Study On Uniformity And Intensity Of Precipitation Change In Hexi From1960to2009

The global warming has become hotspot topic within scientific community andalso the great concern for our societal development. It has been confirmed that globalwarming by referring to data of ground temperature, sea-level altitude, and snowcover area, etc. And it also pointed out the global warming had impacted on theredistribution of precipitation. In Northwest area, secluded hinterland of Eurasiaterrain, moisture sources that leads to poor stability of precipitation is subjected toconsiderable limitations. Hexi area is an important commodity grain production base,and water conditions is the most important material foundation for the development ofagriculture and the limiting factor, to some extent will affect the planting structure andtypes of farming. Therefore, this paper aims to analyze the characteristics of the Hexiprecipitation uniformity and different levels of change in the past50years, in order todeepen the understanding of the Hexi area of climate change, and thus provide thebasis for the scientific guidance of local agricultural production activities.The analysis was based on the meteorological datasets from1960-2006in13stations in Hexi. The Gini coefficient of precipitation is calculated, and the theprecipitation level is divided reasonably. As a result, This article draws the followingconclusions:(1)The annual precipitation in the area shows obvious change, but the spatial andtemporal distribution of the difference is quite significant. From the time scale, theannual precipitation in the Hexi region was low in the1990s, and entering into the21st century, precipitation increased significantly. Judging from the spatial scale, thechanges in precipitation was outstanding performance in the central and eastern areas.Zhangye as the boundary, the precipitation in west of the region is less comparingwith the east regions, and the most precipitation was mainly in the vicinity ofWushaoling.(2) The uniformity of precipitation is also changing. after1970s, the Ginicoefficient in Jiuquan and Dingxin reached0.75, the21st century later, the entireprecipitation Gini coefficient shows increasing trend. In addition, the unevendistribution of precipitation in the region was shifted. During1960s、1970s、1980s、precipitation uneven areas were mainly concentrated in the western region and into the1990s, uneven regional precipitation gradually shifted to the central and easternareas, including the eastern part of the more significant areas. From the long-termtrend, the precipitation uniformity will still fluctuate in time and space.(3) From the inter-annual variation, different levels of precipitation daysexperienced an increasing trend; light rain, moderate rain precipitation intensity alsoshowed an increasing trend, the rain precipitation intensity was obvious decreasingtrend; light rain, moderate rain precipitation contribution rate showed a slightdecreasing trend, heavy rain was weak increasing trend. From the spatial variation ofview, different levels of precipitation days Zhangye City line as the boundary, the areato the east less precipitation days, but the intensity of precipitation, on the contrary,the area west of precipitation days, precipitation intensity; rain precipitationcontribution rate, located in the western region, moderate rain, heavy rain,precipitation less contribution rate, mainly in the central and eastern areas(4) Using of R/S, according to the annual precipitation, day number ofprecipitation, precipitation intensity, precipitation contribution rate, the results werepredicted, it showed that the annual precipitation in the region experienced anincreasing trend. Light rain and moderate rain days was also found an increasing trend,heavy rain days showed a significant decreasing trend; drizzle and moderate rainintensity was not significant increasing trend, while the contribution rate was notsignificantly reduced.(5) Hexi area precipitation change is mainly caused by the rain days andprecipitation intensity, precipitation days effect is more significant, Hexi areaprecipitation increases obviously in the east. From the point of the whole area, altitudeand precipitation change were significantly positive correlation.