Analysis of Drought-Flood Characteristics in Zhanjiang

The characteristics of the monthly drought-flood identified with Z-index were analyzed in Zhanjiang.The results show that there is high frequency of very drought,utmost drought,very flood,utmost flood.The frequency of drought-flood is high during later phase of raining season(September and October) and later phase of drought season(February and March),is lower during middle phase of raining(June and July) and early phase of drought season(November and December).It is common that drought and flood occur in one year.There were more droughts in 1950s,1960s and from 2001 to 2005,there were more floods in 1970s,1980s and 1990s.It has been changed from more droughts to more floods since 1970s.The droughts and floods have periods of 7～8 months,10～11 months,and 13～14 months.