降雨-植被耦合特征是决定土壤侵蚀的关键性要素,研究降雨侵蚀力的年内变化特征对于揭示不同区域降雨-植被的耦合特征、判定土壤侵蚀的危险期具有重要意义。该文利用中国西南山区439个气象站、水文站的逐日降雨量资料,估算了每个台站逐月降雨侵蚀力,并应用重心模型分析了西南山区降雨侵蚀力的年内变化特征。研究结果表明:西南山区春、夏、秋、季四季降雨侵蚀力变化明显,夏季最高,冬季最低。各季节的降雨侵蚀力空间分布与降水量相似,都表现出东南向西北逐渐递减的趋势。降雨侵蚀力年内分配曲线主要有"单峰型"和"双峰型"2种,绝大多数地区降雨侵蚀力年内分配曲线是"单峰型",峰值出现在6月、7月或8月份,青藏高原区域降雨侵蚀力年内分配曲线是"双峰型",有6月和9月2个峰值。从东南部向西北部,降雨侵蚀力峰值出现的月份不断推后。西南山区降雨侵蚀力重心年内先向北迁移,然后向南迁移,形成一个循环,这展示了季风气候影响下的西南山区降雨侵蚀力年内变化特征。

The correlation between rainfall time-series and vegetation time-series is one of the key factor that determining the soil erosion. So, study on the annual variation of rainfall erosivity has very important significance for revealing the characteristics of the correlation between rainfall time-series and vegetation time-series and determining the dangerous period of the soil erosion. 439 meteorological stations and hydrological stations were used in this study to estimate the rainfall erosivity in the southwest China. The annual variation of rainfall erosivity was discussed based on the gravity center model. The results showed that the rainfall erosivity changed significantly in a year, which was the highest in summer and was the lowest in winter. The spatial distribution of rainfall erosivity has the decreasing trend from the southeast to the northwest regions of the southwest China. The spatial distribution of rainfall erosivity is similar to that of precipitation. The annual variation of the monthly mean rainfall erosivity in southwest China can be divided into two patterns. One is single peak pattern for the most areas, with peak values occurring in June, July or August. The other one is two peaks pattern for the east part of Qinghai-Tibet Plateau, with peak values occurring in June and September respectively. The peak values are postponed form the southeast of the study area to the northwest of the study area. The gravity center of the rainfall erosivity in the southwest China moves northward firstly, and then moves southward during a year. This shows the annual variations of rainfall erosivity during the year under the influence of monsoon climate in the southwest China.