Regional Drought Evolution Characteristics And Forecasting Model In Guizhou Province

In recently years, along with the global climate change, drought tend to be frequently, every year, the drought caused enormous economic loss, and serious threat to normal man’s various social economic activities. China is a country with water storage, drought has become main restrictive factor that threaten to the economic development and the agricultural production, there is an urgent need to research into the characteristics and regularity of drought. Guizhou province is located in the second step slope, which is in the east of Yunnan-Guizhou plateau. The terrain is higher in the west and lower in the east, lying tilt from central to north, east and south. In recently, drought occurs frequently in Guizhou. The degree aggravating and the influence area expanding constantly, and the contradiction between supply and demand of water resources become more prominent. Drought has become important factor that affect the economic and social development in Guizhou. Therefore, analyze and scientific forecast the characteristics and regularities of the drought in Guizhou karst regions is of great significance for disaster prevention and mitigation. This paper researched the drought occurrence and evolution regularities and the precipitation prediction method by using years of meteorological data in Guizhou karst regions. The main results were as following:(1) Analysis of drought characteristics in Guizhou karst regions. Based on precipitation and temperature observed data from1961to2011of WuJiang, YuanJiang, BeiPanJiang, HongShui River, ChiShui River, QiJiang and LiuLiang water system in Guizhou karst regions, using Palmer drought index, precipitation percentage and Z index, and introduced Malikov Criterion Additional Error Control Method, this paper analyzed the annual and quarter drought characteristics in Guizhou karst regions. The results show that Palmer index described the research region drought intensity more accurate, the method considers multiple factors such as precipitation, temperature, surface transpiration and runoff synthetically, it is suitable for drought characteristics analysis in Guizhou karst regions where Karst development, fast surface water catchment and poor soil water storage capacity.(2) Based on the Monte Carlo Algorithms and its distribution function, using P-III type distribution function to simulate the precipitation, and combining the Monte Carlo Algorithms and NNBR model, this paper proposed precipitation forecast model which is based on the combination of Monte Carlo Algorithms and NNBR model, and used backtracking algorithm to test the predict rainfall sequence. Results show that based on NNBR model combined with Monte Carlo Algorithms to predict rainfall is more accurate.(3) Using precipitation data in1961-2010of Wujiang Drainage Area to verify and compare three prediction model Markov, weighted Markov and trend weighted Markov, and the results show that the trend weighted Markov prediction effect is better than the other two models, it provides a new way for improving the rainfall forecasting precision.(4) Using BP neural network, Radial Basis Function(RBF) neural network and Elman neural network established drought forecasting model of the study area respectively, and compared and analyzed of the three kinds of prediction model, the results show that the Radial Basis Function(RBF) neural network has a better prediction effect.(5) With gray prediction model as the core, established wavelet decomposition- different frequency components with different model architecture, and introduced waveform prediction, and rainfall gray prediction optimization scheme is established. Practical application results show that the method is very good to solve large vibration frequency problems, and has high prediction accuracy, it implements the method innovation.(6) According to the measured temperature, precipitation and sunshine time data in1961-2010of19meteorological offices and stations in Guizhou province, and by using comprehensive drought index (CI), the drought frequency, coverage, last days of process and intensity in Guizhou province in recent50years are analyzed and calculated. Spatial analyses for drought years average number of different strength and different coverage area are realized by geographic information system software ArcGIS9.3, different grade drought, evolution process and the range and intensity of drought in the research area are reflected intuitively and visually, it provides scientific basis for disaster prevention and reduction.In conclusion, the main innovation points are as follows:(1) The first attempts to combine model based on the nearest neighbor sampling regression (NNBR) with Monte Carlo Algorithms to analyze the variation trend, cycle characteristics and mutation features of drought.(2) Using trend weighted Markov model in rainfall forecast, thus introduced a new method for accurately precipitation predictions.(3) Combined gray model with wavelet, took the precipitation data wavelet decomposition, forecast different frequencies components respectively, of which using gray model to the low frequency component forecast and waveform prediction method to high frequency component forecast, and put forward the gray forecasting model based on wavelet decomposition.