The Analysis On Approximate Cycle Of Natural Yearly Runoff And Low Water Period In Yellow River Sanmenxia Station

This dissertation makes a systematic detailed study on the natural yearly runoff approximate cycle and low water period on the Yellow River baisn by means of the theory of hydrology and statistics on the base of the predecessors' studies. Thoroygh the research on the natural yearly runoff approximate cycle on the Yellow River baisn, the approximate cycle and the recurrence intervals on the Yellow River baisn have been distilled.Approximate cycle of Sanmenxia natural yearly runoff in Yellow River is identified, denoted and distilled used the method of self-correlation and frequency analysis. Natural yearly runoff includes 3 series, from 1470 to 2002, from 1919 to 2002 and from 1949 to 2002. In order to demonstrate the rationality of 11 years period of long series natural yearly runoff, the period of sunspot from 1756 to 2000 is analyzed.In addition, through plotting the hydrograph of mean annual and natural yearly runoff and the residual mass diagram of frequency factor from 1919 to 2002 in Sanmenxia Station, 2 continuous low water periods from 1922 to 1932 and from 1990 to 2002 are obtained. And the 2 recurrence intervals in long term series from 1470 to 2002 are analyzed. From 1470 to 2002, the low water period from 1922 to 1932 appeared 7 times, the recurrence intervals is about 70-80 years; the low water period from 1990 to 2002 appeared 4 times, the recurrence intervals is about 130~l 40 years.