侵蚀性降雨标准研究

Study on Standard of Erosive Rainfall

建立侵蚀性降雨标准 ,是为了区分发生和不发生侵蚀的降雨事件 ,从而大大减少计算降雨侵蚀力的工作量 ,并提高土壤侵蚀预报精度。利用陕西团山沟小流域及所在 3个小区 1961- 1969年的降雨过程资料 ,以漏选和多选降雨事件的降雨侵蚀力相等为原则 ,分别建立了黄土高原坡面侵蚀的侵蚀性降雨雨量标准 12 mm,平均雨强标准 0 .0 4 mm/min,最大 30 min雨强标准 0 .2 5mm/min。其中时段雨强标准筛选精度最高 ,可剔除 88%以上的降雨事件 ,只有5.3%的错选度。其次是平均雨强标准 ,雨量标准筛选精度最差。漏选降雨侵蚀力之和与多选降雨侵蚀力之和相抵为原则建立的侵蚀性降雨标准 ,对于计算降雨侵蚀力 ,提高土壤侵蚀预报精度 ,具有重要意义。

To pick out the erosive rainfalls from all the rainfall events is the aim of studying erosive rainfall standard, which can decrease the work of calculating rainfall index largely and improve the accuracy in predicting soil erosion. Using the rainfall data from 3 plots and one small watershed in Tuanshangou of Shannxi Province, this study gave the erosive rainfall standards on Loess Plateau, which included the standards of rainfall, average rainfall intensity and break point intensity.Based on the principle that the erosivity of un accounted erosive rainfall is equal to that of accounted un erosive rainfall, the rainfall standard was 12mm, average rainfall intensity standard was 0.04mm/min, and standards of break point of 5, 10, 30, and 60 minutes were 0.50,0.40,0.25,and 0.15mm/min. The most accurate standard is the break point intensity, which deleted 88% more rainfall events and had only 5.3% relative error. The next is the standard of average rainfall intensity, and the rainfall standard is the worst one in picking out erosive rainfalls. Of three standards, rainfall, average intensity, and break point intensity, users can decide which one should be used according to the data available and picking accuracy. This result is significant in applying for calculating rainfall erosivity and predicting soil erosion.