山西省降水量时空变化及预测

山西广布高山与岩溶,是华北平原地表水产流区和地下水补给区.研究该区域降水时空变化有利于全面认识华北平原干旱问题.应用时间序列聚类、突变点检验、趋势分析和小波-支持向量机模型揭示降水时空变化并预测.按降水变化特点划分北部高纬区、太行山高山区、北部高山高原区、中部盆地区、中西部高山高原区和南部盆地区等子区.太行山高山区和南部盆地区降水偏多,北部高纬区降水偏少.同纬度的盆地降水少于高原和高山.1965—1991 年,山西南部、东部、中部和北部降水量相继显著下降,1957—2012年平均下降速率为-1.5 mm/a.山西自20 世纪90 年代整体进入偏干阶段,直接导致地表产流和地下水补给减少,加剧华北平原干旱.预测结果表明,2013—2020 年山西降水平均变化速率约16 mm/a,有利于遏制干旱.

Tempo-spatial Variation and Forecast of Precipitation in Shanxi Province

Shanxi Province, where there are widely distributed mountains and karst systems, is the area of surface runoff yield and groundwater recharge for the North China Plain (NCP). Knowledge of tempo-spatial variations and forecast of precipitation in Shanxi could improve the understanding of droughts in the NCP. In this study, spatial distribution of precipitation was clarified based on time series clustering. Features of temporal variance of precipitation were revealed using breaking point test and trend analysis methods. A wavelet- support vector machine model was established to predict the precipitation in the future. As results showed, six sub-regions with different precipitation variation characteristics were identified, which are the North High-latitude Area, the Taihang Alpine Area, the North Mountains and Plateau Area, the Middle Basin Area, the Middle-West Mountains and Plateau Area, and the South Basin Area. More precipitation presented in the Taihang Alpine Area and the South Basin Area, while lessprecipitation occurred in the North High-latitude Area. Precipitation in basins was less than in mountains and plateau area on the same latitude. From 1965 to 1991, annual precipitation decreased significantly in the South, the East, the Middle and the North sequentially. The average rate during 1957 to 2012 is -1.5 mm/a. As a result, the area of Shanxi Province entered an arid period in whole since 1990s. Accordingly, runoff declined and groundwater recharge reduced. Decrease in precipitation of Shanxi in recent decades was evidently one of the driving factors of droughts in the NCP. The study region will get out of the less precipitation period before the year of 2020 with an average gradient of 16 mm/a, which would relieve droughts in the NCP.