降雨标准是指将发生侵蚀和不发生侵蚀的降雨区分开来的某种降雨参数的临界值.该标准值的确定可以为次降雨是否引起土壤侵蚀和土壤养分流失作出初步判断.利用遂宁水土保持实验站坡耕地小区观测资料,分析发现同一时间序列中坡度对侵蚀次数有极显著的影响(相关系数r=0.968),并拟定川中紫色土坡耕地 5°,10°,15°,20°和25°的侵蚀性降雨的雨量标准分别为55.7,42.9,39.9,39.5,32.0 mm;平均雨强标准分别为8.87,7.86,5.53,5.36,5.24 mm/h;PI标准分别为552.12,416.16,351.09,331.53,239.29 mm~2/h.并通过回归分析拟合了侵蚀性降雨雨量标准与坡度,平均雨强标准与坡度,PI标准与坡度之问的函数关系.

Influences of Slope Gradient on Erosive Rainfall Valves in Slope Cropland with Purple Soil

Erosive rainfall standard refers to the critical value of rainfall differentiating the occurrence and no n-occurrence of erosion by individual rainfall. The determination of the standard can judge whether or not individual rainfall leads to soil erosion and soil nutrient loss. Based on the observed data from slo pe cropland runoff plots,its found that slope gradient has a sig nificant impact on the number of erosion events in the same time series (correlation coefficientr=0.968) and the standard of erosive rainfall in the purple soil area of M id-Sichuan is drafted. The precipitatio n standar ds of erosive rainfall for 5,10,15,20,and 25 slopecro plands are 55.7,42.9,39.9,39.5,and 32.0 mm; the average rainfall intensity standards, 8.87,7.86,5.53,5.36,and 5.24 mm/ h;and the PI standards, 552.12,416.16,351.09, 331. 53, and 239. 29 mm²/ h,respectively. T he relationships betw een precipitation standar d and slope gradient, average rainfall intensity standard and slo pe gradient, and PI standard and slope gradient are fitted by regression analysis.