The purpose of this study is to construct the objective historical record of drought events in Korea and to investigate the periodicity of it. The Effective Drought Index (EDI; Byun and Wilhite 1999) is applied to define the drought. The analyses are performed in 5 stations (here after ST1); the other is 1974-2005 in 57 stations (here after ST2). The periodicity of drought is evaluated by the wavelet and spectral analysis.

By using the precipitation data of Seoul that is holding a remarkably long term, the historical drought events have been summarized, of them the longest drought period finds out for 25 months between 1900y and 1902y. The droughts are gradually intensified and frequent in the 20th century even though the precipitation is increased in the 20th century.

Seasonal drought in Korea has been investigated by using ST1. As the results, 1) most droughts and severe droughts are shown in summer because precipitation is mainly concentrated in summer. 2) The drought periodicity is extended to 8-year periodicity in comparison with 4-year periodicity in the 1970's and its fluctuation is bigger than past. These characteristics are detected through ST2 by three periods. One is 1777-2005 in Seoul station; another is 1942-2005.