A DROUGHT PREDICTION MODEL IN NORTH CHINA PLAIN AND ITS APPLICATION

A drought prediction model in North China is developed based on the response curve of phototsynthesis rate of winter wheat to water stress and the concept of agricultural drought stress index and of agricultural drought early warning index. The results of simulated agricultural drought for 432 dekads in 1998—2000 for Beijing, Shijiazhuang, Zhengzhou and Jinan show that the accuracy of agricultural drought trend prediction is 90.7% and the accuracy of agricultural drought quantitative prediction is 87.5%. In addition, the model is able to predict drought in a region. The model is applied to a numerical analysis for agricultural drought in 1961—2000 in Beijing. The results show that agricultural drought occurs nearly every year under normal climatic condition in Beijing, especially the severe drought occurs in the period from grain filling to maturity of winter wheat. But the severe level of drought stress in each year is different, there is a 3—6 cycle according to the power spectrum analysis. According to the temporal and spatial analysis for agricultural drought in North China under normal climatic condition, it is found that the agricultural drought stress indexes strengthen gradually from flowering, grain filling to maturity of winter wheat in North China. It conforms to the fact of agricultural production in North China.