雨型对东北黑土区坡耕地土壤侵蚀影响的试验研究

Effects of rainfall patterns on hillslope farmland erosion in black soil region of Northeast China

降雨雨型对土壤侵蚀过程有重要的影响，也是当前土壤侵蚀研究的热点之一。通过野外原位人工模拟降雨试验，设计了次降雨中平均降雨强度、总降雨量相同的4种不同降雨雨型（均匀型：降雨强度为60mm／h；峰值型：降雨强度分布为30-90-60mm／h；延迟型：降雨强度分布为60-30-90mm／h；减弱型：降雨强度分布为90-60-30mm／h），研究降雨雨型变化对东北黑土区坡耕地土壤侵蚀的影响。结果表明：各雨型条件下休闲坡耕地径流总量的大小顺序为延迟型〉减弱性〉均匀型〉峰值型，而土壤侵蚀总量的大小顺序为减弱型〉均匀型〉延迟型〉峰值型。延迟型雨型的坡面径流总量是其它雨型的1．02-1．45倍，减弱型降雨的侵蚀总量分别是均匀型、延迟型和峰值型的1．03、1．36和2．68倍。同一雨强在不同降雨雨型中出现的位置不同，其产生的坡面径流量和侵蚀量对坡面总径流量、总侵蚀量的贡献率也不同，分布在降雨雨型起始位置的雨强对坡面径流量的贡献率最小；除30mm／h降雨强度外，分布在降雨雨型起始位置的雨强对坡面侵蚀的贡献率最大。研究还发现，试验设计中减弱型降雨雨型与东北黑土区夏季主要侵蚀雨型特点类似，是造成东北黑土区坡耕地土壤侵蚀相对严重的主要雨型。

Rainfall pattern as an important parameter has a significant influence on soil erosion process. To investigate the effects of rainfall pattern on hillslope farmland erosion in black soil region, field experiments were conducted. The experiment treatment included four patterns of simulated rainfalls with the same total rainfall, covering Uniform-type （60mm/h）, Peak-type （30-90-60mm/h）, Delay-type （60-30-90mm/h） and Reduced-type （90-60-30mm/h）. The results show that the total runoff of each rainfall pattern for fallow land decreased in the order of Delay-type 〉 Reduced-type 〉 Uniform-type 〉 Peak-type, and the total runoff of the Peak-type treatment is 1.02-1.45 times higher than the others. The total soil loss decreased in the order of Reduced-type 〉 Uniform-type 〉 Delay-type 〉 Peak-type, and the Reduced-type treatment produced the highest soil loss which was 1.03-2.68 times higher than the other rainfall patterns. The position of rainfall intensity in each rainfall pattern did have important effects on the contribution rates of runoff to the total runoff and soil erosion to the total soil loss. The contribution rate of runoff in the rainfall intensity which appeared at the initial stage of a rainfall pattern was lower than that in the same rainfall intensity which appeared at the middle stage or the last stage. However, for the heavier rainfall intensity, its soil loss contribution rate was the highest when it appeared at the initial stage of a rainfall pattern compared with other positions. This study found the Reduced-type was similar to the major erosive rainfall pattern in black soil region which resulted in relatively severe soil erosion on hillslope farmland.