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 o...