Analysis of Persistence of Hydrological Drought on the Upper Yellow River

Utilizing four kinds of hydrological data from observed,investigated,historical and synthetic series,a comprehensive analysis of drought persistence is made in this article.The results confirm that the persistence of hydrological drought on the upper Yellow River exists,that the 11-year drought from 1922 to 1932 did occur on the upper Yellow River,and that the results of field investigations are reliable.The frequency analysis for yearly runoff of various lengths of persistense has been made with synthetic series.Owing to the extreme severity of the 1922-1932 drought persistence,its recurrence period is far larger than that estimated before.The design of operation of the Longyanaxia Reservoir and Hydropower Project would be more beneficial if the results of this paper were used.