不同降雨强度对紫色土坡面侵蚀过程的影响

为研究不同雨强对紫色土坡面侵蚀过程的影响,通过人工模拟降雨试验和室内分析,采用降雨总量(30mm)一定、降雨历时不定的原则,在2种覆盖度(50%和75%)下,分析了3个雨强(0.5,1.0,1.5mm/min)对紫色土土壤坡面产流产沙的影响。结果表明:在50%和75%覆盖度下,(1)雨强越大紫色土坡面产流总量和径流率越大。相同时间内,不同雨强(0.5,1.0,1.5mm/min)下的2种覆盖度产流量分别占坡面产流总量的18%,30%,52%。(2)雨强越大紫色土坡面产沙量和侵蚀率越大。相同时间内,不同雨强(0.5,1.0,1.5mm/min)下,2种覆盖度产沙量分别占坡面产沙总量的13%,33%,54%。(3)紫色土坡面侵蚀泥沙中的水稳性团聚体的粒径主要集中在0.25,3mm,分别占泥沙总量的74%和67%,0.25~3mm粒径的水稳性团聚体分别占泥沙总量的30%和26%。(4)相关分析表明,雨强和紫色土坡面产流产沙量均为极显著正相关(P0.01)。雨强与产沙量之间均拟合为一次线性方程;雨强与产流量之间分别拟合为一次线性方程和二次方程。研究结果为控制紫色土坡面水土流失和揭示其相关侵蚀机理提供参考。

Effects of Different Rainfall Intensity on the Slope Erosion Process in Purple Soil

In order to study the influence of different rainfall intensity on the erosion, artificial rainfall simulation experiment and indoor analysis were connducted to analyze the effects of three rainfall intensity (0.5,1.0,1.5 mm/min) on runoff and sediment yield in purple soil. The results showed as follows. Under 50% and 75% vegetation coverage, (1) The greater the rainfall indestiny, the more the runoff production rate and the runoff volume in the purple soil. In the same time, under the three kinds of rainfall intensity, the surface runoff accounted for 18%, 30%, and 52% of the total runoff volume, respectively. (2)The greater the rainfall intensity, the more the sediment yield and erosion rate occured. In the same time, under three kinds of rainfall intensity the sediment yield in purple soil accounted for 13%,33%, and 54% of the total sediment yield, respectively. (3) The particle size of water-stable aggregate in erosion sediment was mainly concentrated in < 0.25 and > 3 mm. The total amount of the two particle size accounted for 74% and 67% of the total sediment, respectively, while water-stable aggregate particle size of 0.25~3 mm accounted for 30% and 26%, respectively. (4) There was a significant positive correlation between rainfall intensity and the yield of runoff and sediment in the purple soil (P < 0.01). The linear equation was synthesized by rainfall intensity and sediment yield. The correlation coefficients were 0.96 and 0.97, respectively. A linear equation and a quadratic equation were synthesized by rainfall intensity and runoff yield, respectivelly, and the correlation coefficients were 0.89 and 0.94, respectively. The results can provide references for controlling soil erosion in purple soil and revealing related erosion mechanism.