中文摘要：

系统收集和整理、分析了汶川地震灾区2008-2011年的160次泥石流事件和其对应的降雨过程,发现不同降雨因子对泥石流的发生所起的作用有所差异,超过77%的泥石流都是由暴雨激发,说明直接降雨因子,如当次降雨量和峰值雨强是诱发泥石流的最关键因子。通过各种降雨阈值方法的结果比较,发现不同区域各种降雨参数对泥石流发生的影响程度不同,因此用于泥石流预报的降雨指标不同,应采用的预报模型和临界阈值也不同。对于崇州市,可选用峰值雨强作为预报指标;汶川县可选用当次降雨量作为预报指标,对于其他地区,适宜用多因子模型（I-R和I-D）进行预报;相比较而言,绵竹、都江堰等地区的泥石流受前期降雨的作用影响较为明显,因此最适宜用峰值降雨强度和有效前期降雨关系（I-RT模型）进行预报。个别地区的阈值年度变化显示地震灾区泥石流的降雨阈值呈回升趋势,但远远未恢复至地震之前的水平。研究可为地震灾区的泥石流预警预报研究做出贡献。

英文摘要：

Identification of rainfall thresholds is crucial for debris flow forecasting and hazards mitigation. This study collected 160 post earthquake debris flow events and responding rainfall processes through field investigation,and literature research,etc. By analyzing of the effect of different rainfall indexes for debris flow formation,it was found that the direct indexes,such as triggering rainfall intensity and inducing rainfall amount,were the key indexes for triggering debris flows. Different rainfall thresholds and models should be applied in different regions,according to the different effort of key rainfall indexes,due to the local underlying conditions,and especially climate conditions. The rainfall thresholds include peak rainfall intensity（ Imax）,triggering rainfall amount（ E）,the relationship between mean rainfall intensity and duration（ I- D）,rainfall intensity and rainfall amount（ I- R）,and so on.These models could be used in different regions individually and their thresholds vary accordingly. It was also found that the rainfall thresholds are rising during the past several years,but still need a long time to recover to the thresholds level before the earthquake. This study can help for the debris flow forecasting and mitigation in the Wenchuan Earthquake stricken area in the following years.