关键词: 汾河流域, 降水量, 地统计, Mann-Kendall检验, 时空变化

Abstract: The Fenhe River Basin is located in a semiarid and semi-humid region.As the main replenishment source,precipitation could exert the significant impact on the ecological environment and socioeconomic development in this basin.A dataset of monthly precipitation series (from 1971 to 2011) from 154 precipitation stations was used to analyze the spatiotemporal distribution of annual precipitation,precipitation in spring (from March to May),summer (from June to August),autumn (from September to November) and winter (from December to next January) as well as flood season (from June to September) in the whole Fenhe River Basin (FHRB) and its upper reaches (TUR),middle reaches(TMR) and lower reaches (TLR) during the period of 1971-2011.The geostatistical analyst module of GIS was used to compare and select the optimal interpolation model,and the nonparametric Mann-Kendall (MK) statistical method was used to test the trend and abrupt change.The study results are as follow: ① There were the similar spatial distribution patterns of annual precipitation and rainfall in summer and flood season in FHRB,TMR and TLR,the precipitation was in a decrease trend from the south to the north and from the mountainous areas to the basins,and the lowest rainfall value occurred in the central Taiyuan Basin.In spring and winter,the trend of isohyets was from the east to the west with a decrease trend from the south to the north.In autumn,the trend of isohyets was from the northwest to the southeast with a decrease trend from the southwest to the northeast.Spatial distribution of precipitation was homogeneous in spring and winter in TUR,while annual precipitation and rainfall in summer,autumn and flood season was high in the western mountainous areas than that in the eastern mountainous areas and central valley areas; ② As a whole,there was a negative trend of annual precipitation and rainfall in summer and flood season,but a positive trend of precipitation in spring,autumn (including TUR) and winter in FHRB,TMR and TLR.On the contrary,there was a positive trend of annual precipitation and rainfall in summer and flood season,but a negative trend of precipitation in winter in TUR.The liner trends of annual precipitation,precipitation in spring,summer,autumn,winter and flood season in FHRB during the period from 1971 to 2011 were -6.0 mm·(10a)^-1,5.3 mm·(10a)^-1,-10.0 mm·(10a)^-1,6.6 mm·(10a)^-1,0.2 mm·(10a)^-1 and -7.2 mm·(10a)^-1 respectively.All the decrease or increase trends were not significant (P>0.10); ③ Abrupt changes of annual precipitation and rainfall in summer,autumn and flood season were detected during mid-late 1970s,most of which occurred in 1979.After the abrupt years,precipitation trends were mainly negative but not reached the significant level (P>0.05).In spring,abrupt changes of precipitation were detected in 1973,and the positive trend reached a significant level (P< 0.01) in the 1980s.In winter,abrupt changes of precipitation were detected in 1973 in FHRB and TLR but in 1979 in TUR and TMR,and the negative trend reached a significant level (P<0.05) in 1999.

Key words: Fenhe River Basin, precipitation, geostatistics, Mann-Kendall (MK) test, spatiotemporal variation