The Study Of Precipitation Trend In The Guanzhong Basin

Water resources are the source of life. The precipitation of the Guanzhong Basin whichAccounted for21.4%of the total water resources,48.6percent of the recharge accounts forGroundwater Resources is one of the main supply source of the Guanzhong Basingroundwater and terrestrial water. The extent of its wet or has a direct impact on local waterresources. Precipitation trend analysis and mutation testing is the main feature of theprecipitation changes. This article is mainly on the Guanzhong Basin precipitation in thesetwo areas to study.The Mann-Kendall method which is the internationally recommende does not requiresamples to comply with certain distribution without the interference of a few outliers, anddoes not require a statistical analysis, applies to the hydrological, meteorological and othernon-normally distributed data. The Mann-Kendall trend Act requires that the sample size tomore than40. This method can be very clear to give a reliable basis to judge, if fewersamples can also use this method gives a quantitative judgment is that we expect. Therefore,the Mann-Kendall trend method has been improved and applied to the Guanzhong Basin,precipitation trends.Mann-Kendall mutation test method for different problems, sometimes appearsinspection mutation points more, some of which is not the real mutation, but the noise.Therefore, this method improved and perfected, can effectively help to remove noise, andused in the Guanzhong Basin precipitation mutation test.In this paper, the precipitation statistics for the Guanzhong Basin,1959-2006, firstapplied to improve and perfect the Mann-Kendall method to study and analyze precipitationtrends of the Guanzhong Basin.Mature then combined with the past trend analysis andmutation test method comparative analysis of the Guanzhong Basin precipitation andseasonal variation of trends and mutation. At the same time, the selection of support vectorregression machine theory, short-term forecast of the annual precipitation of the GuanzhongBasin. The results show that precipitation has shown a decreasing trend in general, the downward trend in precipitation in spring and autumn, while the upward trend in summerand winter. and annual mutation occurred in1993, since the beginning of the year, totalprecipitation began to fall, to the21st century is still showing a decreasing trend; Mutationin spring occurred in1994, precipitation has a clear downward trend; Change point in springoccurred in1978, precipitation began to rise. Autumn precipitation mutated and declinedsince1973; The winter precipitation keeped an increasing trend，which change pointoccurred in1962and1999.