Preliminary study on drought zonation of winter wheat in North China Plain

Drought is characterized by short of precipitation and reduction of crop yield. ?Taking the negative precipitation anomaly and reduction percentage as indices,? the paper analyzed systematically the negative precipitation anomaly and reduction percentage occurred in different frequencies. The distribution and frequencies of drought in different degree were determined. It was shown that heavy drought was taken place once in 10 years and accounted for seventy-three per cent in area, concentrated in northeast of Henan and southwest of Shandong Province. While the mediate drought was taken place once in three to four years and accounted for ninety-three per cent in area. The light drought was once in two years and accounted for ninety-eight per cent in area. The zonation of drought disaster was made by use of the integrated index of drought disaster. The region with heavy drought disaster was the maximum in negative precipitation anomaly and the highest in yield reduction.