Temporal And Spatial Evolution Characteristics Analysis Of Qinghai Lake Basin Precipitation

Precipitation is the main source of the Qinghai Lake or river andgroundwater recharge. The meteorological station and hydrologicalstation are sparse, and the majority of stations have short precipitationtime series in Qinghai Lake basin. So, it’s very important to do spatialinterpolation with the discrete data and GIS software. We can get thespatial distribution of precipitation results in whole research area andprovide necessary help to life, production and scientific research. In thisarticle, monthly precipitation data of18meteorological stations andhydrological stations in Qinghai Lake basin and surrounding areas wereused to analyze the spatial and temporal trend of precipitation from1961to2010. The results showed that:(1) This paper uses four kinds of spatial interpolation method forinterpolation of contrast. In the four methods, both the SIMPLEKRIGING and COKRIGING methods can reflect the spatial distributionof precipitation in the Qinghai Lake basin. These two kinds ofinterpolation method’s interpolation accuracy have no substantial difference. In general, COKRIGING has higher precision and betterdrawing effect than other methods. This method apply to precipitationspatial interpolation of the Qinghai Lake basin.(2) According to the interpolation result analysis of the different timescales, year scale interpolation accuracy is higher than that of monthlyscale interpolation accuracy. It means that precipitation spatialdistribution increase variation and interpolation error, as the smallerspatial scale.(3) Look from the spatial distribution, the whole research area hasuneven distribution. The site average precipitation of Qinghai Lake basinis lower in the west and higher in the east. The average annualprecipitation gradually increased from193mm of the western basin to535mm of the eastern basin. Qinghai Lake basin’s precipitation hasgreatly annual changes. The variation coefficient of annual precipitationis between0.1and0.3. Look from the distribution of precipitationtendency rate, precipitation tendency rate of Qinghai Lake basin hasincreased to some extent. The precipitation tendency rate is7.33mm per10years and the west area increased more significantly than the eastarea.(4) The seasonal distribution of precipitation is uneven. The summerprecipitation accounted for the largest proportion of the annualprecipitation. Summer rainfall can be accounted for53%to69%of thewhole year. And the fall precipitation can be accounted for13%to22% of the year. Look from the distribution of precipitation tendency rate,summer precipitation tendency rate of Qinghai Lake basin has increasedto some extent. The summer precipitation tendency rate is7.2mm per10years and the west area increased more significantly than the east area.(5) The monthly distribution of precipitation is uneven. In July andAugust, it has the greatest rainfall. Monthly rainfall can account forabout20%to25%for the annual rainfall. The four maximum monthlyprecipitation of Qinghai Lake basin mainly concentrated in the flood andaccount for75%to80%of the annual precipitation.