关键词: 干旱指标, 平凉地区, 适应性

Abstract:

Based on the daily and monthly temperature，precipitation and evaporation data from 7 stations of Pingliang during 1965 －2010，the monthly drought indices of each station in recent 46 years were caculated with K index，PDSI，CI and Z index，respectively，and the application of four indices in drought variation，drought degree and range was analyzed and compared． The results show that K index，CI and Z index has close corresponding relationship with precipitation in most time，while PDSI was insensitive to precipitation variation． Each index could reflect the drought occurrence but with different intensity and extension． The intensity and extension reflected by K index was more serious than the other three indices in drought years or ordinary years，while that reflected by Z index was obviously smaller，and PDSI and CI was between K index and Z index． K index was closer to actual drought situation in serious drought years，but the adaptability of Z index was the worst． In ordinary years，PDSI，Z index and CI were more suitable，but the adaptability of CI was worst in winter． Drought is a complex cumulative process，so suitable drought indices should be selected considering moisture conditions in prophase and various factors which influence the occurrence and development of drought．

Key words: drought indices, Pingliang , adaptability, analysis