玉溪市尖山河小流域侵蚀性降雨的特征

Characteristics of Erosive Rainfall in Jianshan River Watershed of Yuxi City

[目的]分析侵蚀性降雨特征及其与产沙之间的关系,为水土保持生态建设提供参考依据。[方法]基于尖山河小流域降雨资料和径流小区监测资料,选取2014—2016年的降雨历时、降雨量、平均雨强、最大30min雨强和最大60min雨强5个指标,分析不同降雨量级别和不同降雨强度等级下的降雨场次、侵蚀性降雨量、侵蚀性降雨频率、各侵蚀性降雨特征指标与产沙的相关性。[结果](1)从3a的降雨情况来看,大体变化类似正态分布。研究区的降雨主要集中于5—10月,汛期在9月;从10月开始,降雨量逐渐减少,而从季节分布来看,降雨集中在夏秋两季,干湿季节明显。这一规律与大陆性季风气候特点有关。(2)玉米地和烤烟地径流小区的平均产沙模数均显著高于次生林、人工林地和灌草地径流小区。(3)在一定降雨强度范围内(0~5mm/h),次生林径流小区的产沙量与降雨量和最大60min雨强呈显著正相关关系,烤烟地径流小区的产沙量与降雨量呈显著相关关系。[结论](1)降雨特征与大陆性季风气候相吻合,集中在夏秋两季,呈正态分布;(2)覆盖度不同的土地利用方式在拦截泥沙和径流等方面存在很大差异,耕作方式和农作物对土壤流失也有不同程度的影响。

[Objective] To analyze the characteristics of erosive rainfall and its relationship with sediment production in order provide a basis for soil and water conservation and ecological improvement.[Methods] Based on rainfall data of Jianshan river watershed and monitoring data of runoff plot from 2014 to 2016, we selected rainfall duration, rainfall, average rainfall intensity, the maximum rainfall intensity within 30 minutes and 60 minutes to analyze rainfall events, the amount and frequency of erosive rainfall under different level of rainfall and rainfall intensity, and then we analyzed the relationships between sediment yield and various erosive rainfall indexes.[Results] ① Threes years data showed that monthly change of rainfall generally conformed to Gaussian distribution and the rainfall in research area was mainly concentrated in May, June, Junly, August, September and October. The flooding season was in September. After October, the rainfall gradually decreased. In terms of the seasonal distribution, the rainfall was mainly concentrated in summer and autumn, and wet and dry season was clear. This pattern relates to continental monsoon climate. ② The mean sediment yield of corn field and tobacco field runoff plot was significantly higher than that in secondary forest, artificial forest and shrub-grass land runoff plot. ③ Within a certain range of rainfall intensity （0~5 mm/h）, the sediment yield and rainfall of secondary forest runoff plots showed a significantly positive correlation with rainfall and I60, and sediment yield of tobacco field runoff plots had a significantly correlation with rainfall.[Conclusion] ① The characteristics of rainfall is coincident with continental monsoon climate, with rainfall concentrated in summer and autumn and Gaussion distribution; ② The land use with different coverage produced big differences in interceping sediment and runoff. Tillage methods and crop species also have different effects on soil loss.