Abstract: Researching the temporal and spatial distribution characteristics of debris flow in mountainous area of southwest China under the influence of El Nino-La Nina event will be conducive to providing basic guidance for the prediction of debris flow disaster. According to statistical data, we examined the spatiotemporal coupling relationship between debris flow events and El Nino-La Nina events in mountainous area of southwest China through GIS spatial analysis approach. We found that 1) in El Nino-La Nina year, the frequency of debris flow disaster in mountainous area of southwest China increased in temporal scale, and the occurrence frequency in La Nina year was larger than that in El Nino year; 2) in spatial scale, under El Nino and La Nina events, debris flow disaster was mainly concentrated in mountainous area of southeast Tibet, Hengduan Mountains, northeast Yunnan Province, west and southwest parts of Guizhou Province, northwest Yunnan Province, Dadu River basin, and Yalong River basin, etc; 3) in El Nino-La Nina year, rainfall amount in the debris flow stricken area was larger than multi-year average rainfall in general. We conclude that debris flow events in mountainous area of southwest China are evidently correlated with El Nino-La Nina events.

Key words: debris flow disaster, El Nino, La Nina, GIS spatial analysis, mountainous area in southwest China