Abstract:

Based on the monthly precipitation data from 61 national weather stations during 1961-2017 in Liaoning province, the characteristics of spatio-temporal variation of abrupt alternation of drought and flood during precipitation concentration period were analyzed using the linear tendency, trend analysis, stage analysis, sliding t-test curve, and ArcGIS spatial interpolation methods, in which the stage from May to August was selected as the research time to establish a sequence of drought-flood abrupt alternation index (DFAI).The results show that the DFAI of precipitation in Liaoning province during the precipitation period from 1961 to 2017 decreases at a rate of -0.7 per decade, with thirteen years appearing drought-to-flood, and nineteen years appearing flood-to-drought.The intensity of DFAI shows a slight upward trend at a rate of 0.1 per decade.In recent 57 years, the drought-to-flood mostly occurs in 1960s, and flood-to-drought mostly occurs in 1970s and after 2000s.The first abrupt point appears in 1989.After 1989, the intensity of DFAI shows an increasing trend.Another abrupt point appears in 1994, with a decreasing trend.In a typical drought-to-flood year (2013), the high-value area of DFAI is distributed in the central and western regions.In the typical flood-to-drought year (2014), the high-value areas of the absolute value of DFAI are distributed in the northeast and central and western regions.The spatial distribution of the rate of change in DFAI shows an obvious difference, i.e., increasing in the middle and north, and decreasing in the east and west.

Key words: Precipitation concentration period, Drought-flood abrupt alternation index, Mutation