Preliminary Study on the Evolution of Historical Flood/Drought Features for the Northeast of China

摘要

Floods and droughts have been crucial factors for crop yields. Northeast China is one of the staple food-crop bases in this country. During the crop growth intensities of floods and droughts exert innegligible impacts on the growth and hence yield, This paper deals with these disasters based mainly upon data from representative stations over the region, which are treated by the "Binary Time Series" scheme^ (KecLem, 1980, one sequence for floods and the other for droughts) to investigate their regularity, persistence, turning point and periodicity. Therefrom we try to find some useful results. Customarily, past studies examined floods and droughts by use of a united time series. But, in fact, changes in the disasters are highly complicated and the previous methods leave much to be desired Hence, a "separate two variables filtering" scheme is employed for 40-year floods and droughts in the study region, together with relations of solar activities to the disasters addressed.