Meteorological Drought Analysis And Prediction In The Irrigation District Of Baoji Gorge

In recent years, the world environment is deeply deteriorated and the shortage of water resource is more serious along with the development of economy and the increase of population, drought problem that concerned with the human life becomes more serious than ever before, people begin to concern it. The study of drought problem becomes the main subject to more and more academician. The irrigation district of Baoji Gorge is located in west of Shanxi province. The dry climate causes drought to occur more frequently. Ecological environment is destroyed and agriculture development is hampered by drought. All of those influence the development of economy. Characterization of droughts in the irrigation district of Baoji Gorge will be useful not only for the development of drought preparedness plan in the irrigation district of Baoji Gorge but also for the provisions of the integrated water resources management in the Wei River basin.In this paper, the Mann-Kendall statistic test method is used to estimate the temporal characteristics and variations for the long-term trend of precipitation in the irrigation district of Baoji Gorge from 1981 to 2004. The run method, displacement theory and stochastic process theory are used to analyze the continuous high water and low water, the transfer probability and its distribution features. Based on the index of drought intensity, drought period and transfer probability between high water and low water, the meteorological-drought characteristics is investigated in the study area. The main conclusions and contributions of the dissertation include:1) The probability of continuous low flow years was larger than that of continuous high flow years. The periods of continuous low flow years were longer than that of continuous high flow years. The jump change from a low flow year (high flow year) to partial high flow year (partial low flow year) had negative effects for irrigation. The probability of partial low flow year was the greatest, and then partial high flow year, the probability of low flow year was the smallest. The frequencies of the 2 or 3 low flow years were high and the intensities were great from 1981 to 2004.2) The low flow was the main characteristics of the irrigation district of Baoji Gorge, which had negative effect for the use of surface water and was disadvantage for drought relief. The occurrence frequency of low flow year was more than 54%, which is very important to the prevention of both flood and drought. The frequency of partial low flow year gave the greatest value at 47.2%, which means that this kind of low flow reappeared in less than three years and it is the major meteorological drought in the irrigation district of Baoji Gorge. The frequency of moderate flow year and low flow years was about 70%, which should be paid more attention in the water resources management.Drought forecast is very important. By forecasting the dynamic procedure of drought, which includes occurrence, evolution decline and fading away, some measures are taken that could reduce the loss caused by drought in many ways. The thesis introduces the method of forecast in climate and agriculture and the details of the weighted Markov Chain model and the Grey disaster forecasting theory, which are used to predict the drought in the irrigation district of Baoji Gorge. The weighted Markov Chain model,the grey disaster forecasting theory are used to predict the drought in the irrigation district of Baoji Gorge. Through model calibration and validation, the GM (1, 1) model performed well with high precision, which proved that the grey system theory may be used to forecast the drought in the irrigation district of Baoji Gorge.The thesis introduces the details of Time Series Analysis (TSA). Using ARIMA model to analyze the yearly average rainfall from 1981 to 2001 in he irrigation district of Baoji Gorge, the result shows that the ARIMA (2, 1, 3) and ARMA(1,2) models can supply the relative precision, both the models can be used to forecast the precipitation.The purpose of disaster forecasting is to relieve and prevent drought better. On the base of drought evaluation in he irrigation district of Baoji Gorge, strategy of drought resistance is put forward. This paper analyzes the reasons of drought in the irrigation district of Baoji Gorge, evaluates the affections and loss caused by drought disasters to different business, social-economy, and environment, and this paper deals with countermeasures to solve the problems of anti-drought and water shortage: develop technology of irrigation, reinforce drought disaster forecast and control, utilize water resources reasonably.