Based on the data from 1998 to 2005,area rainfall,flow of main hydrologic stations in Duhe River and upstream water level of the dam of Huanglongtan Reservoir in the lower reaches of Duhe River were analyzed,and the standard of flood-producing rainstorm in Duhe River was given,while temporal and spatial distribution and circulation flow situation characteristic of flood-producing rainstorm in Duhe River were studied.The results showed that the flood-producing rainstorm in Duhe River was mainly continuous intensive precipitation with the characteristic of long duration.There was most rainfall in Zhuxiquan River,Zhushanguandu River and southwest part of the middle and upper reaches of Duhe River,and next came Zhuxi River.Flood-producing rainstorm occurred in Duhe River with some favorable circulation features.For example,it was more favorable in the west Pacific subtropical high,and the convergence zone at northeast-southwest direction was formed between subtropical high and continental high pressure at 700 hPa,while southwest vortex moved eastward.Low pressure system at 850 hPa in south part of plateau developed and moved eastward to Chongqing region and formed low vortex or shear near Duhe River basin.Moreover,the characteristics of physical quantity field were analyzed,the results showed that temperature in plateau area and the south area of Duhe River basin increased obviously before rainstorm,and east pathway was the main path of cold air which affected flood-producing rainstorm in Duhe River.There was a θse intensive belt with NEE-SWW direction at 30°-40° N at 925-500 hPa,and moisture convergence was beneficial to the occurrence of rainstorm in Duhe River.
