Study On Temporal And Spatial Variation Of Agricultural Meteorology Arid In Eastern Agricultural Areas Of Qinghai

The eastern agricultural areas of Qinghai plays a very important role on Qinghai's agriculture and the national economic development. However, drought is the seriously restricted factor of agricultural sustainable development in eastern agricultural areas.Therefore, it is an important strategy for the drought prediction and prevention to study temporal and spatial variation characteristics of agricultural drought climate and to analysis the major meteorological factors effecting spring drought and spring-summer drought. In this paper, according to the 1960～2005(46a) series datas of 18 meteorological stations in eastern agricultural areas compilated by weather bureau of Qinghai , the change law of reference crop evapotranspiration( ET 0),precipitation ( P ),aridity index( K ),quantity of water deficit(WSD )and the major meteorological factors effecting spring drought and spring-summer drought was analysised.(1)The annual mean value of reference crop evapotranspiration in eastern agricultural areas is 904 mm.The spatial distribution was that ET 0decreased from Southeast to Northwest, firstly increased and then decreased from Southwest to Northeast.The seasonal distribution of ET 0 was summer>spring>autumn> winter.In one year, The value of ET 0 in spring and summer accounted for 72% of whole year. The value of ET 0 in autumn and winter accounted for less proportion,less than 30%. ET 0 showed a significant decreasing trend with time.(2) The annual mean value of precipitation in eastern agricultural areas is 402 mm. The spatial distribution was that precipitation decreased from the Northwest to Southeast. The seasonal distribution of precipitation was uneven, which was summer >autumn>spring > winter. In one year, precipitation in summer and autumn accounted for 79% of whole year. Precipitation in winter and spring accounted for less proportion.(3) The annual mean value of aridity index in eastern agricultural areas is 2.4. The spatial distribution was that precipitation decreased from the Southwest to North east. That was South was dryer than North. The seasonal distribution of aridity index was winter> spring> autumn > summer.It was because of the lack of precipitation in winter.(4) The eastern agricultural areas were divided into four areas,which was semi-humid area prone to drought,semiarid area,semiarid area liable to drought,arid area. Quantity of Climatic water deficit in the four areas was showed that the spring was the most. Except spring wheat in Huang Zhong station of semi-humid area prone to drought had a spot of water earnings in April and August. Spring wheat in 3 stations of other aeras had water deficit at different degree.Therefor, it's necessary to supplement irrigation and Strengthen drought prevention to obtain abundant harvest.(5) Spring and spring-summer were the main seasons for seasonal drought in eastern agricultural areas.The precipitation was the main meteorological factor effecting spring drought and spring-summer drought.