Analysis on the Annual Natural Runoff Variety Process of the Yellow River

Natural runoff variety and current forecasting researches are very useful for terrestrial water cycling and water balance research and water resources management. Based on the 79-year-annual -runoff data from 1919 to 1997 of Shanxian hydrological station, the annual natural runoff variety process of the Yellow River was analyzed and the runoff in the future was forecasted furthermore. The stages of the natural annual runoff variety process are clear when a method with accumulated deviation from average runoff as its parameter was used. With harmonic analysis, it was shown evidently that the variety process has several periods, such as 39a, 26a, 4a, and 3a. From the current of variety process , the runoff was in low water period presently and natural annual runoff would be up to the average in 2010, that was to say the low water state presently may be last about 10 years.