Research On Characteristics Analysis Of Drought And Precipitation Forecast In Qiqihar

Meteorological drought occurs frequently in Qiqihar City. Insufficient precipitation is the main cause for the local economic development and harmonious society construction. A better understanding of the occurrence and development of drought and the selection of objective drought prediction method in Qiqihar is, therefore, vital and undeniable to clarify the causes of the drought and the development of drought policy for the local government.This paper analyzed the evolution law of precipitation and characteristics of drought in Qiqihar based on the annual precipitation information during 1961 to 2013 from four meteorological stations in Qiqihar. In addition, an accurate and feasible prediction method for the drought was proposed in Qiqihar. The detailed research information is listed as follows:(1) The tendency of annual precipitation of the four observatories in Qiqihar is analyzed via five-point sliding average method, residual mass curve of coefficient of modulus, rainfall tendency rate analysis and M-K significance test. The results implied that the annual precipitation in Qiqihar is uneven distributed in the year and has significant annual variations; dry season alternates with wet period for every ten years and dry season is slightly longer than the wet period; and the annual rainfall of the four stations showed a slowly upward trend.(2) The characteristics and evolution trend of extreme precipitation in the four seasons of Qigihar were analyzed by three aspects of the limit precipitation, the duration of precipitation limit and the intensity of extreme precipitation using the average value of the precipitation data of four stations.The result shows that distribution of extreme precipitation in Qigihar is uneven in the season, there is not a significant reduction in the duration of the extreme precipitation of a precipitation,and the precipitation tends to be uneven. On the precipitation intensity, the extreme precipitation intensity of spring, summer and winter three seasons in Qigihar has an upward trend, but not obvious. Extreme climate has been enhanced, but the trend is slow, the precipitation intensity of extreme precipitation in autumn had a decreasing trend, but not obvious, the extreme precipitation climate has a tendency to be stable.(3) The drought characteristics of Qiqihar were analyzed by the precipitation anomaly percentage, Z index and humidity index. Overall, droughts occurred frequently in Qiqihar from 1961 to 2013. All the four observatories showed that droughts occurred in 1976,2000 and 2004 and the climate were relatively dry in 1968,1979,1995,2007 and 2008. In addition, drought occurred more frequently especially in spring and summer.(4) On the basis of Monte Carlo (MC) and BPEMD prediction model, this paper forecasted the droughts in Qiqihar and compared the prediction results of applying these two methods. The results show that it is inaccurate to forecast the extreme amount of rainfall in Qiqihar by MC, while the results that applying BPEMD prediction model are more accurate and suitable for the drought forecast of Qiqihar, for EMD empirical mode decomposition method can reduce the volatility of the original time series effectively.