Applicability analysis of palmer drought index in Yunnan- Guizhou Plateau in China

Abstract

Monitoring and assessment of droughts is of primary importance for meteorologists, ecologists, freshwater managers and government decision makers. As a widely used drought monitoring index, the applicability of PDSI is very important. This study evaluates the applicability of PDSI over the Yunnan-Guizhou Plateau in China by utilizing time series and correlation analysis between ground observations and actual drought and flood records. The main conclusions were as follows: 1) the dry and wet conditions in the study area were divided into two periods. The climate was wet from 1951 to 2003, except for 1961, 1963-1964, 1988-1990, and the wetting level reached medium strength in 1966, 1968, 1983-1984, 1992, 1996, 1998 and 2000. Since 2003 to 2015, there had been a trend of drought, and the degree of drought is large, especially in 2006 and 2010-2014, some years reached severe drought. The spatial distribution characteristics of multi-year PDSI was not obvious in the plateau area. There had been a slight drought in south-central Yunnan province and south-eastern Guizhou province. 2) The water loss caused by surface runoff was serious in plateau area. There was a high positive correlation between PSDI and surface runoff at a 99% probability level, which further indicated that surface runoff was the main factor leading to drought in this region. 3) The assumptions of PDSI model is suggested to be modified in the region like Yunnan-Guizhou Plateau: when the upper soil’s water content reaches the lower soil’s water content, surface runoff occurs. It is expected to provide references for the applicability analysis of PDSI in different underlying surface/subsurface conditions.