Analysis On Characteristics Of Annual Precipitation And Meteorological Drought In The Irrigation Distract Of Longtouqiao

In recent years,with the growth of population and economy,deterioration of global environment and water shortage become more and more serious,The problem of drought is closely related to human survival became more and more prominent,research on drought problem has aroused widespread understanding,scholars become urgent need to solve this problem.Longtouqiao irrigation is in Sanjiang plain hinterland,it belongs cold temperate continental monsoon climate zone,it is hot and rainy in summer,the winter of Longtouqiao irrigation is cold and long.Drought occurred frequently in spring,not only seriously destroyed the ecological environment of the region,but also directly affected the agricultural development in the region,and indirectly hindered the economic development rapidly,Therefore,the in-depth study of Longtouqiao irrigation drought situation,it is not only necessary for the drought resistance job in Longtouqiao irrigation,but also provide an important basis for realizing the high-efficient comprehensive utilization of multiple water sources in the irrigation area and promoting the coordinated development of water resources in irrigation system.Firstly,the moving average,the accumulated variance analysis methods,the M-K(Mann-Kendall)mutation test and the Morlet wavelet analysis were used to study the change characteristics of precipitation in the past 55 years in the Longtouqiao irrigation,and the weighted Markov chain model was used to predict the annual precipitation of the Longtouqiao irrigation.Then,the application of round analysis method,Run-length analysis method,discussed the transfer probabilities of runoff and the distribution characteristics of continuous runoff years,used the drought intensity and the transfer probabilities of runoff described the meteorological drought characteristics of the Longtouqiao irrigation.Finally,the GM(1,1)model was used to forecast the grade of the meteorological drought of the Longtouqiao irrigation.The following are the research contents and conclusions:(1)Analysis of characteristics of precipitation changeAs for the annual variation,the precipitation of the Longtouqiao irrigation showed a downward trend,the precipitation is uneven distribution during the year.There had been mutations in Longtouqiao irrigation in 1961.The cumulative precipitation curve of the Longtouqiao irrigation showed a trend of rising and then decreasing.The precipitation of theLongtouqiao irrigation in 0-10 a time scale shock evidently in 1960-1983.There are 2 statistical major cycles in the annual precipitation anomaly of the Longtouqiao irrigation at the level of95% confidence level,for the period of 3 years and 11 years.(2)The establishment of prediction model of precipitationBased on the annual precipitation sequence in 1959-2012 of the Longtouqiao irrigation established weighted Markov chain model forecasting the precipitation,and used the actual data of the precipitation of 2013 to validate the validity of the model,the results show that the precipitation forecasting model constructed is effective.Finally,using the model to predict the annual precipitation in 2014,the state of runoff is a normal precipitation year.(3)Analysis of meteorological drought characteristicsThe frequency of occurrence of continuous dry years are large than continuous wet years in Longtouqiao irrigation in 1959-2013,the number of the average continuous dry years are greater than the number of the average continuous wet years;The smooth transition probability of partial dry and partial wet is more large,it is favorable for using the water;The frequency of occurrence of partial dry years is the highest,then is the partial wet years,the last is the dry years;the 2-7a continuous dry years of the Longtouqiao irrigation not only has higher frequency of occurrence,but also has larger drought intensity.(4)The establishment of prediction model of meteorological droughtBased on the annual precipitation sequence in 1959-2013 of the Longtouqiao irrigation established the GM(1,1)prediction model and rating the prediction accuracy,the result accord with the forecast precision requirement,then used the GM(1,1)model predict the drought year.(5)The causes of drought and drought mitigation measuresThis paper analyzes the causes of the drought of the Longtouqiao irrigation,and puts forward solving the measures of the irrigation water shortage.