紫色丘陵区降雨侵蚀力简易算法的模拟

Simulation on simple algorithm of rainfall erosivity in purple hilly area

降雨侵蚀力是评价一个地区潜在水力侵蚀危险性和严重程度的重要参数。该文基于野外人工模拟降雨的侵蚀试验,对紫色丘陵区降雨侵蚀力的简易算法进行了模拟研究。结果表明:紫色丘陵区降雨量与土壤侵蚀产流、产沙之间存在极显著正相关,各时段降雨强度I(5、10、15、30、45min)能很好地反映紫色丘陵区土壤流失量的变化特征。基于降雨动能E和时段降雨强度的复合因子∑EI5和∑EI10能够很好地反映紫色土丘陵区径流量变化特征,∑EI5可很好地反映该地区土壤流失量变化特征。降雨量P与各时段降雨强度I的复合因子PI5、PI10、PI15对紫色丘陵区坡地产流、产沙起关键作用,尤其是PI5的作用。紫色丘陵区降雨侵蚀力简易计算公式为PI5和∑EI5且二者之间存在定量转换关系,该公式提高了降雨侵蚀力在土壤侵蚀预报模型中的应用价值。对于紫色丘陵区一次降雨而言,5、10、15min降雨强度及降雨量是水土保持的关键性时段,也是水土资源利用的最佳调控时段;尤其是前5min的雨强、雨滴大小分布、降雨量对坡地水土流失起重要作用。

The rainfall erosivity factor is an important parameter to quantitatively evaluate potential water erosion risk and its serious consequence in a special area.In this article,some simple algorithm of rainfall erosivity was built up by field artificial rainfall experiment in purple hilly area.The results in purple hilly area showed that：Runoff and sediment had significantly positive correlation with rainfall.Sediment was highly influenced by such period-rainfall intensity features as 5,10,15,30 and 45 min rainfall intensity.Some compound factors as∑EI5 and∑EI10 based on rainfall kinetic energy and period-rainfall intensity could reflect the varying process of runoff in slope erosion,∑EI5 could reflect the varying process of sediment at same time.Some compound factors as PI5,PI10,PI15 based on rainfall amount and period-rainfall intensity are the important factors affecting the varying process of runoff t and sediment in slope erosion in purple hilly area,especially PI5 is the most important factor affecting soil erosion process.The models with PI5 and∑EI5 as dependent variables respectively could be chosen as simple algorithm of rainfall erosivity factor in purple hilly area,and the transformed relationship between these above models is,∑EI5=24.16（PI5）,which can greatly improves the practical application of rainfall erosivity factor in these soil erosion predicting models such as universal soil loss equation（USLE）and revised universal soil loss equation（RUSLE）.For a special rainfall event in purple hilly area, such period-rainfall intensity features as 5,10 and 15 min are critical to reduce soil erosion and to increase exploitation of soil and water resources.Some precipitation features as 5 min rainfall intensity and its rainfall amount,raindrop distribution can take more important role for water and soil loss of slope land in purple hilly area.