摘要:
用变差系数作为衡量其变化幅度大小的指标,运用二元定序变量的Spearman相关分析方法,对贵州省2000年退耕还林以来的河流输沙量、输沙模数和泥沙含量的时空变化与降水量的关系进行了分析.结果表明:贵州省退耕还林以来,河流的输沙量、输沙模数与含沙量均呈减少的趋势,三者的年际变化幅度比较小,但是比其降水量的变化幅度大;从空间差异看,贵州长江流域多年的平均输沙量、输沙模数和河流含沙量比贵州珠江流域的大,而河流输沙量、输沙模数与含沙量的年际变化幅度则比贵州珠江流域的小;贵州的输沙量与降水量的Spearman相关系数为0.897,关系密切,其回归统计方程模型为y=x1.223.
Abstract:
Since its initiation,the environmental effect of the project invested by the Chinese government,which is a major forestry ecological project for returning farmland to forest in Guizhou Province,has attrac ted much attention.This study attempts to clarify the temporal and spatial variation characteristics of soil erosion and their influence on distribution of precipitation on the ground,which can reflect the effect of this project and help further controlling of soil erosion.We analyze the spatial and temporal changes of amount of sediment transport,modulus of sediment transport,sediment concentration and their relationship with precipitation in Guizhou since 2000.The coefficient of variations is used as the index to measure the magnitude of the change and the Spearman correlation method is employed for analysis.Results show that the amount of sediment transport,modulus of sediment transport,and sediment concentration have a tendency to reduce since the project initiation,of which all the inter annual amplitudes are small,but greater than that of precipitation change.From spatial differences,the average amount of sediment transport,modulus of sediment transport,and sediment concentration in the Yangtze River basin of Guizhou are larger than those in the Pearl River basin of Guizhou,whereas the inter-annual variations of these parameters are smaller than those in the Pearl River basin of Guizhou.The correlation of precipitation and amount of sediment transport is 0.897,indicating a close relationship.The regression equation model is y=x1223,which shows that the environmental effects of the project are insufficient and further efforts in construction are required.
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